1. introduction, route of administration

Introduction to Pharmacology

Dr.Arul AmuthanLecturer in Pharmacology

Melaka Manipal Medical College Manipal University

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pharmacology - drug study

What is Pharmacology ?

Science that deals with the effects of drugs on living

system.

Sources, biological effects, therapeutic uses,

adverse effects and interactions of drugs2

What is drug ?

Substance that modify the physiological systems or

pathological state for the benefit of the recipient.

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Pharmacokinetics:

What the body does to the drug

Absorption, Distribution, Metabolism, Excretion

[ADME]

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Pharmacodynamics:

What the drug does to the body

Drug’s mechanism of action

Pharmacological effects of drug

Adverse effects of drugs

Drug interaction

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Pharmacotherapeutics:

Application of pharmacological information together

with disease knowledge for prevention and cure

Selection of drug, dose, duration of treatment

Toxicology:

Harmful effects of drug

Detection, prevention, treatment of poisoning

Study of adverse effects

Clinical pharmacology:

Scientific study of drugs in man

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P.kinetic/dynamic investigation in healthy and patients

Evaluation of efficacy and safety, adverse effects

Comparative trails, Surveillance

SOURCES OF DRUGS

I. Natural sources

II. Semisynthetic sources

III. Synthetic sources

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Plants:

Morphine, codeine, atropine, quinine, digoxin

Animals: insulin, thyroxine

Microorganisms: penicillin, streptomycin

Minerals: iron, calcium, zinc

I. Natural sources:

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II Semisynthetic sources:

Ampicillin, Amoxicillin (semisynthetic penicillins)

Diacetyl morphine

III.Synthetic sources:

paracetamol, erythromycin, pethidine

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Drug nomenclature:

Chemical name - Generic name - Trade name

3.Trade name: (brand, proprietary name)

Given by a pharmaceutical company

Sole property of the pharmaceutical company

A drug may have many proprietary names

Same company – different name in different countries

Prescription, over-the-counter drugs

Ecospirin, Disprin (for aspirin)

Crocin, Calpal (for paracetamol)12

2.Generic name:

Assigned by - United States Adopted Name (USAN) council

British Approved Name (BAN) council

Used uniformly in all countries

After the drug included in pharmacopeia - official name

Aspirin, paracetamol

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1. Chemical name:

Is the name of chemical compound present in a drug

Acetyl salicylic acid, Acetaminophen

Not suitable for prescribing

Number is given before name is framed (Eg: INR00439)

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Sources of drug information

Pharmacopeia:

Book containing names of officially approved drugs

with their physical and chemical characteristics.

Eg: Indian Pharmacopoeia (IP)

BP, USP

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Non-official references:

Physicians’ Drug Reference (PDR)

Dental Drug Reference (Mosby)

Monthly Index of Medical Specialists (MIMS)

Medical journals:

The Malaysian Journal of Medical Sciences

Medical Journal of Malaysia, BMJ

US Food and Drug Administration (FDA): www.fda.gov16

1. Enteral route: oral, sublingual, rectal routes

2. Parenteral routes: intradermal, subcutaneous,

intramuscular, intravenous, intra-arterial, intrathecal

3. Topical: skin and mucous membrane

4. Others: transdermal, inhalational

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Route of drug administration

Oral route: Advantages:

Safe, convenient for long use

Painless, self administered

Disadvantages:

Slow onset of action (not used in emergency)

Not suitable - in diarrhoea/vomiting/unconscious cases

- unpalatable/irritant drugs, unabsorbed drug

Aspirin, paracetamol, ibuprofen18

Sublingual: Advantages:

Quick onset of action, bypass first pass metabolism

Self administered, terminated by spiting out

Disadvantages:

In children

Bad smell & lipid insoluble drugs

Nitroglycerin for angina

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Advantages:

Unpleasant drugs

In vomiting, unconscious cases

Disadvantages:

Inconvenient, embarrassing

Causes rectal inflammation

Prednisolone for ulcerative colitis

Ergotamine, diazepam for systemic effect20

Enema (fluid)

suppositories (tablets)

Rectal:

Parenteral routes & site:

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Intradermal:

Disadvantages:

Painful, no self administration

small amount of drug is administered

Eg: BCG vaccine, drug sensitivity tests

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Subcutaneous:

Advantages:

Self administration is possible

Depot can be inserted into sc

Disadvantages:

Slow absorption, not useful in emergency

Suitable only for non-irritant drugs

Eg: Insulin, adrenaline

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Intramuscular: Advantages:Rapid absorptionDepot injections10 ml can be given at a timeUseful in vomiting, diarrhea, unconscious patientsBypass first pass metabolism

Disadvantages:Sterilization requiredPainful, no self administrationInjury to nerve, cause abscess

Eg: gentamicin, streptomycin, kanamycin 24

Intravenous: Advantages:

Directly reaches blood

Bypass first pass metabolism, 100% bioavailability

Emergency – fast onset of action

Large volume infused – iv fluids

High irritant drugs is given

Useful in vomiting, diarrhea, unconscious patients

Eg: furosemide, diazepam

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Intravenous: Disadvantages:

Once administered, can’t be stopped

Painful, no self medication

Strict aseptic precautions

Extravasation causes tissue necrosis

Causes thrombophlebitis

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Topical: (skin and mucous membrane)

Advantages:

More convenient, encouraging to patient

Efficiently delivered to local lesion areas

Disadvantages:

Local irritation, dermatitis

silver sulfadiazine ointment, diclofenac gel

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Transdermal/Transcutaneous:

Adhesive patch

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Advantages:

Self administered, better patient compliance

Prolonged duration of action

Less systemic side effect

Disadvantages:

Expensive

Local irritation causes dermatitis, itching

Patch may fall off unnoticed

scopolamine, nitroglycerine, oestrogen29

Inhalational:

Volatile liquids and gases are given for systemic effects

Advantages:

Absorption through alveoli, rapid onset of action

Less dose is enough, so less systemic toxicity

Amount of drug can be regulated

Disadvantages:

Irritation causes bronchospasm and high secretion

General anaesthetics – nitrous oxide, ether, halothane30

Drug into subarachnoid space - Intrathecal

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Intrathecal – lignocaine, amphotericin

Intra articular – hydrocortisone

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