Science of drug which deals with interaction of exogenously administered chemical molecules with living system.


(What the drug does to the body)
Physiological and bio-chemical effect of drugʻand their mechanism of action at macro molecular or sub cellular or organ system level

Pharmacokinetics –

(What the body does to the drug)
Movement of the drụg and alteration of the drug by the body. It includes absorption, bio transformation and excretion of the drug

Drug –

(Drogue = dry herb)

A substance which can modify or explore the physiological system (pathological state for the benefits of recipient.

Pharmacotherapeutics –

Application of pharmacodynamic information together with knowledge of the diseases.

Clinical pharmacology –

Scientific study of the drug in man. It includes pharmacodynamics

Clinical pharmacology –

Scientific study of the drug in man.. It includes pharmacodynamics and pharmacokinetic investigation.

Chemotherapy –

Treatment of systemic infection/malignancy with specific drug that have selective toxicity for the organism or malignant cells with no or minimal effect on the host cells.

Absorption –

Movement of drug from its side of administration into the circulation.

Bio-availability :-

It is the fraction of administered dose of a drug that reaches the systemic circulation in the unchanged form.

Bio-transformation –

Chemical alteration of the drug in the body. .

First order kinetics –

– Rate of elimination § concentration
– clearance constant

Zero order kinetics

– Clearance §1/concentration
– Rate of elimination = constant

Plasma –

The plasma half life of a drug is the time taken for its plasma concentration to be reduced to half of its original value.

Plateau Principle –

When constant dose of A drug is repeated before the expiry of 4 tys. It should achieve the higher peak concentration.

Affinity –

Ability of the drug to combine with the receptor

Efficacy –

(Intrinsic Activity IA)

– Ability of the drug to activate the receptor.

Agonist –

Have both (Affinity and maximum efficacy or intrinsic activity) IA = 1

Partial Agonist

– Have Affinity and submaximal Intrinsic Activity. (IA = between 0 to 1 )

Inverse Agonist –

Have Affinity but no intrinsic activity/efficacy (IA =0) Agonist – When one drug increases the action of another drugs they are said

Competitive Agonist –

Have Affinity but intrinsic activity with a minus sign (1A = 0 to -1 )


When one drug increases the action of another drugs they are said agonist.

Antagonist –

When one drug decrease/inhibit the action of another, they are called Antagonist .

Synergism –

When the action of one drug is increased by the other, it called synergism
Types – (2)
Additive = Effect of drug A + B = Efect of drug A + Effect of drug
B Supra additive = Effect of drug A + B > Effect of drug A + Effect of drug B

Drug Action –

Combination of the drug with its receptors resulting in a conformational change.

Drug Effect :-

It is the ultimate change in biological function brought as a consequences of drug action

Drug Potency – Amount of drug needed to produce a certain action

Drug efficacy – The maximal response that can be elicited by the drug

Dose – Appropriate amount of drug needed to produce a certain degree of response in a patient.


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