Pharmacokinetics of naproxen in patients with hypoproteinemia

The pharmacokinetics of naproxen were studied in nine patients with hypoproteinemia with total protein counts between 4.5 and 5.5 g/100 ml. All patients received an oral dose of 250 mg naproxen. Plasma concentrations of the drug were determined spectrofluorometrically. In this kind of patient the drug follows a single-compartment kinetic model. The average value of Cmax is 18.55 +/- 7.05 micrograms/ml, far lower than that obtained in healthy volunteers. A linear relationship is established between the values of Cmax and the total protein concentration. The plasma protein binding is not modified in this kind of patient. The bioavailability compared with healthy volunteers receiving the same dose was 45.55%.