FLUCONAZOLE - COMPARISON OF PHARMACOKINETICS, THERAPY AND IN-VITRO SUSCEPTIBILITY

Fluconazole shows good penetration into the tissues and body fluids ex amined and a rapid equilibrium is achieved between the concentrations in the various compartments. The pharmacokinetics of fluconazole after intravenous or oral administration are proportional to the dose. This finding, together with the slow elimination of the triazole (t(1/2) 3 0 h), makes it easier to forecast the therapeutically effective dosage . Measurements of fluconazole concentrations in blood can be used to p redict levels in some tissues (lung, brain, gynaecological samples), b ody fluids (sputum, saliva, vaginal secretions) or exudates. Concentra tions in cerebrospinal fluid and vitreous humour of the eye reach appr oximately 80% of the levels found in blood. A very high proportion of fluconazole is excreted unchanged in the urine, where concentrations o f the drug are 10-20-fold higher than in blood. Whilst this pharmacoki netic profile is valuable in the treatment of fungal infections of the urinary tract, it also means that the dosage may need to be decreased in patients with renal impairment. The susceptibility of fungi to flu conazole in vitro and in vivo correlates well with the concentrations of the drug measured in various compartments of the body.