1 Ten healthy volunteers and 26 hospital in-patients with endogenous creatinine clearances of 98 to 4 ml min-' received an oral dose of 800 mg sulotroban (BM 13.177). The plasma and urine concentrations of sulotroban were measured by gas-chromatography over 72 h and the pharmacokinetic parameters were calculated. 2 The AUC rose from 28.5 mg 1-1 h in healthy volunteers to 631.4 mg 1-1 h in preterminal renal failure (medians). The CLR decreased from 317.0 ml min-' to 6.5 ml min'1 at the lowest renal capacity.3 According to the AUC values, reduction of the dose is not necessary at CLCr > 50 ml min-', a dose of 20-40% of normal is appropriate at CLCr of 20-50 ml min-'. At CLCr ' 20 ml min-' the normal dose should be reduced to < 20% of normal.4 Vaginal spotting was noted in three female patients and a gastro-intestinal haemorrhage that did not require transfusion in one male patient. These may be associated with the action of sulotroban.