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Mechanism of Benzodiazepines and
Barbiturates

GABA mediated chloride channel have
5 subunits two alpha, two beta and on
gamma subunit.

Benzodiazepines and newer
hypnotics (like zolpidem)

Binding at single site between alpha

and gamma subunits

 Benzodiazepines antagonist
Flumazenil also bind to this site

Barbiturates

Bind to sites on alpha and beta subunits

GABA

Bind to site between alpha and beta subunits

Tolerance

 Decrease responsiveness when used chronically in larger amount.

 Reduction in drug effect to amount of drug that was previously
effective

Cross tolerance

Cross tolerance occurs when a person is tolerant to effects of a Drugs and

he also develop tolerance to another drug

 This happens with two drugs with similar functions or effects for
example acting on same cell receptor

Contents

Pharmacology Mnemonics and Short Notes By Muhammad Ramzan Ul Rehman