Guided by,K.charhate sir

presented by,priyanka R Todkari

M-PHARM(Q.A.)

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1)INTRODUCTION.

2)FACTORS AFECTING BIOTRANSFORMATION OF DRUG.

- induction of drug metabolising

enzymes

- inhibition of drug metabolising

enzymes.

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Biotansformation is the chemical

modification made by organism on a

chemical compound.

The chemical conversion of one form to

another is called as biotransformation of

drug.

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The alteration of a substance within the

body as by action of enzymes is called

biotransformation.

The term is used synonymously with

metabolism.

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Physicochemical properties of drug.

Biological factors.

chemical factors.

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. 1) molecular size and shape, 2)pKa, 3)acidity/basicity, 4)steric and electronic characterestric of drug. 5)Stereochemical nature of drug.

& 6)Electronic characteristic of a drug

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1) Species differences. 2 ) Strain differences. 3) Sex differences. 4)Age. 5)Diet. .6)Altered Physiochemical Factors- a)Preganacy; b)Hormonal Imbalance; c)disease status. 7)Temporal Factors

a)circardian Rhythm; b) circannual Rhythm.

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1) Induction of drug metabolising

enzymes.

2) Inhibition of drug metabolising

enzymes

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The phenomenon of increased drug

metabolising ability of the enzymes by

several drugs and chemicals is called as

enzyme induction.

The agents which bring about such

effect are known as enzyme inducers.

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a)They are lipophilic compounds.

b) They are sustrate for the inducted

enzyme system.

c) They have long elimination half-lives.

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a)Increase in both liver size and liver blood flow. b)Increase in both total and microsomal

protein content. c) incresed stability of enzymes. d) incresed synthesis of cytochrome P-450. e) decrease degradation of cytochrome

P- 450. f) proliferation smooth endoplasmic reticulum.

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1)Phenobarbitol type inducer.

2)Polycyclic hydrocarbon type inducer.

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a)Decrease in pharmacological activity

of drug.

b)Increased activity where the

matebolitesare active.

c)Altered physiological status due to

enhanced metabolism of endogenous

compounds such as sex harmones.

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Inducer Drug with enhanced metabolism.

Barbiturates Coumarins,phenytoin,cortisol,oral

contraceptives.

Alchol Phenobarbital,coumarin

Phenytoin Cortisol,coumarin

Rifampicin Coumarin,tolbutamide

Cigarette Smoke Nicotine,amino azo dyes.

A decrease in the metabolisming ability of

an enzyme is called as enzymes

Inhibition.

It may be-

1)Direct Inhibition.

2) Indirect Inhibition.

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It can occurs by one of 3 mechanism.

a) Competitive Inhibition.

b) Non-Competitive Inhibition.

c) Product Inhibition.

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it is brought about by one of the two

mechanisms.

a) Repression.

b) Altered physiology.

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Enzymes Inhibition is more clinically than

enzyme induction.

Some examples of inhibitors and drug

affected by them ,

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Inhibitors Drugs with Decreased

Metabolism

MAO inhibitors Barbiturates,tyramine

Coumarin Phenytoin

Allupurinol 6-Mercaptopurine

PAS Phenytoin,hexobarbitol.

1)D.M.BRAMHANKAR; SUNIL

B.JAISWAL

Page no.140

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