Cocaine is rapidly and extensively metabolized. Studies with 3H-labeled cocaine have demonstrated that the drug is biotransformed to at least ten metabolites in the rat, with the concentration of unchanged cocaine in the urine being less than 10% that of the metabolite benzoylecgonine [1]. Information on the metabolism and excretion of cocaine in man is limited. Montesinos [2] has reviewed investigations performed in the 1950s and 1960s on chewers of coca leaf. However, these studies not only used analytical methods less specific and sensitive than those available today, but also employed routes of administration different from those currently used for therapy [3] or abuse. Although several recent investigations have demonstrated that cocaine is extensively metabolized to benzoylecgonine in man [4,5] and that plasma cocaine levels diminish rapidly [6], knowledge concerning the extent and rate of metabolism and excretion of parent drug and metabolite is almost nonexistent. Wallace et al [7] measured the urinary excretion of cocaine and benzoylecgonine in ten patients who had been administered cocaine hydrochloride prior to rhinoplastic surgery. These studies were limited to the initial 24 h after drug administration and consisted of three consecutive 8-h collective specimens per patient. It was observed that the excretion of cocaine and benzoylecgonine diminishes rapidly, that benzoylecgonine concentrations in urine consistently exceeded the corresponding cocaine concentrations by a significant amount, and that the benzoylecgonine/cocaine ratios of urine concentrations varied significantly, demonstrating the impracticability of attempting to predict cocaine concentrations from benzoylecgonine data, or conversely.

A megabore column gas-liquid chromatographic method which uses nitrogen-phosphorus detection was developed for the analysis of fluconazole in plasma, serum, cerebrospinal fluid, or urine. The assay was linear from 0.2 to 200 ,Ig/ml and had an average coefficient of variation of 7%. The suitability of the assay for pharmacokinetic studies was demonstrated.Fluconazole 858; 2-(2,4-difluorophenyl)-1,3-bis (lH-1,2,4-triazol-1-yl)-2-propanol; Fig. 1] is a triazole compound with potent antifungal activity which is currently being evaluated in clinical trials (5). It is well absorbed after oral administration (4) and shows good penetration into cerebrospinal fluid (1, 3). Early analytical methods for assay of this compound in biological fluids, designed to support preliminary animal and human studies, were effective but rather complex. Both gas-liquid chromatographic and highperformance liquid chromatographic (HPLC) approaches were used (2, 3, 6). However, with this compound now in clinical trials, a simpler and more rapid and reliable analytical method was desirable for therapeutic drug monitoring. We therefore developed the following method, which uses megabore column gas-liquid chromatography with nitrogenselective detection. MATERIALS AND METHODSInstrumentation. A Varian 6000 (Varian Instruments, Walnut Creek, Calif.) gas chromatograph with a nitrogen-phosphorus detector operating at an applied voltage of 5 to 10 mV was employed. A fused silica DB-5 megabore column (45 m long, inner diameter of 0.55 mm; J. W. Scientific, Folsom, Calif.) with a 1-,um-thick bonded liquid phase was used. The instrument conditions were as follows: injector temperature, 225°C; detector temperature, 275°C; column temperature, 1900C.Reagents. Fluconazole and internal standard UK-54,373 Standards and controls. Plasma standards were prepared by adding appropriate amounts of fluconazole in methanol to tubes that had been washed in a chromic acid bath and then sonicated in water purified by ion exchange, carbon filter, and 0.45-,um filter. The methanol was removed either by blowing nitrogen or air into the tubes at room temperature or by vacuum. ,ug/ml were employed in each group of urine specimens analyzed. Controls of 2 and 7 ,ug of fluconazole per ml, prepared in the same manner as were the standards, were also included in each group of serum or urine specimens assayed.Assay procedure. To assay plasma, serum, or cerebrospinal fluid, 0.5 ml of specimen was pipetted into a tube fitted with a Teflon-lined cap. One level spoonful of a Coors 01 spatula filled with NaHCO3-Na2CO3 (2:1) was added to the specimen to adjust the pH to 9.0 and to provide a salting-out effect. A 10-ml sample of extracting solvent (methylene chloride containing 0.1875 ,g of the UK-54,373 internal standard per ml) was added to the tube, and the mixture was mechanically shaken for 15 min. The tube was subsequently centrifuged in a floor model centrifuge (model CU-5000; International Equipment Co., Needham Heights, Mass.) for 5 min at 2,000 rpm. The upper aqueous layer was ...

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A mixed-phase liquid chromatographic column was used to assay fluconazole in plasma, serum, and cerebrospinal fluid. The assay was linear from 0.2 to 20 tLg/ml, with an average coefficient of variation of less than 5%. The partitioning of the drug between serum and cerebrospinal fluid was determined for 34 patients.The method was demonstrated to be suitable for both pharmacokinetic studies and monitoring of patients receiving treatment with this antifungal agent.Fluconazole is part of a growing family of triazole antifungal drugs which exhibit a broad spectrum of activity. It has desirable pharmacologic properties, including a relatively long half-life, the ability to be administered either orally or parenterally, and good penetration into cerebrospinal fluid (CSF) (1,3,5). With respect to side effects, it is superior to imidazole antifungal drugs introduced earlier (8). It has already been approved by the U.S. Food and Drug Administration for the treatment of certain systemic fungal infections and is currently in clinical use in the United States and Europe as well as in clinical trials for other applications. A continuing increase in systemic fungal infections concomitant with growing immunosuppressed population established the relevance of fluconazole in the drug treatment arena. ' Several assays are currently in use for determining fluconazole concentrations in biologic specimens. Both gas-liquid chromatographic (2, 4) and high-performance liquid chromatographic (HPLC) (7) assays have been reported. Bioassay techniques are also available (6).The assay described in this report is an HPLC method that is done with a m-ixed-phase column and UV spectrophotometric detection. It has been developed for determining drug concentrations in serum, plasma, and cerebrospinal fluid (CSF).MATERIALS AND METHODS Instrumentation. A model 5020 (Varian Instruments, Walnut Creek, Calif.) liquid chromatograph with a variablewavelength UV detector (Varian UV-50 or equivalent) was used. A Varian mixed-phase PTHAA-5 liquid chromatographic column (15 cm long; 4-mm inner diameter) was used.Reagents. Fluconazole and internal standard UK-54,373 [2 -(2,4 -difluorophenyl) -1,3 -bis(lH -1,2,4 -triazol -1 -yl) -2-propanol; Fig. 1 Chromatographic conditions. The mobile phase was prepared by mixing acetonitrile with filtered 0.051 M monobasic phosphate buffer adjusted to pH of 3.0 at 15:85 (vol/vol). The flow rate was 0.9 ml/min. The UV detector was set at a wavelength of 210 nm. The HPLC apparatus was operated at room temperature (25 to 28°C).Standards and controls. Stock standards at concentrations of 1 and 100 ,ug/ml in methanol were prepared by placing appropriate amounts of fluconazole in polypropylene tubes with screw-cap tops and then adding 0.10 ml of methanol. Working serum standards with fluconazole concentrations of 0.0, 0.2, 0.5, 1.0, 2.0, 2.5, 5.0, 10.0, 15.0, 20.0, 40.0, 50.0, and 100 ,ug/ml were prepared by placing various amounts of the two stock standard solutions in 15-ml glass tubes, taking the methanol to near dryness, an...