Factors affecting plasma levels of ketoconazole during long-term treatment.

In the present study we intended to obtain information on the evolution of near-peak blood levels during long-term treatment. 56 patients with an indication for systemic treatment of nail or skin mycoses obtained a daily dose of 200 mg ketoconazole. They were periodically checked for blood level of ketoconazole, clinical and mycological status and enzyme values. The average blood level was 2.8 +/- 1.3 micrograms/ml plasma. The blood level was not influenced by the length of the treatment. A correlation between blood level and weight or sex was not observed, whereas a significant negative correlation occurred between blood level and age (age group 15-30 years: 3.9 +/- 1.3 micrograms/ml; 46-60 years: 2.4 +/- 0.9 micrograms/ml).