lowerpotency

Lowerpotency is a term used in pharmacology to describe a compound that produces a given biological effect only at a higher concentration or dose than a reference drug. Potency is typically read from dose–response curves, with higher EC50 or ED50 values indicating lower potency. It is important to distinguish potency from efficacy: a lower-potency drug can achieve a maximal effect similar to a higher-potency drug, but requires more of the substance; a high-potency drug may have a lower maximal effect (lower efficacy) in some contexts.

Measuring potency involves comparing dose-response relationships within the same assay or organism. Common metrics include EC50 (the concentration for 50% of the maximal response) and ED50 (the dose for 50% of the maximal response). Binding affinity, often expressed as Ki, also informs potency. In vivo potency is influenced by pharmacokinetic factors such as absorption, distribution, metabolism, and excretion, as well as pharmacodynamic factors like receptor affinity and intrinsic activity.

Factors that lower potency include reduced receptor affinity, rapid metabolic breakdown, poor oral bioavailability, and limited tissue distribution. Conversely, improved receptor interaction, favorable pharmacokinetics, or targeted delivery can raise potency.

Examples illustrate the concept: codeine has lower potency than morphine at the mu-opioid receptor and is a prodrug requiring metabolism to morphine for activity; caffeine exhibits relatively low potency at adenosine receptors compared with other stimulants. Understanding potency aids in dosing decisions, safety assessments, and drug development, where the balance between potency, efficacy, and therapeutic window is key.