sources and dosage forms of drugs
TRANSCRIPT
General Introduction to Pharmacology
By Dr. Sameh Abdel-Ghany
Pharmacology Definition
It is science dealing with drugs.
Drug:
a chemical agent that stimulates or inhibits an existing cell function but not create new one
Drug Sources
Biosynthetic
Synthetic
Natural sources
Semisynthetic
Natural Sources
Text
Plants
Animals
Microbiological
Natural SourcesMinerals
A- Plant SourcesExamples:
Rauwolfia serpentina
TobaccoPapavarum somniferum
Atropabelladonna
ReserpineNicotineMorphine Atropine
Examples
Digitalis lanataDigitalis Fox glove
Examplesginger oilزيت الزنجبيل
eucalyptus oil peppermint oilزيت النعناع
clove oilزيت القرنفل
Examples
cod liver oilزيت كبد الحوت
peanut oil السودانىزيت الفول
croton oilcastor oilزيت الخروع
olive oilالزيتونزيت
Examples
gum tragacanthGum acacia psyllium seeds gut agar
B-ANIMAL SOURCES :Examples
VaccinesInsulin
C-MICROBIOLOGICAL SOURCES
Many life-saving drugs are obtained from fungi, moulds and bacteria
e.g. penicillin from
Penicillium notatum
II. SEMISYNTHETIC SOURCES
used to prepare drugs when the synthesis of drugs (complex molecules) may be difficult, expensive and uneconomical or when the natural sources may yield impure compounds.
Some examples are semisynthetic human insulin.
III. Synthetic
At present majority of drugs used in clinical practice are prepared synthetically
e.g as aspirin, oral antidiabetics, antihistamines, amphetamine, chloroquine, chlorpromazine and thiazide diuretics.
IV. BIOSYNTHETIC SOURCES
New field which is being developed by mixing discoveries from molecular biology, recombinant DNA technology, DNA alteration, gene splicing, immunology and immunopharmacology.
Examples
Human insulinHepatitis-B vaccine
Uses of drugs
I. Treatment of diseases
II.Prevention of diseases (Prophylactic)
III.Diagnostic
IV.Prevention of normal biological function
Processes involved in drug therapy:
1. Pharmaceutical
Active ingredient obtained from any source should be put in proper dosage forms to be absorbed
Processes involved in drug therapy:
2. Pharmacokinetics
It is the action of body toward drug given
It consist of 4 precesses:absorptiob –distribution – metabolism and excretion (ADME)
Processes involved in drug therapy:
3. Pharmacodynamics
It is the effect of drug on body
It includes mechanism of action
Processes involved in drug therapy:
4. Pharmacotherpeutic
It deals with use of drug diagnosis , prevention and treatment
Dosage Forms
Divisions of Dosage forms
Liquid
Solid
Semisolid
Divisions
of dosage
forms
I. Liquid Forms
Aqueous preparations Alcoholic preparations
1.Solutions 2.Syrups 3.Emulsions 4.Suspension5.Infusions6.Decoction 7.Lotion
1.Elixirs2.Spirits (Essences)3.Tinctures
1. Aqueous preparations
I. Solutions :
are homogeneous mixtures of one or more solutes dispersed in a dissolving medium (solvent).
II.Syrups:
are aqueous solutions containing:
a sugar or sugar substitute ±flavoring agents
III. Suspensions
are mixtures of small water insoluble solid drug particles dispersed in water using suspending agent e.g. gums.
IV. Emulsions
are milky solutions with bitter taste and odour.
It is intimate mixture of two immiscible liquids.
V. Decoction : obtained by boiling in water dried plants.
VI.Infusion: obtained by soaking dried plants in cold or boiling water. like decoctions, they spoil quickly
2. Alcoholic preparations:
I. Elixirs:
sweetened and flavoured hydroalcoholic solutions that contain varying amounts of alcohol.
may be non-medicated to be used only as vehicles (e.g. bitter orange elixir) or medicated when they include specific drug (e.g. barbital elixir).
Example
II.Spirits (Essences):
volatile oils dissolved in alcohol
e.g. peppermint spirit, and lemon spirit.
III.Tinctures:
alcoholic solutions of non-volatile substances (vegetables).
e.g. tincture belladonna
II. Solid Forms
Tablets
Capsules
Powder
Solid
forms
A. Tablets
1)Tablets that are swallowed whole
2)Effervescent tablets
3)Chewable tablets
4)Buccal and sublingual tablets
5)Controlled-release tablets
6)Lozenges
B. Capsules
1)Hard gelatin capsules
2)Soft gelatin capsules
3)Controlled-release capsules
C. Powders
may be dispensed in small paper packets or in bulk.
Cont.
It may be formulated in the form of effervescent granules
III. Simisolid Forms
Suppositories
Ointments
Creams
Liniments
Gel
a- Ointment
b- Cream
c- Liniment
d- Gel
e- Suppositories
IV. Inserts, Implants, and Devices
used to control drug delivery for localized or systemic drug effects.
Device e.g artificial pancreas
Implant e.g Norplant
V. Transdermal Patches
deliver drugs directly through the skin and into the bloodstream.
Example Nitroglycerin patches and nicotine patches
VI. Targeted Drug Delivery Systems
A) Macromolecular
carrier systems
TDDS
B) Particulate drug
Delivery systems
1- Liposomes:
2- Microencapsulation .
A) Macromolecular carrier systems
drug can be attached to the polymer chain either directly or via a spacer.
Attachment of polyethylene glycol (PEG) to proteins can protect them from rapid hydrolysis or degradation within the body, and increase blood circulation time and lower the immunogenicity of proteins
e.g. PEGylated forms of interferons
B) Particulate drug Delivery systems
I. Liposomes:
Water-soluble drugs can be entrapped in liposomes by intercalation in the aqueous bilayers, while lipid-soluble drugs can be entrapped within the hydrocarbon interiors of the lipid bilayers.
e.g amphotericin B formulated in liposomes .
II.Microencapsulation
is a technique that involves the encapsulation of small particles or solution of drugs in a polymer film or coat.
e.g. Lupron Deopt