GENERAL
PHARMACOLOGY
DR. S. K. AMPONSAH
PHARMACOLOGY
• Pharmacology is the science of how drugs interact with
biological systems.
• It is a science that is basic not only to medicine but also
to pharmacy, nursing, dentistry, and veterinary
medicine.
• Pharmacology ranges from examining the effects of
chemical agents on subcellular mechanisms, to
treatment and prevention of major diseases.
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Pharmacology
• Pharmacology unlocks the mysteries of drug actions,
and also involves discovery of new therapies.
• Currently, novel pharmacological areas include genomic
approaches to treatment.
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Pharmacology
• Two important and
pharmacology
are
pharmacodynamics.
interrelated areas
pharmacokinetics
• Pharmacokinetics deals with the
distribution, and elimination of drugs.
under
and
absorption,
• Pharmacodynamics is the study of the molecular,
biochemical, and physiological effects of drugs on
cellular systems.
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Sub-divisions of pharmacology
• Pharmacology can be sub-divided into;
 Neuropharmacology
 Cardiovascular pharmacology
 Endocrine pharmacology
 Clinical pharmacology
 Toxicology
 Pharmacogenetics
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Neuropharmacology
• This is the study of drugs on components of the
nervous system, including the brain, spinal cord, and
the nerves that communicate with body.
• Neuropharmacologists are concerned with drugs used
in the treatment of disease states of the nervous
system.
• They also use drugs as tools to elucidate basic
mechanisms of neural function.
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Cardiovascular pharmacology
• This studies the effects of drugs on the heart and the
vascular system.
• Cardiovascular pharmacologists study the effects of
drugs on arterial pressure and blood flow in specific
vascular beds.
• They also study physiological mediators and neural
activity associated with the cardiovascular system.
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Endocrine pharmacology
• This is the study of the effect of drugs that are either
hormones or hormone derivatives on the body.
• It is also the study of drugs that may modify the
actions of hormones secreted by the body.
• Endocrine pharmacologists are involved
controlling diseases of endocrine origin.
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Clinical pharmacology
• This is the application of pharmacological principles
and methods in the real world (patients).
• Clinical pharmacologists study how drugs work, and
how their effects can alter disease in humans.
• In the clinical setting they work directly with patients,
participate in experimental studies, clinical trials,
investigate drug interactions and adverse reactions.
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Toxicology
• It is the study of the toxic effects of drugs and other
chemicals.
• In the context of pharmacology, toxicology involves
studying the adverse effects of drugs on organ systems
and cellular processes.
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Pharmaco-genetics/genomics
• It is the study of how a person’s genetic makeup
affects response to drugs.
• Response to a drug could vary from little or no effect,
to exaggerated adverse drug reactions.
• Drug treatment can then be tailored to each patient
using the individual’s pharmacogenetic data.
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PHARMACOLOGY:
PAST AND PRESENT
• Distinctions between the efficacy and toxicity of drugs
were recognized thousands of years ago.
• As humans took plants, animals and minerals as food,
they noted both therapeutic and toxic effects.
• Ancient Chinese writings and Egyptian medical papyri
represent the earliest compilations of pharmacological
knowledge.
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Egyptian medical papyri
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Past
• These old writings included rough classifications of
diseases and recommendations for treatment.
• The 17th century saw an increase in experimentation of
crude drug preparations for their therapeutic effects.
• These experiments were conducted to get ideas about
the possible toxic doses of certain agents such as
cinchona bark (quinine) and coca leaves (cocaine).
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Past
• By the 18th century, many such investigations into
crude drug preparations were being conducted.
• The birth of experimental pharmacology is generally
associated with the work of the French physiologist
Francois Magendie in the early 19th century.
• Magendie’s research on strychnine-containing plants
clearly established their site of action as being the
spinal cord.
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Francois Magendie
(6 October 1783 – 7 October 1855)
An 1809 painting depicting strychnine
poisoning
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Past
• Magendie provided evidence that drugs and poisons
must be absorbed into the bloodstream and carried to
the site of action before producing effects.
• The work of Magendie and Claude Bernard (Magendie’s
student), on curare-induced muscle relaxation and
carbon monoxide poisoning also helped to establish
some principles of pharmacology.
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Claude Bernard
(12 July 1813 – 10 February 1878)
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Past
• During the second half of the 19th century, it was in
the German-speaking universities that pharmacology
really began to emerge as a well defined discipline.
• This process began with the appointment of Rudolf
Buchheim as teacher of material medica at the
University of Dorpat in Estonia.
• Materia medica was concerned with the origin,
constituents, and preparation of traditional agents used
in healing.
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Rudolf Buchheim
(1 March 1820 – 25 December 1879)
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Past and present
• Buchheim called for an independent experimental
science of pharmacology, involving the study of the
physiological action of drugs.
• He established the first Institute of Pharmacology at
the University of Dorpat in 1847.
• Among the students who received research training in
Buchheim’s laboratory was Oswald Schmiedeberg
(Father of Modern Pharmacology).
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Oswald Schmiedeberg
(10 October 1838 – 12 July 1921)
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Past
• In 1872, Schmiedeberg became professor
pharmacology at University of Strasbourg, France.
of
• One very good student of Schmiedeberg, John Jacob
Abel, brought the science of experimental
pharmacology to the USA.
• In 1891, John Jacob Abel founded the first Department
of Pharmacology in the United States at the University
of Michigan.
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John Jacob Abel
(19 May 1857 – 26 May 1938)
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Past
• In the beginning of the 20th century, Paul Ehrlich
(father of chemotherapy) conceived the idea of seeking
chemical agents to treat infections.
• His work on the concept of the “magic bullet”
treatment of infections paved way for the triumphs of
modern-day chemotherapy.
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Paul Ehrlich
(14 March 1854 – 20 August 1915)
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Past
• The contribution of 20th century pharmacology was
immense, with over 20 pharmacologists having received
Nobel prizes.
• Their contributions include discoveries of many
important drugs, neurotransmitters, and secondary
messengers.
• These pharmacologists also contributed to the
understanding of physiological and biochemical
processes.
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Present
• Pharmacology in the 21st century continues to build on
the discoveries of the previous century.
• Obtaining the sequence of the human genome has
allowed scientists to further understand variations in
drug response.
• Nanotechnology approach has also come to aid in the
delivery of drugs to specific targets.
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PHARMACY
• Often confused with pharmacology, pharmacy is a
separate discipline in the health sciences.
• Pharmacy is the art, practice or profession of
preparing, preserving, compounding and dispensing
medical drugs.
• It is a health science charged with ensuring safe and
effective
use
of
pharmaceutical
agents.
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DRUG AND DRUG PROPERTIES
• DRUG: A drug is any natural, semi-synthetic or
synthetic chemical substance used in the diagnosis,
prevention or treatment of disease or for other
medical reasons.
• Is food a drug? Any good examples?
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Sources of Drugs
1. Natural
•
•
•
•
These are obtained from plants, microbes, animal
tissues and minerals.
One major compound found in plants that has
pharmacological activity are alkaloids.
Example of alkaloids used as drugs include morphine,
cocaine, quinine and atropine.
The antimalarial agent artemisinin is from the plant
Artemisia annua.
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Natural
• Several antibiotics have also been isolated from
microorganisms
such
as
Penicillium
and
Streptomyces species.
• Hormones are the most common type of drugs
obtained from animals.
• Insulin used by diabetic patients are obtained from
pig and cattle (Porcine and Bovine insulin,
respectively).
• Minerals are also obtained from the earth or soil
(Iron and Potassium).
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Example
Drug Name
Classification
Magnesium
Milk of Magnesia
Antacid, Laxative
Zinc
Zinc Oxide Oint.
Sunscreen, Skin
protectant
Lithium
Lithium Carbonate
Antidepressant
Iron
Ferrous sulphate
Anti-anemic
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Natural
• Vitamins are also from natural substances ie plants.
• Your body needs these vitamins to grow, develop,
and function normally.
• A well-balanced diet usually provides all of the
vitamins required.
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Natural sources
• However, there are times, such as during pregnancy
and childhood, when your body needs more vitamins
than usual.
• Certain illnesses occur as a result of your body not
getting efficient amount of vitamins it needs e.g
night blindness, scurvy, and pellagra.
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2. Synthetic
• The rise of modern chemistry has enabled scientist
to synthesize new compounds.
• Aspirin and a procaine (local anesthetic) were
amongst the first to be synthesized in the lab.
• Scientist have developed new drugs based on
advances technology that model drug receptors.
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Synthetic
• This facilitates the design of drug structures that best
fit the 3D receptor conformation.
• Other examples of synthetic drugs include;
paracetamol and phenytoin (anticonvulsant).
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3. Semi-synthetic
• It is a chemical synthesis that uses compounds isolated
from natural sources (e.g. plants or bacterial or cell
cultures) as starting material.
• Semi-synthetic drugs are made if the natural molecule
is structurally complex or difficult to be produced by
total synthesis.
• The antimalarial drug artemether (a component of
Coartem) is a semisynthetic agent derived from
naturally occurring artemisinin.
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Semi-synthetic
• Most often semi-synthetic drugs are a modification
of naturally occurring ones.
• Their structure has other groups added to existing
natural occurring compounds.
• Other examples include heroine from morphine,
homatropine from atropine.
• Sometimes animal insulin are changed into human
insulin.
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DRUG NOMENCLATURE
• Drugs can be classified by one of these 3 names;
 Chemical: a long name that refers to the chemical
structure of the drug
 Generic: a shorter preferred name, derived from the
chemical name
 Trade/brand name: assigned by manufacturer of the
drug
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Drug nomenclature
Chemical name:
 Gives exact chemical composition of the drug
 Can also be the IUPAC name of the drug
Generic (non-proprietary) name:
 Typically derived from chemical name
 Usually shorter
 Given by the United States Adopted Names Council
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Drug nomenclature
Trade (proprietary) name
 This name is registered by the drug manufacturer.
 Followed by the trademark symbol ®.
 This name can only be used by the manufacturer.
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Examples
CHEMICAL NAME
GENERIC NAME
BRAND NAME
N-acetyl-p-aminophenol
Acetaminophen/Paracetamol
Tylenol, Panadol,
etc
7-chloro-1-methyl-5-phenyl-3H1,4-benzodiazepin-2[1H]-one
Diazepam
Valium
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DRUG PREPARATIONS/FORMULATIONS
• Drugs are seldom administered in pure form.
• They are made into various dosage forms to facilitate
administration and ensure safety and efficacy.
• A dosage form is a system or device by which the drug
is delivered to the body.
• In a dosage form, the active ingredient is combined
with inert ingredients that facilitate administration of
the drug.
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Drug formulation
• Dosage forms often have;
 Excipients—Excipients are inactive substances used as carrier for
the active ingredient.
 Binders—Binders promote adhesion of active and inactive
ingredients in tablets.
 Diluents—Diluents are additives used to increase the bulk weight
or volume of a dosage form.
 Preservatives—Preservatives are substances that prevent or
minimize the growth of bacteria or other microorganisms.
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Drugs formulation
• Drugs can be prepared as;
 Solid dosage forms
 Semi-solid dosage forms
 Liquid dosage forms
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SOLID DOSAGE FORM
• Solid dosage forms include tablets, caplets, capsules,
lozenges, granules and powders.
• Solid dosage forms offer a number of advantages
which include:
 Good stability
 Ease of packaging
 Ease of dispensing
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Solid dosage form
• Solid dosage forms also allow for accurate dosing.
• The entire dose is contained within the contents of the
solid dosage form, which minimizes measuring errors.
• Solid dosage forms may, however, be difficult to
swallow, have a slow onset of action, and may be
degraded by the acidic contents in the stomach.
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1. Tablet/caplet
• Tablets are available in variety of sizes, shapes, colors,
and thicknesses.
• They are produced by compression, and are composed
of one or more active ingredients and one or more inert
substances.
• Some pharmaceutical manufacturers produce a hybrid
of tablet and capsule called caplets.
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Caplets
• Caplets are shaped like
capsules.
• They are often easier to
swallow than large
tablets, and are more
stable than capsules.
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Tablets
• Tablets can be scored so they may be easily broken in
halves or quarters.
• Some are also designed to be chewed (chewable
tablets) and often contain a base that is flavored or
colored.
• Tablets can be formulated with delayed release
characteristics to allow for less-frequent dosing
and/or side effects.
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Tablets
• Some tablets may have a coating
(enteric coated) applied to the
outside to mask unpleasant flavor
or odor.
• They are also meant to protect
the drug from stomach acid or to
protect the stomach lining from
the drug.
• Enteric coated tablets should not
be chewed or crushed.
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Tablets
• Some tablets are also film-coated.
• They are coated with a thin outer layer
of water-soluble material that
dissolves rapidly in the stomach.
• The coating is designed to mask the
unpleasant taste or odor of the
medication.
• Coating also protects drugs from
deterioration due to air and light.
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2. Capsules
• Capsules are a solid dosage form in
which the drug is enclosed within a
hard or soft gelatin shell.
• The gelatin shell dissolves in the
stomach, releasing the drug.
• The gelatin shell may be
transparent, semitransparent, or
opaque.
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Capsules
• A capsule may contain powders, granules or liquids with
one or more active ingredients and one or more inert
ingredients.
• Capsules can be formulated with delayed-release
characteristics to allow for less-frequent dosing and/or
side effects.
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Formulation designed to alter rate
• Tablets and capsules can be designed into immediaterelease formulations which release drug within a short
period of time after administration.
• Drugs can also be designed in delayed-release
formulations, which extend the duration of action.
• A delayed-release formulation may be enteric coated,
thus delaying the release of the medication until the
formulation has passed through the stomach.
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Formulation designed to alter rate
• A tablet or capsule must disintegrate after it is
ingested and dissolve in GIT fluids.
• Delayed-release formulations have an extended rate
of disintegration of drug in the GIT over several
hours.
• Thus, delaying the rate of absorption of drug into
circulation.
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3. Lozenges
• Lozenges, also known as troches or pastilles, are hard,
oval, or discoid solid dosage forms with a flavored
sugar base.
• They are dissolved in the mouth and generally have
local therapeutic effects.
• Over-the-counter lozenges for relief of sore throat are
a common example of this dosage form.
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4. Powders and granules
• Powders are finely ground dry
drugs that can be used topically
(athlete’s foot) or administered
orally.
• Granules are larger than powders,
and generally more stable than
powders.
Drug granules
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5. Suppositories
• A suppository is designed to be
inserted into the rectum (rectal
suppository) or vagina (vaginal
suppository)
• The suppository base is an
inactive ingredient, which melts
or dissolves in the body cavity,
releasing the medication.
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Suppository
• Some suppositories are designed for local action, while
others are used as vehicles for systemic drugs
(analgesics).
• Suppositories are often used in children and in adults
who are unable to take oral medications.
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SEMI-SOLID DOSAGE FORM
• Semisolid agents are different in their composition from
liquids or solids.
• They are usually intended for topical application.
• They may be applied to the skin, placed on mucous
membranes, or used in the nasal, rectal, or vaginal
cavity.
• Examples include creams, lotions, gels and pastes.
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1. Creams
• A cream is an example of an oil-in-water (O/W)
emulsion, because it contains a small amount of oil
dispersed in water.
• They are mostly intended for external use.
• Creams can be easily massaged into the skin, without
leaving an oily residue.
• Creams can also be formulated for vaginal or rectal
use.
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2. Lotions
• A lotion is an O/W emulsion that is thinner than a
cream.
• Lotions often contain more water than creams.
• Lotions penetrate into the skin and can cover large
areas without leaving an oily residue.
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3. Gels
• A gel contains solid medication particles, like a
suspension, in a thick liquid.
• It can be used internally and externally.
• The particles in a gel are ultrafine and are linked to form
a semisolid material.
• Gels can penetrate the skin without leaving a residue.
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4. Paste
• A paste contains more solid material and less liquid
base.
• Pastes are stiffer, less greasy, and applied more thickly.
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LIQUID DOSAGE FORM
• Solutions and suspensions are the most common
liquid formulations.
• They can be administered by oral, parenteral
(injectable) or other routes of administration.
• They provide a convenient means of administering
drugs to pediatrics and other patients who cannot
swallow solid forms.
• Less convenient because liquid would have to be
measured anytime dose is to be given.
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Solutions and suspensions
• Solutions and suspensions for oral administration are
often sweetened and flavored to increase
palatability.
• Sweetened aqueous solutions are called syrups.
• Sweetened aqueous-alcoholic solutions are known as
elixirs.
• The alcohol in elixirs are added when the drug is not
sufficiently water-soluble.
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Solutions and suspensions
• Sterile solutions and suspensions are available for
parenteral administration (injections).
• They come with a needle and syringe or with an
intravenous (IV) device.
• Some are also formulated into sterile powders with
sterile liquids that have to be mixed before injected.
• This is because the drug is not stable for long in
solution.
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Injectable drug solutions
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IV infusions
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Solutions and suspensions
• There are also sterile ophthalmic solutions and
suspensions.
• They are made with a dropper which is to be instilled
into the conjuctival sac.
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Ophthalmic solution
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OTHER DOSAGE FORMS
• Skin patches are drug preparations that allow the
drug to be slowly released from a patch for
absorption through skin.
• Once it crosses skin membranes it moves into
circulation or blood stream.
• They are used for drugs effective at a relatively low
doses.
• They are also very lipid soluble which aids them to
penetrate skin and diffuse into blood.
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Skin patch
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Aerosols
• These are drug preparations administered by
inhalation through the nose or mouth.
• They are particularly useful for treating respiratory
disorders.
• They are used because they deliver the drug directly
to the lungs.
• They also reduce the risk of systematic side effects.
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Aerosols
• A typical example of an aerosol is an inhalant.
• Nasal sprays also deliver drugs to have localized
effect in the nasal mucosa.
• Drugs can also be absorbed across nasal mucosa into
blood stream.
• For example, some nasal sprays can have analgesic
effects ie to treat pain.
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Aerosol
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