Many pharmacokinetic studies have been undertaken following both intravenous and oral administration in diseased patients after acute or chronic administration. Studies were carried out on COLD patients (IV and PO routes), patients with renal insufficiency (PO route) and patients with hepatic insufficiency (PO route). Plasma almitrine bismesylate assays are performed by a simple, sensitive and specific technique using a thermoionic nitrogen detector. Pharmacokinetic results obtained are compared to those obtained on healthy volunteers and discussed in terms of absorption, distribution and elimination. Results show that for the same administered dose, pharmacokinetic profile in COLD patients is close to the pharmacokinetic profile obtained on healthy volunteers. After six months' treatment the levels are not dependent on the subject's age or weight. In patients with renal insufficiency total plasma clearance is unchanged, mean steady state levels will be the same as normal patients and almitrine bismesylate can be administered in renal subjects without a change in dosage. In patients with liver insufficiency results are more variable. Some subjects have the same profile as healthy volunteers but absorption is diminished in others. Regarding the variability in kinetics and potential for impaired elimination, almitrine bismesylate should be titrated carefully in hepatic insufficiency.