The absorption, distribution, metabolism, and excretion of miglitol ((2R,3R,4R,5S)-1-(2-hydroxyethyl)-2-(hydroxymethyl)-3,4,5-piperidinet riol, CAS 72432-03-2, BAY m 1099) have been studied following single and repeated administration of non-labelled and radiolabelled (3H, 14C) drug to rats, dogs, and human volunteers via different routes of administration (intravenous, oral, intraduodenal) and at various doses (0.3-450 mg/kg). After intravenous administration, miglitol is excreted rapidly and completely via the renal route. No indication was found for a metabolization of radiolabelled miglitol. The (renal) clearance of miglitol is in the range of the glomerular filtration rate. Miglitol is rapidly eliminated from plasma with apparent elimination half-lives of 0.4-1.8 h. Miglitol is virtually not bound to plasma proteins. After oral administration miglitol is rapidly and at low doses also completely absorbed. At higher doses (> or = 5 mg/kg in rats and dogs, > 50 mg in humans) a saturation of absorption becomes evident. Miglitol is distributed predominantly in the extracellular space. The volumes of distribution are low (0.3-0.8 l/ kg). In rats high concentrations were initially found in the kidneys, the blood and some well-perfused tissues. The permeation across the blood/brain barrier is very low. Elimination from organs and tissues occurs rapidly resulting in very low residual radioactivity in the body 2 days after dosing (< 0.9% of the dose). At this very low concentration level a terminal elimination phase of radioactivity characterized by half-lives of 50-110 h was observed giving rise to a slight tendency for accumulation (accumulation factors < 6) following repeated administration to rats. In pregnant rats [14C]miglitol crossed the placental barrier slowly and to a limited extent. In lactating rats miglitol was found in milk in concentrations similar to those in the maternal plasma.