Drug Antagonism Definition in Pharmacology

What is drug antagonism definition in pharmacology? What is antagonism drug interaction?

drug antagonism definition in pharmacology - antagonism drug interaction example

Drug antagonism definition in pharmacology

Antagonism of drugs – What it drug antagonism mean in pharmacy? The definition of drug antagonism is a drug that lowers or blocks the effect of a neurotransmitter.

Antagonism is when one drug’s effect is blocked (or slowed down) by another drug. In other words, when two or more drugs that have opposite effects on the body work together. As a result, one or more drugs may not work as well or work less well when interacting.

Antagonist drug definition

Drugs that reduce or inhibit the activity of another drug or an endogenous molecule are referred to as drug antagonists.

Types of Antagonism

Four types of drug antagonism are:

Physical antagonism

When a drug physically inhibits the effect of another drug.

Chemical antagonism

In this case, a chemical interaction between two or more drugs occurs inside the body, which blocks or reduces biological activity.

Physiological / functional antagonism

This occurs when two drugs, one drug and one endogenous chemical, act on two separate receptors to cause physiological reactions at odds with one another.

For example, histamine and adrenaline. Histamine causes bronchoconstriction and vasodilation by acting on its receptors. Adrenaline counteracts the effects of histamine by acting on its own receptors to generate bronchodilation and vasoconstriction.

Pharmacological antagonism

This is an antagonism caused by receptor blocking. The antagonist prevents the agonist from attaching to its receptor, while it attaches to the receptor but has no effect.

Drug antagonism example

  • Physiologic: Alcohol + Caffeine
  • Biochemical: Phenobarbital + Cimetidine
  • Chemical: Cholestyramine + Dicumarol
  • Pharmacological : Acetylcholine + Atropine

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