Isosorbide 5-mononitrate differs from other clinically used organic nitrate vasodilators because of its almost complete oral absorption, the low intersubject variability in its plasma concentrations and pharmacokinetic parameters, its relatively long half-life and its lack of active metabolites. The drug does not appear to be bound to plasma proteins and it is metabolized primarily by denitration and conjugation. Its clearance is 127 ml/min, volume of distribution 48.5 litres and half-life 4.4 h. Its pharmacokinetics are linear over the dosage range likely to be used clinically. Sustained-release formulations of the drug could prove suitable for once-a-day administration. In disease states (cardiac, renal or hepatic), the plasma concentrations and pharmacokinetics of the drug appear to be similar to those in healthy subjects.