Potency (pharmacology)

Potency (pharmacology) refers to the measure of drug activity expressed in terms of the amount required to produce an effect of given intensity. A highly potent drug evokes a given response at low concentrations, while a drug of lower potency evokes the same response only at higher concentrations. Higher potency does not necessarily mean more side effects.

Determination of Potency

Potency is determined by various factors including the affinity (the ability of the drug to bind to its target), efficacy (the relationship between receptor occupancy and the ability to initiate a response at the molecular, cellular, tissue or system level) and the concentration of the drug at the receptor site.

Factors Influencing Potency

The potency of a drug can be influenced by factors such as the route of administration, the time of administration, and the individual's age, weight, and health status. Other factors that can influence potency include drug interactions, tolerance, and the presence of certain diseases.

Potency vs Efficacy

While potency refers to the amount of drug needed to produce an effect, efficacy refers to the maximum effect that can be achieved by a drug, regardless of dose. A drug may be highly potent but have a low efficacy, meaning it produces a small effect even at its maximum dose.

Clinical Significance

Understanding the potency of drugs is crucial in clinical pharmacology as it allows for the comparison of different drugs and their doses. This is particularly important when switching from one drug to another, or when adjusting the dose of a drug.

See Also

• Pharmacodynamics
• Pharmacokinetics
• Dose-response relationship
• Therapeutic index