1. introduction, route of administration

IntroductIon to
Pharmacology
Dr.Arul Amuthan
Lecturer in Pharmacology
Melaka Manipal Medical College
Manipal University 1

 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 drugs
2

What is drug ?
 Substance that modify the physiological systems or
pathological state for the benefit of the recipient.
3

 Pharmacokinetics:
What the body does to the drug
 Absorption, Distribution, Metabolism, Excretion
[ADME]
4

 Pharmacodynamics:
What the drug does to the body
 Drug’s mechanism of action
 Pharmacological effects of drug
 Adverse effects of drugs
 Drug interaction
5

6
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
8

 Plants:
Morphine, codeine, atropine, quinine, digoxin
 Animals: insulin, thyroxine
 Microorganisms: penicillin, streptomycin
 Minerals: iron, calcium, zinc
I. Natural sources:
9

II Semisynthetic sources:
Ampicillin, Amoxicillin (semisynthetic penicillins)
Diacetyl morphine
III.Synthetic sources:
 paracetamol, erythromycin, pethidine
10

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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)
12

2.Generic name:
Assigned by - United States Adopted Name (USAN) council
British Approved Name (BAN) council
Used uniformly in all countries
After the drugincludedin pharmacopeia - official name
 Aspirin, paracetamol
13

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)
14

Sources of drug information
Pharmacopeia:
 Book containing names of officially approved drugs
with their physical and chemical characteristics.
 Eg: Indian Pharmacopoeia (IP)
 BP, USP
15

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, ibuprofen
18

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
19

Advantages:
Unpleasant drugs
In vomiting, unconscious cases
Disadvantages:
Inconvenient, embarrassing
Causes rectal inflammation
Prednisolone for ulcerative colitis
Ergotamine, diazepam for systemic effect
20
Enema (fluid)
suppositories (tablets)
Rectal:

Intradermal:
Disadvantages:
Painful, no self administration
small amount of drug is administered
Eg: BCG vaccine, drug sensitivity tests
22

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
23

Intramuscular:
Advantages:
Rapid absorption
Depot injections
10 ml can be given at a time
Useful in vomiting, diarrhea, unconscious patients
Bypass first pass metabolism
Disadvantages:
Sterilization required
Painful, no self administration
Injury 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
26

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, oestrogen
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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, halothane
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Drug into subarachnoid space - Intrathecal
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 Intrathecal – lignocaine, amphotericin
 Intra articular – hydrocortisone

1. introduction, route of administration

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