Enzyme mediated drug action
ENZYME MEDIATED DRUG ACTION
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Rate of reaction increases
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Enzyme induction – microsomal induction by drugs – increased synthesis of proteins
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Enzyme inhibition – a most common mode of drug action
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Non specific – metal salts, acids, alkalis inhibit nonspecifically
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Specific - particular enzyme affected – either competitive or noncompetitive
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Competitive – competition with normal substrate
Equilibrating type
Non-equilibrating type
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React with the same site as that of substrate but form strong covalent bonds or have very high affinity than the normal substrate eg.. organophosphates form covalent bond with cholineesterase methotrexate - 50,000 times more affinity for the enzyme DHFR than DHFAcid
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Non-competitive - reacts with some other site and not on the catalytic site but alters the enzyme loss of catalytic property eg.. aspirin – Cyclooxygenase disulfiram – aldehyde dehydrogenase digoxin - Na+ K+ ATPase
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Last modified: Wednesday, 25 April 2012, 7:03 AM