PROTEIN-BINDING AND IVERMECTIN ESTIMATIONS IN PATIENTS WITH ONCHOCERCIASIS

We measured ivermectin in plasma, urine, and saliva of nine patients w ith onchocerciasis. The aim was to establish pharmacokinetic parameter s and to assess the most facile medium for use in monitoring complianc e. Binding of ivermectin to plasma proteins in vitro was also investig ated. The mean (+/-SEM) plasma values for the nine subjects were as fo llows: weight, 66.3 +/- 2.8 kg; dose, 11.11 +/- 0.4 mg; half-life, 56. 50 +/- 7.01 hours; clearance, 142.5 +/- 22.6 L/kg; volume of distribut ion, 9.91 +/- 2.67 L/kg; area under the plasma concentration-time curv e, 1545.3 +/- 190.5 ng/ml . hr; time to reach maximum concentration, 4 .7 +/- 0.5 hours; and maximum concentration, 38.2 +/- 5.8 ng/ml. Iverm ectin was not detected in the urine of any of the nine subjects. Low l evels were found in saliva. Blood specimens remain the only reliable b iologic fluid for assessment of compliance after ivermectin oral admin istration. Ivermectin binds specifically to human serum albumin.