ANTIFUNGAL PULSE THERAPY FOR ONYCHOMYCOSIS - A PHARMACOKINETIC AND PHARMACODYNAMIC INVESTIGATION OF MONTHLY CYCLES OF 1-WEEK PULSE THERAPY WITH ITRACONAZOLE

Background and Design: In the treatment of onychomycosis, oral therapi es have generally been given as a continuous-dosing regimen. For examp le, the suggested dose of itraconazole for the treatment of onychomyco sis has thus far been 200 mg/d for 3 months. Based on the advances in our understanding of the pharmacokinetics of itraconazole, we investig ated the efficacy and nail kinetics of intermittent pulse-dosing thera py with oral itraconazole in patients who were suffering from onychomy cosis. Fifty patients with confirmed onychomycosis of the toenails, pr edominantly Trichophyton rubrum, were recruited and randomly assigned to three (n=25) or four (n=25) pulses of 1-week itraconazole therapy ( 200 mg twice daily for each month). Clinical and mycological evaluatio n of the infected toenails, and determination of the drug levels in th e distal nail ends of the fingernails and toenails, were performed at the end of each month up to month 6 and then every 2 months up to 1 ye ar. Results: In the three-pulse treatment group, the mean concentratio n of itraconazole in the distal ends of the toenails ranged from 67 (m onth 1) to 471 (month 6) ng/g, and in the distal ends of the fingernai ls, it ranged from 103 (month 1) to 424 (month 6) ng/g. At month 11, t he drug was still present in the distal ends of the toenails at an ave rage concentration of 186 ng/g. The highest individual concentrations of 1064 and 1166 ng/g were reached at month 6 for toenails and fingern ails, respectively. At end-point follow-up, toenails in 84% of the pat ients were clinically cured with a negative potassium hydroxide prepar ation and culture in 72% and 80% of the patients, respectively. In the four-pulse treatment group, the mean concentration of itraconazole in the distal ends of the toenails ranged from 32 (month 1) to 623 (mont h 8) ng/g, and in the distal ends of the fingernails, it ranged from 4 2 (month 1) to 380 (month 6) ng/g. The highest individual concentratio ns of 1549 and 946 ng/g were reached at month 7 for toenails and at mo nth 9 for fingernails, respectively. At month 12, the drug was still p resent in the distal ends of the toenails at an average concentration of 196 ng/g. At end-point follow-up; toenails in 76% of the patients w ere clinically cured with a negative potassium hydroxide preparation a nd culture in 72% and 80% of the patients, respectively. There were no significant intergroup differences between the three- and four-pulse treatment groups for the primary efficacy parameters. The drug was wel l tolerated with no significant side effects in either patient group. Conclusions: Following pulse therapy with itraconazole (400 mg/d given for 1 week each month for 3 to 4 months), the drug has been detected in the distal ends of nails after the first pulse, and it has reached therapeutic concentrations with further therapy. After stopping the la st pulse, the drug remains in the nail plate at levels above 300 ng/g for several months. Clinical cure rates between 76% and 84% and negati ve mycological examination findings between 72% and 80%, respectively, were observed in toenail onychomycosis. The data suggest that pulse t herapy with itraconazole is an effective and safe treatment option for onychomycosis.