Sources and dosage forms of drugs

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