PIP 213 Lecturer: Dr. Nwachukwu, N. Mixtures Pharmaceutical mixtures are liquid oral preparation consisting of one or more medicaments suspended or diffused an aqueous vehicle. They are usually freshly or recently prepared and are used fairly quickly, usually within a month for short term therapy like cough, diarrhoea, constipation etc. Mixtures in Pharmacy are aqueous liquid preparations which contain suspended, insoluble, solid substances and are intended for internal use. The insoluble particles may be held in suspension by the use of suitable suspending or thickening agents since the insoluble substance does not make the mixture to be very viscous. Mixtures are further classified into five different groups 1. Simple mixtures containing soluble substances 2. Mixtures containing diffusible solids; that is, solids which do not dissolve in water, but may be mixed by shaking in non-aqueous vehicles. As a result, the powdered particles are evenly distributed throughout the liquid for a sufficient period of time to permit withdrawal of accurate dose of the medicament. 3. Mixtures containing indiffusible solids; that is, solids which are not dissolved in water and do not remain uniformly distributed in the solvent for sufficiently a long period of time. The particles are seen as sediments at the bottom of the container containing the formulation. They quickly redisperse on agitation to permit withdrawal of accurate doses of the medicament. 4. Mixtures containing precipitate forming liquids and 5. Mixtures containing slightly soluble liquids. Linctuses Linctuses are viscous oral liquids containing one or more medicament dissolved in a vehicle that usually contains high proportion of sucrose or other sugars. They are chiefly used as demulcent, expectorant or sedative principally in the treatment or relief of cough. As such, linctus is intended to be sipped slowly in small doses and allowed to trickle down the throat in an undiluted form. This gives maximum and prolonged effect of medicament in the throat. Elixirs are clear, flavored, sweetened, hydro alcoholic liquid oral preparations that usually contain either potent or unpleasant-tasting drugs. They may be medicated or non-medicated. Compared to syrups, elixirs are usually less sweet and less viscous because they contain a lesser amount of sugar. Because of their hydroalcoholic character, elixirs are better able than are syrups to maintain both water-soluble and alcohol-soluble components in solution. Syrups Syrups are concentrated aqueous solutions containing one or more sugar components, chiefly sucrose, or sugar substitute. The concentration of sugar in syrup is 66.7 % W/W. Syrups may be medicated or non-medicated. The non-medicated syrup which is often referred to as simple syrups are used as vehicles for medicinal substances to be added later, either in the extemporaneous compounding of prescriptions or in the preparation. Creams Creams can be described as viscous semi-solid, opaque or thick emulsions of oil and water intended for external application to the skin. However, their use is not restricted to the skin as they can be applied to some mucous membranes (internal surfaces) such as the vagina and rectum. Traditionally, the terminology cream has been applied to semi-solids that possess a relatively fluid consistency formulated as either water-in-oil (e.g., cold cream) or oil-in-water emulsions. However, in recent times, the term has been restricted to products consisting of oilin-water emulsions or aqueous dispersions of long-chain fatty acids or alcohols that are water washable and more cosmetically and aesthetically acceptable. Creams can be used for administering drugs via the dermal or vaginal route or through any other route where it has pharmaceutical relevance. Thus creams can be cosmetic or medical. The medical creams consist of medicaments dissolved or dispersed in water-removable (varnishing cream) or emollient bases. They are classified as oil in water (o/w) or aqueous creams and water in oil (w/o) or oil creams. Oil in water (o/w) creams which are composed of small droplets of oil dispersed in a continuous water phase, while water-in-oil (w/o) creams which are composed of small droplets of water dispersed in a continuous oily phase Creams are emulsions with a more viscous or thicker texture that contain up to or more than 35 % water or volatile components and less than 50 % hydrocarbons, waxes, or polyols as vehicles. They may also contain one or more drug substances dissolved or dispersed in a suitable cream base. Some water miscible bases that possess a complex matrixlike physical structure are also referred to as creams. Oil and water creams such as varnishing creams when applied on the skin causes evaporation of the water leading to the concentration of the water soluble drugs in the adhering to the films. Creams are usually applied to moist weeping lesions as they have some kind of a drying effect in that the fluids will be miscible with the aqueous external phase of the creams. Bland creams are used for their emollient, cooling and moistening effects on the skin while medicated creams are used for drug delivery aimed at therapeutic or prophylactic activity. Examples of creams include cleansing creams, varnishing creams, face creams, shaving creams, hand creams and body creams. Ointment Ointments are soft semi solid preparations meant for external application to the skin or mucuous membrane. They usually contain a medicament dissolved, suspended or emulsified in the base. Ointments are used for their emollient and protective action to the skin. Examples are compound benzoic acid ointment, cetrimide emulsifying ointment etc. Ophthalmic ointments These meant for use in the eye. Usually they are sterile and free from irritation. They should bepacked in sterile containers which should keep the preparation sterile until the whole of it is used up. E.g. chloramphenicol ointment and penicillin ointment. Collodions Collodions are the liquid preparations meant for external application to the skin. They are convenient applications for small cuts and abrasions and are also used when a prolonged contact between the skin and the medicament is required. The vehicle used is volatile and evaporates on application to the skin, leaving a flexible, protective film covering at the site of application. They are usually applied with a brush or rod. The constituents of flexible collodion are pyroxillon, castor oil, and alcohol in solvent ether. Alcohol and solvent ether plays the role of the vehicle, pyroxillon as film producing agent and castor oil gives flexibility. Liniment Liniments are liquid or semi liquid preparations meant for external applications to the skin. They are usually applied by rubbing or friction but should not be applied on broken skin. Containers of such formulations should be flutted bottles bearing the label instruction “for external use only” and “shake the bottle” Gargles These are aqueous solutions used for the prevention and treatment of throat infections. The preparations are usually concentrated solution which need to be diluted with water before further use. Gargles exhibit their activity through close or intimate contact with the throat for a period of time after which they are spewed out of the mouth. They are mostly not to be swallowed although sometimes accidental swallowing may occur. When aspirin gargles are used, they can be swallowed after use. Mouth washes Mouthwashes are usually aqueous solutions in concentrated form with a pleasant taste and flavor used for rinsing, deodorant, refreshing or antiseptic action. Medicated mouthwashes may contain astringents, antibacterial agents, protein precipitants or other agents. They are generally used after dilution with warm water on the mucuous membrane of the mouth. Examples are compound sodium chloride mouthwash and zinc chlorides mouthwash. Lotions Lotions can be described as liquid suspensions or dispersions meant for application to the skin. They are strictly for external use and should be rubbed into the skin without friction. They are composed of alcohol and glycerin. While alcohol plays the role of aiding a quick drying of the skin, which leaves a cooling effect, glycerin moistens the skin and its effect can be felt for a long time. Eye drops These are sterile aqueous or oily solutions or suspensions meant for instillation into the eyes. Eye drops must compulsorily be sterile, isotonic, buffered and free from foreign particles which may cause irritation to the eyes when they are used. They could be applied directly to the corneal surface or to the space between the eye ball and eye lids. Substances incorporated into eye drops for medicinal uses include antiseptics, anaesthetics, anti—inflammatory agents, mydriatric or miotic properties. Containers for dispensing eye drops must be glass or suitable plastics with a screw cap fitted with a rubber teat or a glass dropper to assist in delivering the drug into the eye. Nasal and ear drops Nasal drops are usually aqueous solutions intended for instillation into the nostrils or ear by means of a dropper. They are often medicated solutions or dispersions. They are commonly used for their antiseptic, local analgesic or vasoconstrictor properties. Examples are ephedrine nasal drops, gentamycin eye and ear drops. Inhalations Inhalations are liquid preparations containing volatile ingredients. They are usually used to relieve nasal congestion and inflammation of the respiratory airways. They may be applied as a pad, or added to hot water and vapours are inhaled for some short period of time ( 5-10 min). Examples are benzoin, eucalyptus, and menthol inhalations. Paints Paints are liquid preparations meant for external use on the skin or mucous membrane. They are generally made up of volatile solvents which evaporates rapidly leaving a dry film of the medicament. Paints used on the throat are called throat paints and they are viscous preparation. They are constituted mostly of high percentages of glycerin which enables the preparations to stick on surfaces. Examples include compound benzoic acid ointment, calamine ointment, emulsifying ointment etc.
