PPT 112
2009 – 2010

Chapter 1 Pharmaceutical solutions
•
A solution is a homogenous one-phase system consisting of two or more components. o
The solvent is that phase in which the dispersion occurs and the solute is that component which is dispersed as small molecules or ions in the solvent.
In general, the solvent is present in the greater amount but there are several exceptions. For example, syrup BP contains 66.7% w/w of sucrose as the solute in
33.3% w/w of water as the solvent.
•
1Easier to swallow than solid dosage forms and are therefore particularly acceptable for pediatric and geriatric use.
2A drug in solution is immediately available for absorption. Thus, the therapeutic response is faster than that from a solid dosage form which will require a dissolution step before drug absorption takes place.
3A solution is a homogenous system with a uniform distribution of the drug throughout the preparation. In suspension or emulsion formulations uneven dosage can occur due to phase separation on storage and shaking is needed before use.
4Immediately diluted by the gastric contents which reduce irritation to the gastric mucosa caused by high local concentration of some drugs (aspirin, KCl) if administered as a solid dosage form.
•
1Liquids are bulky and are therefore inconvenient to transport and store. Moreover, immediate lose of the whole product occurs in case of breakage of the container.
2Poor stability of the ingredients in aqueous environment of solutions compared to that formulated as a tablet or capsule, which is particularly important for drugs susceptible to hydrolysis.
3Solutions often provide suitable media for the growth of microorganisms and may therefore require the incorporation of a preservative.
4Accurate dosage will depend on the ability of the patients to use a 5 ml spoon or, more rarely, a volumetric dropper. Inaccurate dosing may lead to loss of the therapeutic efficiency.
5The unpleasant taste of drugs is more pronounced in solutions than when in a solid form. Sweetening agents & flavors can be used to make solutions more palatable.

Chapter 1 Pharmaceutical solutions
•
o
Microbes will grow in an aqueous solution. Therefore, it is necessary that formulator should add a preservative to the product to decrease the probability of product contamination. o
The major criteria that should be considered in selecting a preservative are as follows:
1Effective against a wide spectrum of microorganisms.
2Stable for the shelf life of the formulation.
3Nontoxic.
4Nonsensitizing.
5Relatively free of taste and odour. o
Preservatives may be grouped into a number of classes depending upon their molecular structure, including:.
1) Alcohols
ƒ
Ethanol
is useful as a preservative when it is used as a solvent; however, it dose need a relatively high concentration, somewhat greater than 10% to be effective.
ƒ
Propylene glycol
is also used as a solvent in oral solutions and topical preparations, and it can function as a preservative in the range of 15 to 30%. It is not volatile like ethanol.
ƒ
Chlorobutanol and phenylethyl alcohol
are used in lower concentrations of about 1% for preservative action.
2) Acids
ƒ Benzoic acid has a low solubility in water, about 0.34% at 25°C. The concentration range used for inhibitory action varies from 0.1 to 0.5%. Only the nonionized form is effective, and therefore its use is restricted to preparations with a pH below 4.5.
ƒ
Sorbic acid
has also a low solubility in water, 0.3% at 30°C. Suitable concentrations for preservative action are in the range of 0.05 to 2%. Its preservative action is due to the nonionized form; consequently, it is only effective in acid media. Because of the double bonds in its structure, it is subject to oxidation.
3) Esters
ƒ Parabens are esters of p-hydroxybenzoic acid and include the methyl, ethyl, propyl and butyl derivatives. The solubility in water decreases as the molecular weight

Chapter 1 Pharmaceutical solutions increases from 0.25% for methyl ester to 0.02% for the butyl ester. These compounds are used widely in pharmaceutical products and are effective and stable over a pH range of 4 to 8. They are employed at concentrations up to a bout 0.2%. Frequently, two eaters are used in combination in the same preparation. This achieves a higher total concentration, and the mixture tends to be active against a wider range of microorganisms. Their activity is reduced in the presence of nonionic surface active agents due to binding. In alkaline solutions, ionization takes place and this reduces their activity; in addition, hydrolytic decomposition of the ester group occurs with a loss of activity.
The most widely used preservatives are mixture of Methyl parahydroxybezoate in a
0.2% concentration and Propyl parahydroxybenzoate in a 0.02% concentration. They are suitable for both external and internal use.
4) Quaternary Ammonium compounds
ƒ Benzalkonium chloride is used at relatively low concentration, 0.002 to 0.02%, depending on the nature of the pharmaceutical product. This class of compounds has an optimal activity over the pH range of 4 to 10 and is quite stable at room temperature. Because of the cationic nature of this type of preservative, it is incompatible with many anionic compounds such as surfactants and can bind to nonionic surfactants. It is used generally in preparations for external use or those solutions that come in contact with mucous membranes.
•
o
Methods of preparation fall into three main categories:
1 S i i m p l l e s s o l l u t t i i o n s s
ƒ Solutions of this type are prepared by dissolving the solute in most of the solvent, mixing until dissolved, then adding sufficient solvent to bring the solution up to the proper volume. The solvent may contain other ingredients that stabilize or solubilize the active ingredient.
ƒ Calcium hydroxide topical solution USP (lime water), sodium phosphates oral solution USP, and strong iodine solution USP are examples. Calcium hydroxide topical solution USP contains, in each 100 ml, not less than 140 mg of Ca(OH)
2
. The solution is prepared by agitating vigorously 3 g of calcium hydroxide with 1000 ml of

Chapter 1 Pharmaceutical solutions cool, purified water. Excess calcium hydroxide is allowed to settle out and the clear, supernatant liquid dispensed.
ƒ An increase in solvent temperature usually implies and increases in solute solubility.
This rule does not apply, however, to the solubility of calcium hydroxide in water, which decreases with increasing temperature. The official solution is prepared at
25°C.
ƒ Solutions containing hydroxides react with the carbon dioxide in the atmosphere.
OH
-
+ CO
2
→ HCO
3
-
OH
-
+ HCO
3
-
→ CO
3
2 + H
2
O
Calcium hydroxide topical solution, therefore, should be preserved in well-filled, tight containers, at a temperature not exceeding 25°C.
ƒ Strong iodine solution USP contains, in each 100 ml, 4.5 to 5.5 g of iodine, and 9.5 to
10.5 of potassium iodide. It is prepared by dissolving 50 g iodine in 100 ml of purified water containing 100 g of potassium iodide. Sufficient purified water is then added to make 1000 ml of solution. One g of iodine dissolves in 2950 ml of water.
However, solutions of iodides dissolve large quantities of iodine. Strong iodine solution is, therefore, a solution of polyiodides in excess iodide.
I
-
+ nI
2
→ I
-
(2n +1)
Doubly charged anions may be found also.
2I
-
+ nI
2
→ I 2-
(2n+2)
Strong iodine solution is used in the treatment of iodide deficiency disorders such as endemic goiter.
ƒ Several antibiotics (e.g., cloxacillin sodium, nafcillin sodium, and vancomycin), because they are relatively unstable in aqueous solution, are prepared by manufacturers as dry powders or granules in combination with suitable buffers, colors diluents, dispersants, flavors and/or preservatives. These preparations, cloxacillin sodium for oral solution, nafcillin for oral solution and vancomycin hydrochloride for oral solution meet the requirements of the USP. Upon dispensing to the patient, the pharmacist adds the appropriate amount of water. The products are stable for up to 14

Chapter 1 Pharmaceutical solutions days when refrigerated. This period usually provides sufficient time for the patient to complete the administration of all the medication.
2 S o l l u t t i i o n b y c h e m i i c a l l r e a c t t i i o n
ƒ These solutions are prepared by reacting two or more solutes with each other in a suitable solvent. An example is aluminum subacetate topical solution USP.
ƒ Aluminum sulfate (145 g) is dissolved in 600 ml of cold water. The solution is filtered, and precipitated calcium carbonate (70 g) is added, in several portions, with constant stirring. Acetic acid (160 ml) is added slowly and the mixture set aside for
24 hours. The product is filtered and the magma on the buchner filter is washed with cold water until the total filtrate measures 1000 ml.
Aluminum subacetate topical solution is used as astringent wash or wet dressing for topical application in treatment of certain eczematous condition of the skin.
3 S o l l u t t i i o n b y e x t t r a c t t i i o n
ƒ Drugs or pharmaceutical necessities of vegetable or animal origin often are extracted with water or with water containing other substances. Preparations of this type may be classified as solutions but more often, are classified as extracts.
•
( ( A ) ) A Q U E O U S S O L U T I I O N
A solution is a homogeneous mixture that is prepared by dissolving a solid, liquid, or gas in another liquid and represents a group of preparations in which the molecules of the solute or dissolved substance are dispersed among those of the solvent. The narrower definition in this section limits the solvent to water and excludes those preparations that are sweet and/or viscid in character and nonaqueous solutions, therefore, it includes those pharmaceutical forms that are designated as water, aromatic waters, aqueous acids, solutions, douches, enemas, gargles, mouthwashes, juices, nasal solutions, otic solutions, and irrigation solutions.

Chapter 1 Pharmaceutical solutions
1) WATER
Naturally occurring waters contain dissolve minerals indigenous to the region. Such waters are described variously as mineral waters. Commonly, they are very dilute solution of calcium, magnesium, iron (III), sodium and potassium ions, having bicarbonate, sulfate, and chloride as counter ions. Hard waters are those that contain calcium and magnesium cations. a) Potable water (tap water)
ƒ Potable water is water that is fit to drink.
ƒ The overall process involves:
¾ Removal of insoluble matter through appropriate coagulating, settling, and filtering process.
¾ Destruction of pathogenic microorganisms by aeration, chlorination, or other methods.
¾ Improvement of palatability through aeration and filtration through charcoal.
ƒ Hard water contains soluble calcium and magnesium salts which cause the precipitation of soap and prevent its lathering and form scale in boilers, water pipes and autoclaves. In regions where water is excessively hard, softening is effected by adding lime (CaO) or ammonia to partially remove dissolved salts by precipitation as carbonates (Ca 2+ and Mg 2+ ) and hydroxides [iron (III)]. Standards for potable water are issued by Environmental Protection Agency (EPA). Potable water is unsuitable for certain pharmaceutical purposes due to its possible bacterial contamination and the presence of dissolved salts. b) Purified water
ƒ Purified water is prepared by distillation, ion-exchange (deionized, demineralized), reverse osmosis, or other methods.
ƒ Potable water, meeting environmental protection agency (EPA) standards, is used in its preparation. The object is the removal of dissolved solids.
ƒ Ion-exchange and reverse osmosis are particularly effective in removing electrolytes.
Distillation is not effective in the removal of week electrolytes and nonelectrolytes if they are volatile.
ƒ Purified water may be rendered sterile and pyrogen-free by repeated distillation in a still with baffle system to prevent entrainment of water droplets that carry pyrogenic substances. Pyrogen is non volatile.

Chapter 1 Pharmaceutical solutions c) Water for injection
ƒ Water for injection is water purified by distillation or by reverse osmosis, free from pyrogen.
ƒ It is intended to be used as a solvent in parenteral solutions which are to be sterilized after preparation. It is prepared in a still fitted with a baffle system to prevent entrainment of water droplets that carry pyrogenic substances. d) Sterile water for injection
ƒ Water for injection is sterilized by autoclaving in sealed containers immediately
(within 4-6 hours of collection) to prevent the development of bacteria from which pyrogens are derived. e) Water for injection free from dissolved gases
ƒ For some preparations (e.g. aminophylline injections) the water must be free from dissolved carbon dioxide, and for some preparations (apomorphine injections) the water must be free from dissolved air.
ƒ This is achieved by boiling freshly prepared apyrogenic water for 10 minutes to dispel dissolved gases and then immediately sealing into its final container for sterilization. f) Bacteriostatic water for injection
ƒ Sterile water for injection containing one or more suitable antimicrobial agents. g) Sterile water for irrigation
ƒ Water for injection that has been sterilized and suitably packaged. It contains no antimicrobial agent or other added substance.

Chapter 1 Pharmaceutical solutions
2) AROMATIC WATER o
Aromatic waters, known also as medicated waters, are clear, saturated aqueous solutions of volatile oil or other aromatic or volatile substances. Their odours and tastes are similar to those of the drugs or volatile substances from which they are prepared. They are used principally as flavored or perfumed vehicles. o
Aromatic waters prepared from essential oils, e.g. peppermint water, have been used as carminatives. Chloroform water, is used in expectorants preparations. Rose water is a perfume. o
Aromatic waters are prepared by the following methods:
1- Distillation method
ƒ The distillation method consists of placing the odoriferous portion of the plant or drug from which the aromatic water is to be prepared in a suitable still with sufficient purified water and then distilling most of the water. The aqueous phase, which may require further clarification, is the product.
ƒ Orange flower water is an example of aromatic water which is prepared directly from fresh plant material and, thus cannot be prepared by any method other than distillation.
2- Solution method
ƒ In solution method the volatile substance is agitated with purified water for a period of 15 minutes.
ƒ The mixture is then set aside for at least 12 hours, to ensure saturation, before it is filtered through wetted filter paper.
ƒ A large excess of solute is used (2 ml or 2 gm, liquid or solid as the case may be, per liter) in order to obtain a saturated solution. The filter paper must be wet to prevent the passage of excess oil into the filtrate and to eliminate absorption of the dissolved aromatics by the filter.
ƒ Chloroform water is prepared by solution method. No clarification problem exists in this case, since a slight excess of chloroform must remain in the bottom, as it is heavier than water. The high volatility of chloroform creates an equilibrium of loss and restoration of strength by evaporation.

Chapter 1 Pharmaceutical solutions
As chloroform is heavier than water a slight excess will remain at the bottom, this excess will help in creating a loss and restoration equilibrium of strength.
3- Alternate solution method
ƒ Clarification and time consumed present difficulties in the solution method.
ƒ An alternative method is applied, in which the volatile material is mixed thoroughly with 15 gm. of purified talc. This mixture is agitated with a liter of purified water for
10 minutes, prior to filtration.
ƒ The talc or other inert material functions as both a filter aid and a distribution agent.
¾ As distribution agent, it serves to accelerate the rate of solution by adsorbing and facilitating the breaking up of the aromatic substance into fine particles, thus increasing the surface area exposed to solvent action.
¾ As filter aid, it farcicalities the clarification of the solution.
ƒ The time-saving factor is an important advantage.
4- Dilution method
ƒ In an attempt to obviate the difficulties involved in the clarification of aromatic waters, formulas have been developed for concentrates which are designed to be diluted with an appropriate volume of water when needed.
ƒ An alcoholic solution of the essential oil is mixed with water and talc. The mixture is agitated; after several hours it is filtered. The concentrate contains between 50 and 55

Chapter 1 Pharmaceutical solutions per cent alcohol by volume. One volume of concentrate is diluted with 39 volumes of water, producing aromatic water which contains less than 1.5 per cent of alcohol.
ƒ Concentrated waters, such as peppermint, dill, cinnamon, and caraway, may be prepared as follows:
Essential oil
Alcohol 90%
Talc
Water to
2 ml.
60 ml
5 g.
100 ml.
¾ Dissolve 2 ml. of the volatile oil in 60 ml of 90% ethanol.
¾ Add sufficient purified water in successive small portions to produce 100 ml.
¾ Shake vigorously after each addition.
¾ Add 5 g. of sterilized purified talc, shake occasionally for several hours, and filter.
ƒ The aromatic water is prepared by diluting the concentrated with 39 times its volume of water.
Preservation
Aromatic waters will deteriorate with time and should, therefore, be made in small quantities, protected from intense light and excessive heat, and stored in airtight, lightresistant containers.
3) AQUEOUS ACIDS
The official inorganic acids and certain organic acids, although of minor significance as therapeutic agents, are of great importance in chemical and pharmaceutical manufacturing.
This is especially true of acetic, hydrochloric, and nitric acids. o Incompatibilities
ƒ Acid and acid salts decompose carbonates with liberation of carbon dioxide; in a closed container, sufficient pressure may be developed to produce an explosion.

Chapter 1 Pharmaceutical solutions
HCl + CaCO
3
CaCl
2
+ CO
2
+ H
2
O
ƒ Inorganic acids react with salts of organic acids to produce the free organic acid and a salt of the inorganic acid. If insoluble, the organic acid will be precipitated.
Thus, salicylic acid and benzoic acid are precipitated from solutions of salicylates and benzoates. Boric acid likewise is precipitated from concentrated solutions of borates.
+ HCl + NaCl
Sodium Benzoate Benzoic acid
(Water soluble) (Water insoluble)
ƒ By a similar reaction, certain soluble organic compounds are converted into an insoluble form. Phenobarbital sodium, for example, is converted into
Phenobarbital that will precipitate in aqueous solution. o Diluted acids
ƒ The diluted acids in the USP are aqueous solutions of acids, of a suitable strength
(usually 10% w/v but diluted acetic acid is 6% w/v) for internal administration or for the manufacture of other preparations.
ƒ The strengths of the official undiluted acids are expressed as percentages in weight (w/w), whereas the strengths of the official diluted acids are expressed as percent in volume (w/v). Therefore, it becomes necessary to consider the specific gravities of the concentrated acids when calculating the volume required to make a given quantity of diluted acid.
ƒ Diluted hydrochloric acid USP has been used in the treatment of achlorhydria.
However, it may irritate the mucous membrane of the mouth and attach the enamel of the teeth. The usual dose is 2 to 4 ml, well-diluted with water. In the treatment of achlorhydria no attempt is made to administer more than a reliefproducing dose.

Chapter 1 Pharmaceutical solutions
4) DOUCHES o
A douche is an aqueous solution directed against a part or into a cavity of the body that function as a cleansing or antiseptic agent. o
Douches are usually directed to appropriate body part by using bulb syringes. o
Douches are most frequently dispensed in the form of a powder with directions for dissolving in a specified quantity of water (usually warm). However, tablets for preparing solutions are available (e.g., Dobell’s solution tablets) or the solution may be prepared by the pharmacist. If powders or tablets are supplied, they must be free from insoluble material in order to produce a clear solution. Tablets are produced by the usual process but any lubricants or diluents used must be readily soluble in water.
Boric acid may be used as a lubricant and sodium chloride normally is used as a diluent. Tablets deteriorate on exposure to moist air and should be stored in airtight containers. o
Douches are not official as a class of preparations but several substances in the compendia frequently are employed as such in weak solutions; for example, benzalkonium chloride is used in various douches and compound sodium borate solution NFXI (Dobell’s) has been used as a nasal or pharyngeal douche. o Types of douches:
1) Eye douches:
• Used to remove foreign particles and discharges from the eyes.
• Method of application: directed gently at an oblique angle and allowed to run from the inner to the outer corner of the eye.
2) Pharyngeal douches:
• Used to prepare the interior of the throat for an operation and cleanse it in suppurative conditions.
3) Nasal douches:
• Used for cleansing of the nasal cavity
4) Vaginal douches:
• The most common type of douches.
• Used for cleansing the vagina and for hygienic purposes.
• Supplied as a liquid concentrates or powders, which may be prepared in bulk or as single-use packages, that require to be diluted or dissolved in the appropriate amount of warm water prior to use.

Chapter 1 Pharmaceutical solutions
• The ingredients used in vaginal douches include:
¾ Antimicrobial agent such as benzalkonium chloride, parabens or chlorothymol.
¾ Anesthetics or antipruritics such as phenol or menthol.
¾ Astringents such as zinc sulfate or potassium alum.
¾ Surface-active agents such as sodium lauryl sulfate.
¾ Chemicals to alter the pH such as sodium bicarbonate or citric acid also are used.
5) ENEMAS o
Enema preparations are rectal injections employed to:
ƒ Evacuate the bowel (evacuation enemas).
ƒ Influence the general system by absorption, or to affect a local disease
(retention enemas).
ƒ They may possess anthelmintic, nutritive, sedative, or stimulating properties, or they may contain radiopaque substances for roentgenographic examination of the lower bowel.
“Enema may contain radiopaque substances for roentgenographic examination of the lower bowel” o
Sodium chloride, sodium bicarbonate, sodium mono-hydrogen phosphate, and sodium dihydrogen phosphate are used in enemas to evacuate the bowel. These substances may be used alone, in combination with each other, or in combination with irritants such as soap.

Chapter 1 Pharmaceutical solutions o
Enema of soap BPC 1963 is prepared by dissolving 50 g of soft soap in sufficient purified water to make 1000 ml of enema. o
Sodium phosphates enema USP contains 6 g of dibasic sodium phosphate heptahydrate and 16 g of monobasic sodium phosphate monohydrate in each 100 ml. o
Evacuation enemas usually are given at body temperature in quantities of 1 to 2 pt injected slowly with a syringe (pint; pt = 473 ml). o
An official retention enema used for systemic purposes is aminophylline (for bronchial asthma and reduction of coughing). o
Retention enemas are to be retained in the intestine and should not be used in larger quantities than 150 ml for an adult. Usually, the volume is considerably smaller such as a few ml. o
Microenema is a term used to describe these small-volume preparations. Vehicles for retention microenemas have been formulated with small quantities of ethanol and propylene glycol. A number of other drugs such as valproic acid, indomethacin, and metronidazole have been formulated as microenemas for the purpose of absorption.
Sulphamerazine rectal enema has been administered for the treatment of ulcerative colitis. o
Starch enema may be used either by itself or as vehicle for other forms of medication.
A thin paste is made by triturating 30 g of powdered starch with 200 ml of cold water.
Sufficient boiling water is added to make 1000 ml of enema. The preparation then is reheated to obtain a transparent liquid.
6) GARGLES o
Gargles are aqueous solutions frequently containing antiseptics, antibiotics, and/or anesthetics used for treating the pharynx and nasopharynx by forcing air from the lungs through the gargle that is held in the throat; subsequently, the gargle is expectorated.

Chapter 1 Pharmaceutical solutions o
Many gargles must be diluted with water prior to use. o
Although mouthwashes are considered as a separate class of pharmaceuticals, many are used as gargles, either as it is, or diluted with water. o
Rapid relief of pharyngeal and oral pain was obtained when solution containing benzocaine (a topical anesthetic) and cetylpyridinium chloride (antiseptic), was used as a gargle.
7) MOUTHWASHES o
Mouthwashes are aqueous solution often in concentrated form containing one or more active ingredients and excipients. o
Mouthwashes can be used for two purposes, therapeutic and cosmetic:
ƒ Therapeutic rinses or washes can be formulated to reduce plaque, gingivitis, dental caries and stomatitis.
ƒ Cosmetic mouthwashes may be formulated to reduce bad breath through the use of antimicrobial and/or flavoring agents. o
Recent information indicates that mouthwashes are being used as a dosage form for a number of specific problems in the oral cavity; for example, mouthwashes containing a combination of antihistamines, hydrocortisone, nystatin and tetracycline have been prepared for the treatment of stomatitis, a painful side effect of cancer therapy. o
Cetylpyridinium chloride and dibucaine hydrochloride mouthwashes provide satisfactory relief of pain in patients with ulcerative lesions of the mouth. o
Mouthwashes containing carbenoxolone are highly effective dosage forms for the treatment of orofacial herpes simplex infections. o Mouthwashes generally contain four groups of excipients:
1) Alcohols
Alcohol is often present in the range of 10 to 20%. It enhances the flavor, provides a certain sharpness to the taste, aids in masking the unpleasant taste of active ingredients, functions as a solubilizing agent for some flavoring agents, and may function as a preservative. Humectants such as glycerin and sorbitol may form
5 to 20% of the mouthwash.
2) Surfactants
Surfactants of the nonionic class may be used in a concentration range of 0.1 to
0.5%. An anionic surfactant occasionally used is sodium lauryl sulfate. Surfactants are used because they aid in the solubilization of flavors and in the removal of

Chapter 1 Pharmaceutical solutions debris by providing foaming action. Cationic surfactants such as cetylpyridinium chloride are used for their antimicrobial properties, but these tend to impart a bitter taste.
3) Flavors
Flavors are used in conjunction with alcohol and humectants to overcome disagreeable tastes, at the same time flavors must be safe to use. The principle flavoring agents are peppermint, spearmint, cinnamon, wintergreen oils, menthol, or methyl salicylate.
4) Coloring agents
Coloring agents also are used in these products.
8) JUICES o
A juice is prepared from fresh ripe fruit, is aqueous in character, and is used in making syrups that are employed as vehicles. o
The freshly expressed juice is preserved with benzoic acid and allowed to stand at room temperature for several days, until the pectins that naturally are present are destroyed by enzymatic action, as indicated by the filtered juice yielding a clear solution with alcohol. o
Pectins, if allowed to remain, would cause precipitation in the final syrup. o
Examples: Cherry juice (USP 21), and Raspberry juice (USP 18). o
Artificial flavors now have replaced many of the natural fruit juices. Although they lack the flavor of the natural juice, they are more stable and easier to incorporate into the final pharmaceutical form. o
Commercial juices such as orange, apple, grape and mixed vegetables have been used recently to prepare extemporaneous preparations.
9) NASAL SOLUTIONS o
Nasal solutions are usually aqueous solutions designed to be administered to the nasal passages in drops or sprays. o
Aim of administration:
ƒ Local sympathomimetic effect, such as ephedrine sulfate or naphazoline hydrochloride nasal solution USP, to reduce nasal congestion

Chapter 1 Pharmaceutical solutions
ƒ Systemic effect, such as lypressin nasal solution USP and oxytocin nasal solution USP, administered in spray form for their systemic effect for the treatment of diabetes insipidus and milk letdown prior to breast feeding, respectively. Moreover, drugs that are absorbed poorly from the GI tract, such as gentamicin sulfate, are being administered in the form of nasal solutions to obtain appropriate blood levels. o
The aqueous nasal solutions usually are isotonic and slightly buffered to maintain a pH of 5.5 to 6.5. In addition, antimicrobial preservatives, similar to those used in ophthalmic preparations, and appropriate drug stabilizers, if required, are included in the formulation.
12) OTIC SOLUTIONS o
These solutions occasionally are referred to as aural preparations. Other otic preparations often include formulation such as suspensions and ointments for topical application in the ear. o
The main classes of drugs used for topical administration to the ear include analgesics, such as benzocaine; antibiotics, such as neomycin; and anti-inflammatory agents, such as cortisone. o
The USP preparations include antipyrine and benzocaine otic solution. The neomycin and polymyxin B sulfates and hydrocortisone otic solutions may contain appropriate buffers, solvents, and dispersants usually in an aqueous solution. o
The main solvents used in these preparations include glycerin or water. The viscous glycerin vehicle permits the drug to remain in the ear for a long time. Anhydrous glycerin, being hygroscopic, tends to remove moisture from surrounding tissues, thus reducing swelling. Viscous liquids like glycerin or propylene glycol are used either alone or in combination with a surfactant to aid in the removal of cerumen (ear wax). o
Sodium bicarbonate ear-drops BP may be used if wax is to be removed from the ear.
This preparation contains:
Sodium bicarbonate
Glycerin
5 g
30 ml
Purified water to 100 ml

Chapter 1 Pharmaceutical solutions o
To provide sufficient time for aqueous preparations to act, it is necessary for patients to remain on their side for a few minutes so the drops do not run out of the ear. o
Otic preparations are dispensed in a container that permits the administration of drops.
13) IRRIGATION SOLUTIONS o
Irrigation solutions are used to wash or bathe surgical incision, wound, or body tissues. o
Because they come in contact with exposed tissue, they must meet stringent requirements of the USP such as sterility, total solids, and bacterial endotoxins. o
These products may be prepared by dissolving the active ingredient in water for injection. o
They are packaged in single-dose glass containers, or suitable plastic containers, and then sterilized. o
A number of irrigations are described in the USP, e.g., acetic acid irrigation for bladder irrigation, dimethyl sulfoxide irrigation for relief of internal cystitis, neomycin and polymyxin B sulfates solution for irrigation for infection, and sodium chloride irrigation for washing wounds.
( ( B ) ) S W E E T O R O T H E R V I I S C I I D A Q U E O U S S O L U T I I O N S
Solutions that are sweet or viscid include syrups, honeys, mucilages, and jellies. All of these are viscous liquids or semisolids. The basic sweet or viscid substances giving body to these preparations are sugars, polyols or polysaccharides (gums).
1) SYRUPS o
Syrups are concentrated solutions of sugar such as sucrose in water or other aqueous liquid. o
When purified water alone is used in making the solution of sucrose, the preparation is known as Syrup, or simple syrup. o
Syrup USP is a 85% w/v or an approximately 65% w/w sucrose solution with a specific gravity of 1.313. It is used as sweetening agent and a vehicle for other syrups. o
Syrup USP is a self-preserved solution with a minimum chance of crystallization.

Chapter 1 Pharmaceutical solutions o
Syrup BP contains 66.7% w/w of sucrose as the solute in 33.3% w/w of water as the solvent. o
The concentration of sucrose in syrup is critical in the control of microorganisms growth. Dilute sucrose solutions are excellent media for microorganisms. Some syrups do not contain a preservative as the concentration of sucrose approaches saturation and the syrups are self-preserved. o
Additives:
ƒ Polyols, such as glycerin or sorbitol, may be added to retard crystallization of sucrose or to increase the solubility of added ingredients.
ƒ Alcohol often is included as a preservative and also as a solvent for flavors.
ƒ Further resistance to microbial attack can be enhanced by incorporating antimicrobial agents. o
When the aqueous preparation contains some added medicinal substance, the syrup is called medicated syrup. o
A flavored syrup is one that usually is not medicated, but rather contains various aromatic or pleasantly flavored substances and is intended to be used as a vehicle or flavor for prescriptions, such as acacia, cherry, cocoa, and orange USP 21. o
When heat is used in the preparation of syrups, inversion of a slight portion of the sucrose may take place. This reaction is termed inversion because invert sugar
(dextrose plus levulose) is formed.
C
12
H
22
O
11
+ H
2
O C
6
H
12
O
6
+ C
6
H
12
O
6
Sucrose Dextrose Levulose
(Glucose) (Fructose)
¾ The speed of inversion is increased greatly by the presence of acids. The levulose formed during inversion is sweeter than sucrose, and thus the resulting syrup is sweeter than the original syrup. The levulose formed during the hydrolysis also is responsible for the darkening of syrup. o
If a sugar solution is excessively heated, the sweet taste is destroyed and a dark brown liquid is formed. This process is known as caramelization. o Methods of preparation:
ƒ Syrups are prepared in various ways; the choice of the proper method depends on the physical and chemical characteristics of the substances entering into the preparation.

Chapter 1 Pharmaceutical solutions
1- Solution with heat
This is the usual method of making syrups when the valuable constituent is neither volatile nor injured by heat, and when it is desirable to make the syrup rapidly. The sucrose usually is added to the purified water or aqueous solution and heated until solution is affected, then it is strained and sufficient purified water is added to make the desired weight or volume.
Excessive heating of syrups at the boiling temperature is undesirable because more or less inversion of the sucrose occurs with an increased tendency to ferment.
Syrups cannot be sterilized in an autoclave without some caramelization. This is indicated by a yellowish or brownish color resulting from the formation of caramel by the action of heat upon sucrose.
2- Agitation without heat
This process is used in those cases where heat would cause the loss of valuable, volatile constituents. In making quantities up to 2000 ml the sucrose should be added to aqueous solution in a bottle of about twice the size required for the syrup.
This permits active agitation and rapid solution. Stoppering the bottle is important, as it prevents contamination and loss during the process.
3- Addition of a medicating liquid to syrup
This method is used in those cases in which fluidextracts, tinctures, or other liquids are added to syrup to medicate it. Syrups made in this way usually develop precipitates because alcohol is often an ingredient of the liquids used, and the resinous and oil substances dissolved by the alcohol precipitate when mixed with the syrup, producing unsightly preparations.
A modification of this process, frequently adopted, consist of mixing the fluidextract or tincture with the water, allowing the mixture to stand to permit the separation of insoluble constituents, filtering and then dissolving the sucrose in the filtrate. It is obvious that this procedure is not permissible when the precipitated ingredients are the valuable medicinal agents.
4- Percolation
In this procedure, purified water, or an aqueous solution, is permitted to pass slowly through a bed of crystalline sucrose in a cylindrical percolator, thus

Chapter 1 Pharmaceutical solutions dissolving it and forming a syrup. A coarse granular sugar must be used; otherwise it will coalesce into a compact mass, which the liquid cannot permeate.
5- Reconstitution
To improve stability and minimize microbial contamination dry syrup formulations can be prepared and purified water USP added just prior to dispensing or use. o
Preservation of syrup
ƒ Syrup USP (85%w/v) is a self-preserved solution with a minimum chance of crystallization.
ƒ Syrup should be made in quantities that can be consumed within a few months.
The USP states that syrups may contain preservatives.
ƒ Glycerin, methylparaben, benzoic acid, and sodium benzoate may be used to prevent bacterial and mold growth.
ƒ Combinations of alkyl esters of p-hydroxybenzoic acid are effective inhibitors of yeasts that have been implicated in the contamination of commercial syrups. o Syrups prepared from juices
ƒ Examples: blackberry, pineapple, and strawberry syrups.
ƒ Procedures for making raspberry syrup BP 1988:
¾ One volume of the concentrated raspberry juice is diluted with 11 volumes of syrup. o Syrups containing pharmaceuticals
ƒ Syrups, either as a syrup or as a flavored syrup, are useful for preparing liquid oral dosage forms from not only the pure drug, as described above, but also injections, capsules, or tablets if the pure drug is not readily available. On one hand, if the drug and all the excipients in the preparation, such as injectables or capsules, are water soluble, a solution will frequently result if a syrup is prepared.
On the other hand, if the preparation to be used contains water-insoluble ingredients, as is usually the case with tablets and some capsules, a suspension will be formed.

Chapter 1 Pharmaceutical solutions
2) LINCTUSES o
Linctus is a viscous preparation usually prescribed for the relief of cough. o
It usually consists of a simple solution of the active agent in a high concentration of sucrose often with other sweetening agents. o
This type of products, which is also designed to be administered in multiples of 5 ml should be sipped slowly and do not diluted beforehand. o
The syrup content has a demulcent action on the mucous membranes of the throat. o
For diabetic use the sucrose is usually replaced by sorbitol and /or synthetic sweeteners. o
Examples are Codeine Linctus in sucrose syrup PC (11th ed) & Diabetic Codeine
Linctus in sorbitol solution, PC (11 th ed).
3) HONEYS o
Honeys are thick liquid preparations somewhat allied to the syrups, differing in that honey, instead of syrup is used as a base. o
They are unimportant as a class of preparations today, but at one time, before sugar was available and honey was the most common sweetening agent, they were used widely. o
The BP has a monograph for purified honey and the BP listed one preparation for coughs containing honey. Squill oxymel contains squill, water, acetic acid, and honey and is prepared by a maceration process.
4) MUCILAGES o
The official mucilages are thick, viscid, adhesive liquids, produced by dispersing gum in water, or by extracting the mucilaginous principles from vegetable substances with water. o
All mucilages are prone to decomposition, showing appreciable decrease in viscosity on storage, they should never be made in quantities larger than can be used immediately, unless a preservative is added. Acacia mucilage NF12 contains benzoic acid and tragacanth mucilage BPC (1973) contains alcohol and chloroform water. o
Mucilages are used primarily to aid in suspending insoluble substances in liquids; their colloidal character and viscosity help prevent immediate sedimentation. o
Several synthetic mucilage-like substances such as polyvinyl alcohol, methylcellulose, carboxymethylcellulose and related substances are used at the

Chapter 1 Pharmaceutical solutions appropriate concentration as mucilage substitutes and emulsifying and suspending agents. o
Methylcellulose is used widely as a bulk laxative because it absorbs water and swells to a hydrogel in the intestine. o
Synthetic gums are non-glycogenic (not converted to glucose in the body) and may be used in the preparation of diabetic syrups. o
Sodium carboxymethyl- cellulose (0.25 to 1%) of a medium grade in water is generally suitable for preparing a suspending vehicle.
5) JELLIES o
Jellies are a class of gels in which the structural coherent matrix contains a high portion of liquid, usually water. o
They are similar to mucilages, in that they may be prepared from similar gums, but they differ from the latter in having a jelly-like consistency. o
A whole gum of the best quality, rather than a powdered gum, is desirable to obtain a clear preparation of uniform consistency. Tragacanth is the gum used in the preparation of ephedrine sulfate jelly NF 12. o
These preparations also may be formulated with water from acacia, chondrus, gelatin, carboxymethylcellulose, hydroxyethylcellulose, and similar substances. o
Uses: jellies are used as lubricants for surgical gloves, catheters, and rectal thermometers. Lidocaine hydrochloride jelly USP is used as a topical anesthetic.
Therapeutic vaginal jellies are available and certain jelly-like preparations are used for contraceptive purposes, which often contain surface-active agents to enhance the spermatocidal properties of the jelly. Aromatics, such as methylsalicylate and eucalyptol, often are added to give the preparation a desirable odor.
o
Jellies are prone to microbial contamination and therefore contain preservatives; for example, methyl p-hydroxybenzoate is used as a preservative in a base for medicated jellies. o
One base contains sodium alginate, glycerin, calcium gluconate, and water. The calcium ions cause a cross-linking with sodium alginate to form a gel of firmer consistency.

Chapter 1 Pharmaceutical solutions
( ( C ) ) N O N A Q U E O U S S O L U T I I O N S
It is difficult to evaluate fairly the importance of non-aqueous solvents in pharmaceutical processes. However, pharmaceutical preparations, and, in particular, those intended for internal use, rarely contain more than minor quantities of the organic solvents.
Chloroform has been an ingredient in a number of cough syrups in the past but it has been banned in the US by the FDA in manufactured products intended for internal use. Solvents such as acetone, benzene, and petroleum ether must not be ingredients in preparations intended for internal use.
Products of commerce for internal use may contain solvents such as ethanol, glycerin, propylene glycol, certain oil, and liquid paraffin. Preparations intended for external use may contain solvents in addition to those just mentioned, namely isopropyl alcohol, polyethylene glycols, various ethers, and certain esters.
This section is, therefore devoted to groups of non-aqueous solutions: the alcoholic or hydroalcoholic solutions (e.g., elixirs and spirits), ethereal solutions. (e.g., collodions), glycerin solutions (e.g., glycerins), oleaginous solutions (e.g., liniments, oleovitamins, and toothache drops), inhalations, and inhalants.
1) COLLODIONS o
Collodions are liquid preparations containing pyroxylin (a nitrocellulose) in a mixture of ethyl ether and ethanol. o
They are applied to the skin by means of a soft brush or other suitable applicator and, when the ether and ethanol have evaporated, leave a film of pyroxylin on the surface. o
The official medicated collodion, salicylic acid collodion USP, contains 10% w/v of salicylic acid in flexible collodion USP and is used as a keratolytic agent in the treatment of corns and warts.
Collodions are applied to the skin by means of a soft brush and are mainly used in the treatment of corns and warts

Chapter 1 Pharmaceutical solutions o
Collodion USP and flexible collodion USP are water-repellent protectives for minor cuts and scratches. Collodion is made flexible by the addition of castor oil and camphor. o
Collodion has been used to reduce or eliminate the side effects of fluorouracil treatment of solar keratoses. o
Vehicles other than flexible collodion, such as a polyacrylic base, have been used to incorporate salicylic acid for the treatment of warts with less irritation.
2) ELIXIRS o
Elixirs are clear, pleasantly flavored, sweetened hydroalcoholic liquids intended for oral use. o
The main ingredients in elixirs are ethanol and water but glycerin, sorbitol propylene glycol, flavoring agent, preservatives, and syrups often are used in the preparation of the final product. The solvents are often used to increase the solubility of the drug substance in the dosage form. o
Elixirs are more fluid than syrups, due to the use of less viscous ingredients such as alcohol and the minimal use of viscosity-improving agents such as sucrose. o
They are used as flavors and vehicles for drug substances (e.g. aromatic elixir USP).
o
Examples of medicated elixirs:
ƒ Dexamethasone elixir USP
ƒ Phenobarbital elixir USP o
Occasionally, certain adverse effects (e.g., mucosal erosions) may be eliminated or reduced if the active drug (e.g. potassium chloride) is administered in elixir rather than in a solid dosage form. o
The distinction between some of the medicated syrups and elixirs is not always clear however elixir must contain alcohol. o
Elixirs also may contain glycerin and syrup. These may be added to increase the solubility of the medicinal agent, for sweetening purposes or to decrease the pharmacological effects of the alcohol. Some elixirs contain propylene glycol. Claims have been made for this solvent as a satisfactory substitute for both glycerin and alcohol. o
An elixir may contain both water- and alcohol-soluble ingredients. If such is the case, the following procedure is indicated:
ƒ Dissolve the water-soluble ingredients in part of the water.

Chapter 1 Pharmaceutical solutions
ƒ Add and solubilize the sucrose in the aqueous solution.
ƒ Prepare alcoholic solution containing the other ingredients.
ƒ Add the aqueous phase to the alcoholic solution, filter, and make to volume with water.
¾ Sucrose increases viscosity and decreases the solubilizing properties of water and so must be added after primary solution has been affected.
¾ A high alcoholic content is maintained during preparation by adding the aqueous phase to the alcoholic solution. o
Elixirs that contain therapeutically active compounds are known as medicated elixirs.
Phenobarbital elixir is an example of a medicated elixir. o
Incompatibilities:
ƒ Because elixirs contain alcohol, incompatibilities of this solvent are an important consideration during formulation.
ƒ Alcohol precipitates tragacanth, acacia, and agar from aqueous solutions.
ƒ If an aqueous solution is added to an elixir, a partial precipitation of alcohol soluble ingredients may occur. This is due to reduced alcoholic content of the final preparation.
3) GLYCERIDES o
Glycerins or glycerites are solution or mixtures of medicinal substances in not less than 50% by weight of glycerin. Most of the glycerins are extremely viscous and some are of a jelly-like consistency. Few of them are used extensively. o
Glycerin is used as the sole solvent for the preparation of antipyrine and benzocaine otic solution USP. o
As noted under otic solution, glycerin alone is used to aid in the removal of cerumen. o
Externol, a commercial product, contains 5% carbamide peroxide (urea hydrogen peroxide) in glycerin, has shown superior qualities in dispersing ear wax. o
A glycerin base was chosen as the optimum solvent for an otic preparation in a study involving the stability and antimicrobial activity of kanamycin sulfate otic drops. o
Glycerins are hygroscopic and should be stored in tightly closed containers.

Chapter 1 Pharmaceutical solutions
4) INHALATIONS AND INHALANTS a) Inhalations o
Inhalation preparations are so used or designed that the drug is carried into the respiratory tree of the patient. The vapor or mist reaches the affected area and give prompt relief from the symptoms of bronchial and nasal congestion. The USP defines Inhalations in the following way: “Inhalations are drugs or solutions or suspensions of one or more drug substances administered by the nasal or oral respiratory route for local or systemic effect” b) Inhalants o
The USP defines “inhalants” as follows: “A special class of inhalations termed
“inhalants” consists of drugs or combinations of drugs that, by virtue of their high vapor pressure, can be carried by an air current into the nasal passage where they exert their effect. “ o
The container from which the inhalant is administered in known as an inhaler. o
Examples are Propylhexedrine inhalant USP and tuaminoheptane inhalant USP 22.
Both of these drugs are vasoconstrictors used to relieve nasal congestion. o
Inhalers that come in contact with the mouth or nasal passages become contaminated by bacteria, thus they should be restricted to personal use. o
Another inhalant, amyl nitrite USP, is very flammable and should not be used where it may be ignited. It is packaged in sealed glass vials in a protective gauze. Upon breaking the vial, the gauze absorbs the drug that is then inhaled for the treatment of angina pain.
5) LINIMENTS o
Liniments are solutions or mixtures of various substances in oil, alcoholic solutions of soap, or emulsions and may contain suitable antimicrobial preservatives. These preparations that may be liquid or semiliquid are intended for external application and should be so labeled. They were once called embrocations. o
Liniments usually are applied with friction and rubbing of the skin:
ƒ The oil or soap base provides ease of application and massage.

Chapter 1 Pharmaceutical solutions
ƒ Alcoholic liniments are used for their rubefacient, counterirritant, mildly astringent and penetrating effect as they penetrate the skin more readily than oil base liniments.
ƒ The oily liniments, therefore, are milder in their action but are more useful when massage is required. o
Depending on their ingredients, such liniments may function solely as protective coatings. Liniments should not be applied to skin that is bruised or broken. o
White liniment BP
Oleic acid 85 ml
Dilute ammonia solution 45 ml
Ammonium chloride 12.5 g
Purified water 625 ml o
Other liniments contain antipruritics, astringents, emollients, or analgesics and are classified on the basis of their active ingredient. Here is an example.
ƒ Compound calamine liniment
Calamine
Zinc oxide
100 g
50 g
Wool fat 25 g
Zinc stearate 25 g
Yellow soft paraffin 250 g
Liquid paraffin 550 g o
It is essential that these applications be marked clearly “For External Use Only”. o
Liniments containing a nonsteroidal anti-inflammatory agent are being investigated for their anti-inflammatory and analgesic effect.

Chapter 1 Pharmaceutical solutions
6) OLEOVITAMINES o
Oleovitamines are fish-liver oils diluted with edible vegetable oil or solutions of the indicated vitamins or vitamin concentrates (usually vitamin A and D) in fish-liver oil.
The definition is broad enough to include a wide variety of marketed products.
Oleovitamin A and D are official in the USP.
7) SPIRITS o
Spirits, sometimes known as essences, are alcoholic or hydroalcoholic solutions of volatile substances. Like the aromatic waters, the active ingredient in the spirit may be a solid, liquid, or gas. o
Some spirits are used internally for their medicinal value, a few medicinally by inhalation and a large number as flavoring agents. The latter group provides a convenient and ready means of obtaining the volatile oil in the proper quantity. For example, a spirit or spirit-like preparation may be used in the formulation of aromatic waters or other pharmaceuticals that require a distinctive flavor. o
Spirits usually contain high alcohol content and consequently should be kept away from an open flame. o
Methods of preparation:
1) Simple solution
This is the method by which the majority of spirits are prepared. Aromatic ammonia spirit USP is official and prepared by simple solution method.
2- Solution with maceration
In this procedure, the leaves of a drug are macerated in purified water to extract water-soluble matter. They are expressed and the moist, macerated leaves are added to a prescribed quantity of alcohol. The volatile oil is added to the filtered liquid.
Peppermint spirit USP is made by this process.
Peppermint oil 100 ml
Peppermint, coarse powder 10 ml
Alcohol, q.s. 1000 ml
Sig.: Peppermint spirit.
¾ Peppermint spirit is prepared by maceration and solution.

Chapter 1 Pharmaceutical solutions
¾ The peppermint leaves (coarse powder) are macerated for 1 hour with water to remove tannins and other unwanted water-soluble substances. The leaves are expressed or squeezed out, and while moist they are added to alcohol. The leaves are macerated with agitation in alcohol for 6 hours to extract the chlorophyll, which imparts the green color to the spirit. After filtering the mixture, peppermint oil is dissolved in the filtrate.
8) TOOTHACHE DROPS o
Toothache drops are preparations used for temporary relief of toothache by application of a small pledget of cotton saturated with the product into the tooth cavity. o
Anesthetic compounds include clove oil, eugenol, or benzocaine; other ingredients include camphor, creosote, menthol, and alcohol. Clove oil, containing a high concentration of eugenol, which is the main constituent, has been considered safe and effective for toothache. o
These preparations no longer are recognized officially. Furthermore, dentists do not recommend the use of toothache drops if the patient has ready access to adequate dental services. o
Some preparations may damage the gums and produce complications more sever than the original toothache However, many areas do not have adequate dental services and the pharmacist will, of necessity, handle these preparations; the patient should be warned of possible hazards associated with their use.