Mechanisms of drug effect

Vivian Imbriotis | Jan. 5, 2026

Drugs can exert an effect on the body by four mechanisms:

  1. Acting physically or chemically on the body gasses or fluids
  2. Acting by agonizing, antagonizing, partially agonizing, or modulating receptors (ion channels, GPCRs, nuclear receptors)
  3. Inhibiting enzymes
  4. Binding to a foreign substance

Osmotic: mannitol

Density: heliox

Acid-base: sodium bicarbonate

Redox: methylene blue, nitrates (in cyanide poisoning)

Chelation: Vitamin B12 (cyanide chelation)

Blockade: lignocaine

Allosteric modulation: Benzodiazepines bind to and increase flux throug GABAa receptors

GPCRs that increase adenylate cyclase: beta-1 agonists

GPCRs that increase IP3 and DAG: alpha-1 receptor agonists

Cystosol receptors: glucocorticoids

Nuclear receptors: thyroid hormone

Intracellular: milrinone

Extracellular: neostigmine

Binding other drugs: sugammadex

Binding toxins: sodium thiosulfate