Monitoring acetazolamide treatment

Electron capture gas chromatography was used to determine plasma concentrations after various doses of acetazolamide. In 40 patients steady state plasma concentrations were determined for daily doses of 187.5, 375, 750, and 1000 mg. Mean plasma concentrations increased with increasing dosages but there were marked interindividual variations. Part of the interindividual variation was explained by a positive correlation between age and plasma concentration. In 10 patients with previously untreated glaucoma intraocular pressure (IOP) responses and plasma concentrations were determined for increasing doses of acetazolamide. Increasing IOP reductions were obtained up to a dose of 750 mg while a daily dose of 1000 mg acetazolamide had no further effect on IOP. The relationship between IOP reduction and plasma concentration showed great interindividual variations, from a pressure reduction of 11 mmHg at 6 micrograms/ml acetazolamide to a pressure reduction of 0 mmHg at 11 micrograms/ml. As a rule, the maximal effect on IOP was obtained at a plasma concentration between 5 and 10 micrograms/ml. In most patients a daily dose of 1000 mg resulted in plasma concentrations above 10 micrograms/ml.