Pharmacokinetics Of Itraconazole Research Articles

Posttreatment itraconazole levels in the nail: New implications for treatment in onychomycosis

A problem in the treatment of onychomycosis is the lengthy duration of therapy. The pharmacokinetics of itraconazole suggest a potential for briefer treatment. This study was designed to investigate itraconazole nail kinetics in 39 patients with onychomycosis in relation to their therapeutic outcome. All patients received itraconazole for 3 months at a dose of 100 or 200 mg daily. Itraconazole levels of distal nail clippings were determined during a 6-month posttherapy period. Therapeutic itraconazole concentrations were found in the nail plates of fingernails and toenails for up to 6 months after treatment. Cure of the toenails was observed in 79% of the patients treated with the 200 mg dosage and in 26% of those treated with 100 mg at 6 months after therapy. The data suggest that the drug reaches the nail via incorporation into the matrix and by diffusion from the nail bed and is eliminated with regrowth of the nail after discontinuation of treatment.

The Clinical Pharmacokinetics of Itraconazole: An Overview

Itraconazole (R 51211) is the prototype of a class of triazole antifungals characterized by a high lipophilicity. This property determines to a large extent the pharmacokinetics of itraconazole and differentiates it from the hydrophilic triazole antifungal fluconazole. The pharmacokinetics of itraconazole in man are characterized by a good oral absorption, an extensive tissue distribution with tissue concentrations many times higher than in plasma, a relatively long elimination half-life of about one day and a biotransformation into a large number of metabolites. One of them, hydroxy-itraconazole, is antifungally active and explains why antifungal plasma levels, when measured by bioassay, are about three times the itraconazole levels measured by a specific HPLC-method. Distribution studies have shown that therapeutically active levels of itraconazole are maintained much longer in some infected tissues than in plasma. For instance, active levels persist for four days in the vaginal epithelium after a one-day treatment and for 3 weeks in the stratum corneum of the skin after treatment has been stopped. Unlike fluconazole, itraconazole does not interfere with mammalian drug metabolizing enzymes, minimizing the risk of interaction with concomitantly administered drugs. These pharmacokinetic properties may contribute to the high efficacy and safety of itraconazole in patients with various mycotic infections. New pharmaceutical formulations are being explored in order to broaden the application field of itraconazole to intravenous and oral therapy of patients with malabsorption.

The effects of food and dose on the oral systemic availability of itraconazole in healthy subjects

We have studied the influence of food and dose (50, 100, 200 mg) on the oral systemic availability of the broad spectrum antifungal itraconazole and the pharmacokinetics after repeated dosing of 100 mg in six healthy volunteers. The relative systemic availability of itraconazole capsules compared with solution averaged 39.8% in the fasting state but 102% in the post-prandial state. Food did not significantly affect the tmax of the capsules. Itraconazole AUC at single doses of 50, 100, and 200 mg had a ratio of 0.3:1:2.7, and the steady-state AUC (0-24) after 15 days of 100 mg was five times the single-dose AUC. These findings suggest non-linear itraconazole pharmacokinetics in the range of therapeutically used doses. Furthermore, capsules should be given shortly after a meal to ensure optimal oral systemic availability.

Itraconazole pharmacokinetics in patients with renal dysfunction.

The single-dose pharmacokinetics of 200 mg of oral itraconazole were studied in seven uremic patients, seven patients treated by hemodialysis, and five patients treated by continuous ambulatory peritoneal dialysis. Plasma concentration-versus-time profiles showed wide intersubject variation. This study could not demonstrate any significant effect of renal dysfunction and hemodialysis or continuous ambulatory peritoneal dialysis treatment upon the pharmacokinetics of itraconazole, and firm conclusions concerning dosing in such patients should await confirmation of our data in a larger patient population.

Pharmacokinetics of itraconazole following oral administration to normal volunteers.

The pharmacokinetics of itraconazole, an orally effective, broad-spectrum, systemic antifungal agent, were evaluated in five healthy male volunteers. Each subject was studied on days 1 and 15 at the following dosages: 100 mg once daily (regimen A), 200 mg once daily (regimen B), and 200 mg twice daily (regimen C). On each study day, itraconazole was administered with a standardized meal. Plasma samples were collected for 72 h postdose, and 24-h urine specimens were obtained. On day 1 of regimen C, plasma samples were collected following the second dose. Samples were assayed for itraconazole by a sensitive, reverse-phase, high-performance liquid chromatography method. Wide intersubject variations in itraconazole concentration in plasma versus time profiles were observed on all study days. Absorption appeared to be slow, with day 1 mean peak itraconazole concentrations in plasma of 110 ng/ml at 2.8 h (regimen A), 272 ng/ml at 3.0 h (regimen B), and 553 ng/ml at 3.4 h (regimen C). Mean peak itraconazole concentrations in plasma on day 15 were 412 ng/ml at 3.0 h (regimen A), 1,070 ng/ml at 4.4 h (regimen B), and 1,980 ng/ml at 6.0 h (regimen C). The steady state was achieved by day 13. Respective elimination half-lives on days 1 and 15 were 15 and 34 h (regimen A), 20.7, and 36.5 h (regimen B), and 25 and 41.7 h (regimen C), respectively. The areas under the plasma concentration versus time curves (0 to infinity) on day 1 were 1,320 (regimen A), 4,160 (regimen B), and 12,600 ng.h/ml (regimen C). With the exception of one patient on day 15 of regimen C, itraconazole was not detected in the urine. All data support dose-dependent pharmacokinetic behavior for itraconazole.

The influence of food on the pharmacokinetics of itraconazole in patients with superficial fungal infection

Itraconazole is a new, orally active triazole, which is related to ketoconazole and which is active against dermatophytes and Candida and Cryptococcus organisms. It is more potent than ketoconazole, is better absorbed with food, and does not suppress testosterone or Cortisol synthesis. In previous studies, daily 200 mg doses of itraconazole for 5 days cleared 80% of cases of pityriasis versicolor, and 90% of dermatophyte infections were cleared by daily 100 mg doses administered for 1 month. Twenty patients with superficial dermatophyte, Candida albicans, and pityriasis versicolor infections were treated with doses of 50 or 100 mg per day; in the first group of 10 patients, the drug was administered before breakfast and the other 10 patients were given their dose with breakfast. Itraconazole concentration was determined by high-performance liquid chromatography 3 hours after administration of first and last doses. Our findings showed that although treatment with 50-mg doses led to poorer results and lower plasma levels than 100-mg doses, taking the drug with breakfast gave much better results than taking it before.

Itraconazole pharmacokinetics in the female genital tract: plasma and tissue levels in patients undergoing hysterectomy after a single dose of 200 mg itraconazole

Twenty patients who underwent hysterectomy received a single dose of 200 mg itraconazole at different moments before surgery. At the moment of surgery, a urine sample, blood sample and tissue samples of different organs of the female genital tract were collected. Blood levels and tissue levels of itraconazole were measured by means of an HPLC method. Itraconazole blood levels were lower than the corresponding tissue levels in the various organs of the female genital tract. This finding for itraconazole is different from findings with ketoconazole, indicating that itraconazole has a higher affinity for tissue than ketoconazole. Urine levels of itraconazole were virtually undetectable in all samples. None of the patients complained of side-effects, and blood biochemical parameters all remained within the normal limits. The premedication with itraconazole had no effect whatsoever on the induction and maintenance of and recovery from the anaesthesia. No abnormal effects on ECG were observed.