Candidaurinary tract infections: treatment options

Candiduria is a nonspecific finding that occurs with contamination of a urine sample, colonization of an indwelling catheter and/or the bladder, symptomatic cystitis and invasive upper tract infection. Most patients are colonized and do not require antifungal therapy. Removing predisposing factors, such as indwelling catheters and antibiotics, will clear candiduria in almost 50% of asymptomatic patients. For patients with symptomatic Candida urinary tract infections, a variety of treatment options are available. Fluconazole is the antifungal agent of choice, achieving high urine concentrations with the oral formulation. Rarely, amphotericin B or flucytosine are used. Newer azole agents and echinocandins are not recommended for the treatment of urinary tract infections since they fail to achieve adequate urine concentrations.

Metabolic profiling of a potential antifungal drug, 3-(4-bromophenyl)-5-acetoxymethyl-2,5-dihydrofuran-2-one, in mouse urine using high-performance liquid chromatography with UV photodiode-array and mass spectrometric detection

3-(4-bromophenyl)-5-acetyloxymethyl-2,5-dihydrofuran-2-one (LNO-18-22) is a representative member of a novel group of potential antifungal drugs, derived from a natural 3,5-disubstituted butenolide, (-)incrustoporine, as a lead structure. This lipophilic compound is characterized by high in vitro antifungal activity and low acute toxicity. For the purpose of in vivo studies, a new bioanalytical high-performance liquid chromatographic method with UV photodiode-array and mass spectrometric detection (HPLC-PDA-MS), involving a direct injection of diluted mouse urine was developed and used in the evaluation of the metabolic profiling of this drug candidate. The separation of LNO-18-22 and its phase I metabolites was performed in 37 min on a 125 mmx4 mm chromatographic column with Purospher RP-18e using an acetonitrile-water gradient elution. Scan mode of UV detection (195-380 nm) was employed for the identification of the parent compound and its biotransformation products in the biomatrix. Finally, the identity of LNO-18-22 and its metabolites was confirmed using HPLC-MS analyses of the eluate. These experiments demonstrated the power of a comprehensive analytical approach based on the combination of xenobiochemical methods and the results from tandem HPLC-PDA-MS (chromatographic behaviour, UV and MS spectra of native metabolites versus synthetic standards). The chemical structures of five phase I LNO-18-22 metabolites and one phase II metabolite were elucidated in the mouse urine, with two of these metabolites having very unexpected structures.

Disposition of caspofungin: role of distribution in determining pharmacokinetics in plasma

The disposition of caspofungin, a parenteral antifungal drug, was investigated. Following a single, 1-h, intravenous infusion of 70 mg (200 microCi) of [(3)H]caspofungin to healthy men, plasma, urine, and feces were collected over 27 days in study A (n = 6) and plasma was collected over 26 weeks in study B (n = 7). Supportive data were obtained from a single-dose [(3)H]caspofungin tissue distribution study in rats (n = 3 animals/time point). Over 27 days in humans, 75.4% of radioactivity was recovered in urine (40.7%) and feces (34.4%). A long terminal phase (t(1/2) = 14.6 days) characterized much of the plasma drug profile of radioactivity, which remained quantifiable to 22.3 weeks. Mass balance calculations indicated that radioactivity in tissues peaked at 1.5 to 2 days at approximately 92% of the dose, and the rate of radioactivity excretion peaked at 6 to 7 days. Metabolism and excretion of caspofungin were very slow processes, and very little excretion or biotransformation occurred in the first 24 to 30 h postdose. Most of the area under the concentration-time curve of caspofungin was accounted for during this period, consistent with distribution-controlled clearance. The apparent distribution volume during this period indicated that this distribution process is uptake into tissue cells. Radioactivity was widely distributed in rats, with the highest concentrations in liver, kidney, lung, and spleen. Liver exhibited an extended uptake phase, peaking at 24 h with 35% of total dose in liver. The plasma profile of caspofungin is determined primarily by the rate of distribution of caspofungin from plasma into tissues.

Stripping voltammetric and polarographic techniques for the determination of anti-fungal ketoconazole on the mercury electrode

The electroanalytical behaviour of ketoconazole in Britton-Robinson buffer is described. The reduction process on the hanging mercury drop electrode (HMDE) gives rise to one peak over -1.6 V (vs. Ag/AgCl/sat.KCl), within the pH range studied (4.7-9.6). The results showed that the reduction of ketoconazole is irreversible and the limiting current is adsorption controlled. The dependence of the peak current on the concentration was studied by means of different polarographic and voltammetric techniques. Using adsorptive stripping differential pulse voltammetry (AdS-DPV), the detection limit (DL) reached was 5.3 x 10(-11) mol l(-1). Two procedures, based on differential pulse polarography (DPP) and AdS-DPV in aqueous medium were developed for the determination of ketoconazole in a gel formulation and spiked urine samples, respectively.

Efficacy of a single intravenous dose of amphotericin B for Candida urinary tract infections: further favorable experience

Studies in experimental animals and humans have shown that Amphotericin B (AmB) persists in urine for days to weeks after a single IV dose in levels that should inhibit candidal organisms and thereby obviate the need for frequent dosing. Including data from four previously described patients, we have now treated a total of 11 patients (12 episodes) with Candida urinary tract infections with single-dose AmB (six, Candida albicans; two, C. tropicalis; four, other nonalbicans Candida). The duration of candiduria prior to entry ranged from 18 to 180 days. Predisposing conditions included renal transplantation (1), diabetes mellitus (8), genitourinary stones (1) or anomalies (4), catheterization (2), and antibacterial therapy (11). A single patient was intolerant of AmB. Out of 11 evaluable candiduric episodes, eight resolved. Failure occurred in one patient with a chronic indwelling bladder catheter and in the allograft recipient. The data suggest that the sustained urinary excretion of AmB may permit successful single- or paucidose therapy of Candida urinary tract infections in some patients with a minimum of toxicity.

Pharmacokinetics and tissue distribution of a new partricin A derivative (N-dimethylaminoacetyl-partricin A 2-dimethylaminoethylamide diaspartate) in mice

A single-dose trial in mice (1.25 mg/kg SPA-S-753 or 1 mg/kg amphotericin B [AmB] by intravenous route) was performed to study the pharmacokinetics, tissue distribution, and urinary excretion of a new polyene, SPA-S-753 (N-dimethylaminoacetyl-partricin A 2-dimethylaminoethylamide diaspartate), in comparison with AmB. Antibiotic concentrations were determined by microbiological assay (agar diffusion method). The elimination half-lives in serum were 15.1 and 19.8 h, respectively, for SPA-S-753 and AmB; the area under the curve from 0 to infinity values were 49.3 for SPA-S-753 and 23.6 microg. h/mL for AmB, because of the higher serum levels of SPA-S-753 found just after administration. The tissue concentrations of SPA-S-753 were lower than those of AmB in liver and lungs but higher in the kidneys. The urine concentrations of SPA-S-753 and the percent of the administered dose recovered from the urine were quite low in mice, whereas those of AmB were higher.

Pharmacokinetics, excretion, and mass balance of 14C after administration of 14C-cholesterol-labeled AmBisome to healthy volunteers

Amphotericin B (AmB) in small unilamellar liposomes (AmBisome) provides higher plasma concentrations and greater safety than the conventional deoxycholate formulation. The authors compared the disposition of the liposome's drug and cholesterol components by measuring AmB and radioactivity in plasma, urine, and feces for 1 week after a single 2-hour infusion of 14C-cholesterol-labeled AmBisome (2 mg/kg, 1 microgCi/kg) in healthy adults (4 males, 1 female). The plasma profile of 14C-cholesterol differed from that of AmB, lacking an initial rapid disappearance phase, having a lower total clearance, and having a volume of distribution (0.13 L/kg) close to that of the plasma compartment. The biphasic disappearance and long plasma half-life (147 h) of 14C-cholesterol were similar to those of other low-clearance liposomes. This and the low clearance of 14C-cholesterol from the plasma compartment suggest that it served as a liposome marker. The plasma drug-lipid ratio fell during the study, showing that AmB was cleared from plasma more rapidly than cholesterol or liposomes and suggesting that the composition of the liposomes changed over time. 14C-radioactivity was recovered mainly in the feces (9.5% of dose), consistent with the catabolism of cholesterol to bile salts. Combined fecal and renal clearances were < 18% of total clearance, suggesting that most of the liposomal drug and lipid remained in the body 1 week after dosing. Thus, AmBisome remains in the circulation for an extended period of time while releasing AmB, resulting in its markedly altered pharmacokinetic and safety profiles.

Adsorptive behavior and electrochemical determination of the anti-fungal agent ketoconazole

The adsorptive properties and electrochemical behavior of ketoconazole, an oral anti-fungal agent, are demonstrated at a glassy carbon electrode. The adsorption of the compound obeys the Frumkin isotherm with an interaction factor (alpha) of 0.985 and adsorptive coefficient (beta) of 1.98 x 10(6) L mol(-1). The Gibbs energy of adsorption (deltaG) is -3.59 x 10(4) J mol(-1) at 25 degrees C. A very sensitive electroanalytical method has been developed for determination of the drug with a detection limit of 4.0 x 10(-11) mol L(-1). Relationships between stripping current and concentration of ketoconazole were linear in the range 10(-6)-10(-10) mol L(-1) with different preconcentration periods. The method has been used to measure the ketoconazole content of tablets.

Simultaneous administration of a cocktail of markers to measure renal drug elimination pathways: absence of a pharmacokinetic interaction between fluconazole and sinistrin, p-aminohippuric acid and pindolol

AIMS

Previous studies suggest that estimated creatinine clearance, the conventional measure of renal function, does not adequately reflect changes in renal drug handling in some patients, including the immunosuppressed. The aim of this study was to develop and validate a cocktail of markers, to be given in a single administration, capable of detecting alterations in the renal elimination pathways of glomerular filtration, tubular secretion and tubular reabsorption.

METHODS

Healthy male subjects (n = 12) received intravenously infused 2500 mg sinistrin (glomerular filtration) and 440 mg p-aminohippuric acid (PAH; anion secretion), and orally administered 100 mg fluconazole (reabsorption) and 15 mg rac-pindolol (cation secretion). The potential interaction between these markers was investigated in a pharmacokinetic study where markers (M) or fluconazole (F) were administered alone or together (M + F). Validated analytical methods were used to measure plasma and urine concentrations in order to quantify the renal handling of each marker. Plasma protein binding of fluconazole was measured by ultrafiltration. All subjects had an estimated creatinine clearance within the normal range. The renal clearance of each marker (mean+/- s.d.) was calculated as the ratio of the amount excreted in urine and the area-under-the-concentration-time curve. Statistical comparisons were made using a paired t-test and 95% confidence intervals were reported.

RESULTS

The renal clearances of sinistrin (M: 119 +/- 31 ml min(-1); M + F: 130 +/- 40 ml min(-1); P = 0.32), PAH (M: 469 +/- 145 ml min(-1); M + F: 467 +/- 146 ml min(-1); P = 0.95), R-pindolol (M: 204 +/- 41 ml min(-1); M + F: 190 +/- 41 ml min(-1); P = 0.39; n = 11), S-pindolol (M: 225 +/- 55 ml min(-1); M + F: 209 +/- 60 ml min(-1); P = 0.27; n = 11) and fluconazole (F: 14.9 +/- 3.8 ml min(-1); M + F: 13.6 +/- 3.4 ml min(-1); P = 0.16) were similar when the markers or fluconazole were administered alone (M or F) or as a cocktail (M + F).

CONCLUSIONS

This study found no interaction between markers and fluconazole in healthy male subjects, suggesting that a single administration of this cocktail of markers of different renal processes can be used to simultaneously investigate pathways of renal drug elimination.

Analytical validation for a series of marker compounds used to assess renal drug elimination processes

Renal drug elimination is determined by glomerular filtration, tubular secretion, and tubular reabsorption. Changes in the integrity of these processes influence renal drug clearance, and these changes may not be detected by conventional measures of renal function such as creatinine clearance. The aim of the current study was to examine the analytic issues needed to develop a cocktail of marker drugs (fluconazole, rac-pindolol, para-aminohippuric acid, sinistrin) to measure simultaneously the mechanisms contributing to renal clearance. High-performance liquid chromatographic methods of analysis for fluconazole, pindolol, para-aminohippuric acid, and creatinine and an enzymatic assay for sinistrin were developed or modified and then validated to allow determination of each of the compounds in both plasma and urine in the presence of all other marker drugs. A pilot clinical study in one volunteer was conducted to ensure that the assays were suitable for quantitating all the marker drugs to the sensitivity and specificity needed to allow accurate determination of individual renal clearances. The performance of all assays (plasma and urine) complied with published validation criteria. All standard curves displayed linearity over the concentration ranges required, with coefficients of correlation greater than 0.99. The precision of the interday and intraday variabilities of quality controls for each marker in plasma and urine were all less than 11.9% for each marker. Recoveries of markers (and internal standards) in plasma and urine were all at least 90%. All markers investigated were shown to be stable when plasma or urine was frozen and thawed. For all the assays developed, there were no interferences from other markers or endogenous substances. In a pilot clinical study, concentrations of all markers could be accurately and reproducibly determined for a sufficient duration of time after administration to calculate accurate renal clearance for each marker. This article presents details of the analytic techniques developed for measuring concentrations of marker drugs for different renal elimination processes administered as a single dose to define the processes contributing to renal drug elimination.

Practical aspects of liquid chromatography/electrospray tandem mass spectrometry for rapid identification of metabolites of a new antifungal agent SYN-2836 in dog urine

This report presents the structural elucidation of 12 urinary metabolites of SYN-2836, a new antifungal agent showing extensive metabolism in beagle dogs, using complementary liquid chromatography/tandem mass spectrometry (LC/MS/MS) methodologies. The 12 SYN-2836 metabolites were readily divided into four groups by considering that all three members of each group, although differing in masses, exhibited highly similar product ion mass spectra. This suggests that the metabolites within each group share a common major substructure. Therefore, all the grouped SYN-2836 metabolites were strategically identified by characterization of the major substructures followed by determination of the additional small substructures. This grouping strategy greatly facilitated the structural elucidation of these metabolites. Other strategies were also employed to achieve as rapid and unambiguous characterization of the SYN-2836 metabolites as possible.

Metabolites of caspofungin acetate, a potent antifungal agent, in human plasma and urine

Caspofungin acetate (MK-0991) is a semisynthetic pneumocandin derivative being developed as a parenteral antifungal agent with broad-spectrum activity against systemic infections such as those caused by Candida and Aspergillus species. Following a 1-h i.v. infusion of 70 mg of [(3)H]MK-0991 to healthy subjects, excretion of drug-related material was very slow, such that 41 and 35% of the dosed radioactivity was recovered in urine and feces, respectively, over 27 days. Plasma and urine samples collected around 24 h postdose contained predominantly unchanged MK-0991, together with trace amounts of a peptide hydrolysis product, M0, a linear peptide. However, at later sampling times, M0 proved to be the major circulating component, whereas corresponding urine specimens contained mainly the hydrolytic metabolites M1 and M2, together with M0 and unchanged MK-0991, whose cumulative urinary excretion over the first 16 days postdose represented 13, 71, 1, and 9%, respectively, of the urinary radioactivity. The major metabolite, M2, was highly polar and extremely unstable under acidic conditions when it was converted to a less polar product identified as N-acetyl-4(S)-hydroxy-4-(4-hydroxyphenyl)-L-threonine gamma-lactone. Derivatization of M2 in aqueous media led to its identification as the corresponding gamma-hydroxy acid, N-acetyl-4(S)-hydroxy-4-(4-hydroxyphenyl)-L-threonine. Metabolite M1, which was extremely polar, eluting from HPLC column just after the void volume, was identified by chemical derivatization as des-acetyl-M2. Thus, the major urinary and plasma metabolites of MK-0991 resulted from peptide hydrolysis and/or N-acetylation.

Adsorptive stripping voltammetric determination of ketoconazole in pharmaceutical preparations and urine using carbon paste electrodes

The oxidation of ketoconazole on a bare carbon paste electrode was studied voltammetrically. The results indicated that the process is irreversible and controlled by an adsorption-extraction process which allows the accumulation of the drug at the electrode surface. After the optimization of solution pH, accumulation variables and instrumental parameters, sensitive differential pulse and linear sweep voltammetric peaks were obtained whose peak currents were linearly proportional to the ketoconazole concentration over the ranges 2.4 x 10(-8)-4.8 x 10(-7) and 9.1 x 10(-7)-1.0 x 10(-5) M, respectively. Based on these findings, a simple procedure was developed for the determination of ketoconazole in human urine and formulations.

Novel sample preparation method facilitating identification of urinary drug metabolites by liquid chromatography-tandem mass spectrometry

A simple, efficient procedure was developed for the preparation of urine samples, which greatly facilitated the identification of the urinary metabolites of a new antifungal agent SYN-2836. The urine samples following dilution with acetonitrile (ACN) formed distinct upper (ACN) and lower (aqueous) solution phases. The SYN-2836 metabolites were concentrated in the upper solution except that two glucuronides were concentrated in the lower solution. The upper solutions, containing concentrated metabolites and significantly reduced endogenous polar species, were ideally suitable for the metabolite identification. This novel sample preparation procedure would be applicable in identification of urinary metabolites of other drugs and drug candidates.

Pharmacokinetics of intraperitoneal fluconazole during continuous cycling peritoneal dialysis

OBJECTIVE

To investigate the pharmacokinetic characteristics of intraperitoneal fluconazole in patients undergoing continuous cycling peritoneal dialysis (CCPD).

DESIGN

Prospective, nonrandomized, single-dose, open-label study.

PARTICIPANTS

Five noninfected volunteer CCPD patients.

INTERVENTIONS

Patients received a single dose of intraperitoneal fluconazole 200 mg during their long daytime dwell. Blood samples were collected before and 1, 3, 6, 12 (end of first dwell), 24 (after overnight cycling), 48, 72, 96, and 120 hours after dosing. Used dialysate was collected throughout the study. Unless the patient was anuric, urine was collected for the first 48 hours.

MAIN OUTCOME MEASURE

Fluconazole concentrations were assayed by gas-liquid chromatography. Pharmacokinetic parameters were calculated using standard noncompartmental techniques.

RESULTS

The bioavailability of intraperitoneal fluconazole was 96% +/- 2% over a 12-hour dwell, absorption half-life was 2.5 +/- 1.2 hours, serum elimination half-life was 71.65 +/- 12.76 hours, and volume of distribution was 0.66 +/- 0.13 L/kg. Peritoneal clearance was 5.96 +/- 0.93 mL/min and proportional to total dialysate volume. Renal clearance was proportional to renal creatinine clearance.

CONCLUSIONS

Current treatment guidelines for fungal peritonitis suggest fluconazole 200 mg intraperitoneally every 24 hours. Our data suggest that this dose, administered every 48 hours, is more than sufficient to maintain serum and peritoneal concentrations above the minimum inhibitory concentration for most Candida spp. Other factors, such as residual renal function and dialysis prescription, may also need to be considered.

Pharmacokinetics of terbinafine and five known metabolites in children, after oral administration

As an extensive study, the pharmacokinetics of terbinafine and five known metabolites have been investigated after single and repeated oral administration to 12 pediatric patients. After single administration of 125 mg terbinafine, four compounds were unconjugated and the hydroxymetabolites appeared in trace amounts as glucuronides. The main metabolites in plasma were unconjugated carboxy compounds. Kinetics of terbinafine and N-desmethylterbinafine metabolite were comparable. The interindividual AUCt variability was similar for terbinafine, N-desmethylterbinafine and carboxyterbinafine. In urine, the major fraction was the hydrophilic unconjugated N-desmethyl-carboxyterbinafine (15%). After repeated administration of 125 mg day(-1), mean trough levels of terbinafine, N-desmethylterbinafine, carboxyterbinafine and N-desmethylhydroxy-terbinafine, and also that of hydroxyterbinafine metabolite were similar, for each compound, on days 21, 42 and 56 denoting that steady state was reached at least on day 21 and no accumulation occurred between days 21 and 56.

Preliminary animal pharmacokinetics of the parenteral antifungal agent MK-0991 (L-743,872)

MK-0991 (L-743,872) is a potent antifungal agent featuring long half-life pharmacokinetics. The pharmacokinetics of MK-0991 administered intravenously to mice, rats, rhesus monkeys, and chimpanzees is presented. Unique to MK-0991 is its consistent cross-species performance. The range of values for the pharmacokinetic parameters were as follows: clearance, 0.26 to 0.51 ml/min/kg; half-life, 5.2 to 7.6 h; and distributive volume, 0.11 to 0.27 liters/kg. The level of protein binding of MK-0991 was determined to be 96% in mouse and human serum. The compound exhibited high affinities for human serum albumin and at least two lipid components. The rationale for the selection of MK-0991 as a drug development candidate was based on its two- to threefold superior pharmacokinetic performance in chimpanzees over the performance of an otherwise equivalent analog, L-733,560. Once-daily dosing for MK-0991 is indicated by a graphical comparison of levels in the circulations of chimpanzees and mice. In a study of the pharmacokinetics of MK-0991 in mouse tissue, the organs were assayed following intraperitoneal administration. The area under the concentration-versus-time curves (AUC) segregated the tissues into three exposure categories relative to plasma. The tissues with greater exposure than that for plasma were liver (16 times), kidney (3 times), and large intestine (2 times). The exposure for small intestine, lung, and spleen were equivalent to that for plasma. Organs with lower levels of exposure were the heart (0.3 times that for plasma), thigh (0.2 times), and brain (0.06 times). Kinetically, drug was cleared more slowly from all tissues than from plasma, indicating that terminal-phase equilibrium had not been achieved by 24 h. Thus, some measure of accumulation is predicted for all tissues. Single daily doses of MK-0991 should provide adequate systemic levels of fungicidal activity as a result of its long half-life pharmacokinetics, wide distribution, and slowly accumulating concentrations in tissue.

Contribution to the determination of the chemotherapeutic drug G1 in biological fluids

A sensitive gas chromatographic method for the quantitative determination of the new antibacterial and antifungal drug G1, 1-(5-bromofuran-2-yl)-2-bromo-2-nitroethene, has been optimized. The method involves a fast and single extraction step from spiked serum and urine samples. The G1 drug was quantified using an internal standard method and by means of a nitrogen-selective detector. The results are statistically significant and show that mean levels of G1 as low as 1 microg ml(-1) can be measured accurately.

Pharmacokinetics of oral fluconazole when used for prophylaxis in bone marrow transplant recipients

The pharmacokinetics of fluconazole was investigated in 20 bone marrow transplant patients following oral administration of 200 mg of this drug. Blood samples were collected from each patient at different time intervals within 48 h after the first dose, and fluconazole was measured in plasma by high-performance liquid chromatography with UV detection. Urine was collected from 14 of these patients and analyzed similarly. The plasma concentration-time data exhibited the characteristics of the one-compartment model with first-order absorption quite well. The means +/- standard deviations of half-lives for absorption and elimination, peak concentration, time to peak, mean residence time, apparent volumes of distribution, area under the curve, and apparent oral clearance observed in these patients were 2.84 +/- 1.34 h, 19.94 +/- 18.7 h, 4.45 +/- 1.86 microg/ml, 8.34 +/- 5.97 h, 39.57 +/- 20.5 h, 0.874 +/- 0.48 liter/kg, 156.0 +/- 60.6 microg x h/ml, and 0.0256 +/- 0.0138 liter/h x kg, respectively. The amount of fluconazole excreted in urine in 24 h was 67.1 +/- 83 mg, which represents 33.55% +/- 41.6% of the dose administered. Patients who developed hemorrhagic cystitis excreted significantly (P < or = 0.0094) more fluconazole in 24 h than did those who did not.

Effect of food on the pharmacokinetics of a new hydroxypropyl-beta-cyclodextrin formulation of itraconazole

STUDY OBJECTIVE

To compare the pharmacokinetics of a single 100-mg oral dose of itraconazole administered as 10 ml of a 10-mg/ml itraconazole solution in hydroxypropyl-beta-cyclodextrin under fasting versus postprandial conditions.

DESIGN

Open-label, two-way, randomized, crossover study.

SETTING

Janssen Research Foundation, Belgium.

PATIENTS

Twelve healthy volunteers.

INTERVENTIONS

Blood samples were obtained for pharmacokinetic analyses immediately before dosing and at regular intervals up to 96 hours after each dose. Blood and urine samples were obtained for hematologic, biochemical, and urinary safety analyses at baseline and at the end of the study.

MEASUREMENTS AND MAIN RESULTS

The mean peak plasma concentrations of both itraconazole and its active metabolite hydroxy-itraconazole were significantly higher under fasting conditions than under postprandial conditions. The mean times to peak concentration for both the parent compound and its metabolite were significantly shorter under fasting than under nonfasting conditions. The mean areas under the curve (AUC0-infinity and AUC0-24 hrs) were also significantly higher under fasting than under postprandial conditions.

CONCLUSIONS

Our findings suggest that the higher bioavailability of this new formulation of itraconazole may be of benefit in seriously ill patients who are not able to ingest adequate quantities of food. The fact that the solution was also well tolerated and was not associated with clinically significant changes in any laboratory value further underscores the potential utility of this dosing form.

Pharmacokinetics and metabolism of genaconazole, a potent antifungal drug, in men

The pharmacokinetics of genaconazole, a racemic triazole antifungal agent comprising 50% RR and 50% SS enantiomers, were studied in 12 healthy male volunteers after a single oral dose of 200 mg. The serum samples were analyzed for the two enantiomers by using a chiral high-pressure liquid chromatography assay. The concentrations of the RR and SS enantiomers in serum were virtually identical. The mean values for the maximum concentrations in serum (Cmax) (1.7 micrograms/ml), times to Cmax (4.0 to 4.2 h), half-lives (83 h), and areas under the concentration-time curve from 0 h to infinity (195 to 199 micrograms.h/ml) were similar for the two enantiomers. The results showed that the pharmacokinetic profiles of the two enantiomers were similar after a single oral dosing of the racemate. The pharmacokinetics of the RR enantiomer were also evaluated in 12 healthy male volunteers after a single oral dose of 100 or 200 mg. The ratios of the Cmaxs and of the areas under the concentration-time curves from 0 h to infinity for the two doses were about 2, indicating a dose proportionality. In a separate study, six healthy male volunteers received a single oral dose of 50 mg of 14C-labeled genaconazole. The Cmax values for total radioactivity (14C) and intact genaconazole were virtually identical (0.6 micrograms/ml). The mean half-lives in serum were about 73 h for both total radioactivity and genaconazole. The amounts of total radioactivity excreted in the 0 to 240-h interval (representing approximately three half-lives) in urine and feces were 66.6 and 9.3% of the dose, respectively; 64.4% of the dose was excreted in urine as parent drug. There were no detectable metabolites in either serum or urine. The data demonstrate that genaconazole (racemate) is well absorbed, undergoes negligible biotransformation, and is slowly excreted, primarily in the urine.

Pharmacokinetics of terbinafine and of its five main metabolites in plasma and urine, following a single oral dose in healthy subjects

The plasma pharmacokinetics, and the urinary excretion, of terbinafine and its five main metabolites have been investigated after a single oral dose administration of 125 mg to 16 healthy subjects. In plasma, the highest concentrations are observed for the two carboxybutyl metabolites, with a predominance for the carboxybutylterbinafine. For this metabolite, as compared to terbinafine, the Cmax and AUC are 2.4 and 13 times higher respectively. The demethylterbinafine presents a plasma profile close to that of terbinafine. The two hydroxy metabolites are only found as glucuronide and are of minor importance. The apparent terminal half-lives of terbinafine, demethylterbinafine, and the two carboxy metabolites appear to be similar (approximately 25 h). As compared to the plasma concentration of total radioactivity observed after a single oral administration of the same dose of 14C-terbinafine, the parent drug and these five metabolites, account for more than 80% of the total radioactivity in plasma over the 0-48 h interval following administration. In urine, the major metabolite is demethylcarboxybutylterbinafine, which amounted to about 10% of the administered dose. Terbinafine and demethylterbinafine are only excreted as trace amounts in urine. Carboxybutylterbinafine and the two hydroxy metabolites are excreted in the range of 0.5-2% either as glucuronides or free. Urinary excretion over the 0-48 h interval of terbinafine and of the five metabolites amounted to about 14% of the administered dose. This is far below the level of total radioactivity measured in urine over the same interval (approximately 57%), after administration of 14C-terbinafine. This shows in contrast to plasma, that numerous other metabolites are present in urine.

Structural determination of a glucuronide conjugate of flucytosine in humans

The structure of a glucuronide metabolite of flucytosine (FC; 5-fluorocytosine), found in the urine of all patients treated with this antifungal drug, was determined. This compound is the O2-beta-glucuronide of FC. Its structure was established after isolation from urine and by comparing its spectroscopic characteristics with those of three FC glucuronides previously synthesized. This study is the first report of the identification of a glucuronide of a fluoropyrimidine drug in humans.

HPLC method for the quantitation of cispentacin enantiomers in rat urine

The two enantiomers of cispentacin, an antifungal antibiotic, are determined by reversed phase HPLC, after derivatization with Marfey's reagent, in 24 h urine samples collected from rats treated sc and iv with 20 mg/kg cispentacin racemate obtained by synthesis. The application range of the method is 25-250 mg/L for each enantiomer with a precision of 4.0-9.0%. Comparison with an authentic sample of natural origin (-)-cispentacin indicated that (-) enantiomer is excreted unchanged in smaller percentage than (+) enantiomer, which is almost completely eliminated as such.

Gas chromatographic and high-performance liquid chromatographic methods for the determination of genaconazole in biological fluids

Gas chromatographic (GC) and high-performance liquid chromatographic (HPLC) methods were developed for the determination of genaconazole in biological fluids. Both methods involved organic solvent extraction followed by solid-phase extraction on a C18 column. GC analysis utilized a megabore column (DB-17) with 63Ni electron-capture detection, whereas HPLC analysis utilized separation on a reversed-phase column with a methanol-phosphate buffer mixture as the mobile phase and quantitation by UV absorbance at 208 nm. Both methods yielded good linearity, accuracy and precision. The limit of quantitation (LOQ) was 0.025 microgram per ml of serum for GC and 0.2 microgram per ml of serum or 0.5 microgram per ml of urine for HPLC analysis. Both GC and HPLC methods were used for the determination of serum concentration-time curves of genaconazole in man following oral administration of a 50-mg dose.

Determination of SCH 39304 by megabore capillary gas-liquid chromatography

A gas-liquid chromatographic procedure for determination of SCH 39304 at low nanogram concentrations in serum, cerebrospinal fluid, and urine is presented. The methodology combines a high selectivity and sensitivity nitrogen-specific detector, a gas chromatograph equipped with a capillary "megabore" column, and an internal standard that is very similar in chemical structure to the drug being assayed. This method is suitable for both pharmacokinetic studies as well as for monitoring drug levels in patients receiving SCH 39304 for antifungal treatment.

Disposition of a new antiinfective agent 1,3-di(4-imidazolino-2-methoxyphenoxy)propane in male rats

The disposition of 1,3-di[4-imidazolino-2-methoxyphenoxy]propane (DMP) is described in male rats following a single 2.5 mg/kg intravenous or 10 mg/kg oral administration of DMP lactate in an aqueous (5% dextrose) solution. Following the intravenous administration, plasma concentrations of DMP declined in an apparent biexponential manner and were nonmeasurable after 24 hr. The mean terminal plasma elimination half-life was 14.9 hr. A volume of distribution of 18.7 liters/kg and a body clearance of 14.5 ml/min/kg were estimated. After oral administration, mean plasma concentrations of DMP reached a maximum of 39.6 ng/ml at 15 min and were nonmeasurable after 4 hr. The areas under the curve (AUC)0-24 of DMP was 2276 ng.hr/ml following the intravenous dose. The AUC0-4 was 68 ng.hr/ml following the oral dose. The AUC0-4 was 68 ng.hr/ml following the oral dose. Based on a comparison of AUC0-4, the oral bioavailability was 0.9%. A mean of 41.7 and 0.4% of the dose was excreted in urine as DMP following intravenous and oral administration, respectively. The tissue distribution and mass balance of total 14C were determined following a single 2.5 mg/kg intravenous administration of [14C]DMP.lactate. The concentrations of total 14C in all tissues were highest at 0.5 hr and declined with time thereafter. The highest concentration of 14C was in the kidneys, whereas the highest total amount was in the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of cutaneous Sulconazole nitrate in the hairless rat: absorption, excretion, tissue concentrations

After cutaneous application of radioactive solutions of Sulconazole nitrate in the hairless rat, the total absorption of the substance by the skin, estimated from the sum of the cumulative urinary and fecal excretions over 96 h, was 2.4% of the dose administered. The elimination reached a maximum between 6 and 24 h and was virtually complete after 96 h. The excretion was almost equally distributed between the urine and the feces, which corresponds to an intense elimination via the biliary tract. The quantities present in the stratum corneum, epidermis and dermis at the end of the period of contact constituted another estimation of the total absorption of the substance which confirmed the previous estimation (3.6% of the dose). The measurement of the concentrations of Sulconazole and its metabolites in the various layers of the skin revealed a high affinity of the substance for the stratum corneum, where it remained present in large quantities for more than 48 h. This affinity is due to the very intense lipophilia of the molecule. The concentrations in the other tissues were inversely proportional to the distance from the surface of the skin and were virtually nil in the circulating blood. These results suggest the absence of risk of systemic effects after cutaneous administration of Sulconazole and support the recommended therapeutic protocol in man (one administration per day).

Pharmacokinetic study of [14C]flutrimazole after oral and intravenous administration in dogs. Comparison with clotrimazole

This trial involved a comparative study using 6 Beagle dogs on the pharmacokinetics of 14C-labelled 1-[(2-fluorophenyl)(4-fluorophenyl)phenylmethyl]-1H-imidazole (flutrimazole, CAS 119006-77-8) and [14C]clotrimazole labelled in the imidazole ring. On the basis of a cross-over trial, each animal received a dose of 5 mg/kg (approx. 100 microCi) [14C]flutrimazole and [14C]clotrimazole, both intravenously and orally. The levels in plasma, urine and faeces of the total radioactivity, unchanged drug and the [14C]imidazole formed by metabolization of the unchanged drug were determined. Flutrimazole presented a biological half-life (t1/2) of 14.4 +/- 3.8 h and a clearance (Cl) of 6.7 +/- 0.8 l/h, while the values for clotrimazole were very different: t1/2 4.6 +/- 0.8 h and Cl: 13.6 +/- 1.0 l/h. After oral administration a fraction of absorbed dose (f) of 78 +/- 21% and bioavailability of 8.9 +/- 6.1% were calculated for flutrimazole. For clotrimazole, these were: 52 +/- 10% and 4.9 +/- 1.9%, respectively. Both drugs showed a significant first-pass effect, with 90% of the absorbed dose being metabolized before reaching the systemic circulation. The total recovery of radioactivity in faeces and urine 5 days after i.v. and oral administration was 58% and 68%, respectively, for [14C]flutrimazole, and 81% and 79% for [14C]clotrimazole. In both cases, most of the radioactivity was recovered in the faeces. The high radioactivity obtained in faeces after i.v. administration of both drugs confirms biliary elimination. For both flutrimazole and clotrimazole, less than 1% of the total recovered in the urine after i.v. administration was recovered as unchanged drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of L-671,329 in rhesus monkeys and DBA/2 mice

The time course of plasma drug levels and urinary recovery for two lipopeptide antifungal antibiotics, L-671,329 and cilofungin, were measured in male rhesus monkeys (Macaca mulatta) and in female DBA/2 mice. The antibiotics were administered intravenously at 10 mg/kg of body weight in phosphate-buffered saline-26% polyethylene glycol for the rhesus monkeys and in 5% dimethyl sulfoxide for the mice. Plasma and urine drug concentrations were determined by high-pressure liquid chromatography and/or a microbiological assay versus Aspergillus niger, and pharmacokinetic parameters were determined for both species. In each of the two rhesus crossover tests as well as in the mouse studies, the pharmacokinetics of the two compounds were similar; however, a marked difference was evident between species. The half-lives of L-671,329 and cilofungin in plasma were 39 and 34 min in the mice and averaged 1.8 and 2 h in the rhesus monkeys, respectively. In mice and rhesus monkeys, urinary recovery was less than 4% for both compounds.

Systemic absorption of 3H-fenticonazole after vaginal administration of 1 gram in patients

Fourteen women, five with normal cervicovaginal mucosa (Group 1), five with cervical carcinoma (Group 2) and four with relapsing vulvovaginal candidiasis (Group 3) were enrolled and completed this open clinical trial. Each subject received a single dose of 1.82 +/- 0.3 g on average of vaginal paste (for ovules) containing about 1000 mg of 3H-fenticonazole nitrate (266 microCi). Twelve hours after vaginal administration, the paste was removed by vaginal washing. Blood, urine and stool samples were collected at specified time intervals for five days. Plasma, urine, stools and all used material in contact with the paste were assayed for radioactivity. No measurable levels of radioactivity were detected in plasma of subjects of Groups 1 and 3 while in 4 of the 5 subjects with cervical carcinoma (Group 2) fenticonazole was detected during the 24 h after administration with a peak level at about 8 hours. For a period of 5 days, 0.4-1.5% of the dose on average was recovered from urine, and 0.18-0.32% from feces. Based on the excretion data, the extent of vaginal absorption of fenticonazole nitrate in women with vulvovaginal candidiasis was 1.81 +/- 0.57% of the dose, while in women with normal cervicovaginal mucosa it accounted for 0.58 +/- 0.28% of the administered dose. In patients with cervical carcinoma, absorption was 1.12 +/- 0.53%. The maximum amount absorbed corresponds to an exposure of about 0.4 mg/kg of fenticonazole nitrate (for a subject weighing 50 kg). Consequently, the vaginal administration of one ovule containing 1000 mg of fenticonazole nitrate seems to be devoid of risk for patients.

High-performance liquid chromatographic method for the quantification of several diamidine compounds with potential chemotherapeutic value

A high-performance liquid chromatographic method has been developed for the detection and quantification of pentamidine and pentamidine analogues of chemotherapeutic value in order to measure their concentration in physiological fluids. The compounds were extracted from urine over octadecyl solid-phase extraction columns, followed by chromatographic separation with an octadecyl reversed-phase column. For the mobile phase, a gradient of 31.5-37.5% acetonitrile in water, with sodium heptanesulfonate and tetramethylammonium chloride as ion modifiers, was used. This method was used to reliably detect levels as low as 341 ng/ml without concentration of the compounds during the solid-phase extraction. The assay was used to determine the effectiveness of several solid-phase extraction columns for isolating the compounds of interest and to quantify the amount of pentamidine and its analogues contained in the urine of dosed rats.

Analytical methods for the determination of terbinafine and its metabolites in human plasma, milk and urine

Analytical procedures have been developed for the determination of the allylamine antimycotic terbinafine (1) and its demethylderivate (2) in plasma, milk and urine, and the metabolite carboxy-terbinafine (3) in plasma and urine, as well as the further metabolites demethyl-carboxy-terbinafine (4) and naphthoic acid (5) in urine. HPLC-methods for plasma analysis employed either electrochemical detection (for 1 and 2) or UV-detection (for 3) following a protein precipitation step with methanol or sample extraction with hexane as appropriate. For quantitative urine analysis of substances 1-4 native urine samples were deconjugated, mixed with internal standard and injected by an autosampler into a microprocessor controlled HPLC-system. The substances were monitored by UV-absorption. The metabolite 5 was determined in urine after deconjugation, sample preparation with commercially available cartridges and silylation by automatized GC with fused silica capillary column and FID-detection. The standard calibration curves for the parent compound (1) and metabolites (2-5) are linear within the required analytical ranges. The detection limit for 1 and 2 is 50 ng/ml in plasma and 150 ng/ml in milk and for 3 in plasma 100 ng/ml. The detection limit in urine is 300 ng/ml for all substances (1-4) analyzed by HPLC and 50 ng/ml for 5 analyzed by GC.

Pharmacokinetics of two spiroarsoranes administered intravenously or orally to rabbits

The pharmacokinetics of two spiroarsorane molecules (1,2) were investigated after both intravenous bolus and an oral administration in rabbits. After iv administration of a 15-mg/kg dose, for the two substances, the plasma concentration-time curves were well described by an open two-compartmental model. The half-lives of the first phase were 0.47 +/- 0.12 and 0.27 +/- 0.02 h for 1 and 2, respectively. The half-lives of the terminal phase were of the same order of magnitude for the two substances: 4.38 +/- 0.24 and 6.03 +/- 1.14 h, respectively. Total plasma clearances were 2.47 +/- 0.44 and 0.81 +/- 0.04 L/h, respectively, and the steady-state volume of distribution of 2 (14.99 +/- 2.57 L) was larger than that of 1 (4.27 +/- 0.28 L). After oral administration, spiroarsorane 2 was not absorbed. The availability of the suspension of 1 was 18%. The rate of the absorption phase of 1 showed a saturation process, probably due to the solubility of the molecule. When increasing oral doses of 1 (15, 30, and 60 mg/kg) were administered, the plasma concentrations did not increase to the same extent.

Percutaneous absorption of sulconazole nitrate in humans

The percutaneous absorption of 1% sulconazole nitrate in a cream formulation containing 3H-labeled drug has been studied in seven human subjects. Two applications of 4.5 g each were made to 450 cm2 of abdominal skin at 0 and 12 h, and the site was washed at 24 h. The application site was subsequently washed at 24-h intervals for 3 consecutive days, and 6.7% of the dose was recovered in the urine and 2.0% in the feces following a 7-d collection period. Radioactivity was detectable in the plasma from 8-96 h, with a peak occurring at 24 h, and could also be recovered in the skin wash up to 96 h after application. Total percutaneous absorption of sulconazole was estimated to be 8.7-11.3% of the applied dose, considerably more than that previously reported for other imidazole drugs.

Determination of fluconazole in biological fluids by capillary column gas chromatography with a nitrogen detector

Fluconazole concentrations in biological fluids were determined by high-performance gas chromatography. A simple extraction procedure with chloroform, under basic conditions and after the addition of UK-47,265 as the internal standard and with no evaporation stage, was carried out prior to analysis. A solid injector and a 15-m capillary column, coated with a nonpolar phase and connected to a nitrogen-selective detector that afforded an excellent selectivity and sensitivity, constituted the gas chromatographic system. The duration of each analysis was less than 4 min and the minimum detectable serum concentration was 50 ng/mL. In five patients undergoing chronic peritoneal dialysis, the mean serum concentrations +/- SD at 1, 6, and 48 h after the intraperitoneal administration of a single dose of fluconazole were, respectively, 325 +/- 75, 928 +/- 159, and 607 +/- 80 ng/mL.

High-pressure liquid chromatographic method for determination of Sch 28191 in biological fluids

A high-pressure liquid chromatographic method has been developed for the measurement of N-D-ornithyl amphotericin B methyl ester (Sch 28191) in biological fluid. The method involves protein precipitation with methanol, followed by separation of the supernatant on a reverse-phase column and quantitation by absorbance at 405 nm. This technique resulted in a recovery of 97%. There was a good linear relationship between the peak height ratio and Sch 28191 concentrations ranging from 0.015 to 20 micrograms/ml. In addition, this method was specific for Sch 28191 since all of its analogs tested did not interfere with the assay. The method was reproducible with a lower limit of quantitation of 0.015 microgram/ml. Serum levels obtained from this method were in good agreement with those obtained from a microbiological assay only when drug concentrations were higher than 1.5 microgram/ml. The high-pressure liquid chromatographic method is useful in monitoring serum and urine drug levels in animals and should prove to be useful for pharmacokinetic studies of the drug with therapeutic doses in humans.

Antifungal activity in human urine and serum after ingestion of garlic (Allium sativum)

A fresh extract of garlic (Allium sativum) was administered orally to human volunteers. At intervals, serum and urine were collected and assayed for antifungal activity. The maximum tolerable dose was determined to be 25 ml of garlic extract. Larger amounts caused severe burning sensations in the esophagus and the stomach and vomiting. After oral ingestion of 25 ml of the extract, anticandidal and anticryptococcal activities were detected in undiluted serum 0.5 and 1 h after ingestion. No detectable antifungal activity was found in the excreted urine at any time after oral ingestion. Oral garlic is of limited value in the therapy of human fungal infections.

Laboratory assessment of the antimycotic drug clotrimazole

Laboratory studies on clotrimazole showed that it had marked activity in vitro against all the Candida spp. and Cryptococcus spp. tested, against almost all strains of dermatophytes, and against Aspergillus spp and other fungal genera responsible for systemic mycoses; it had limited activity towards Gram-positive bacteria. The majority of Candida strains required MICs below 1 mug/ml and MCCs below 2 mug/ml.Serum, urine, and faecal assays of clotrimazole were made by microbiological methods on five children who received 100 mg/kg/day clotrimazole for several weeks. In-vitro sensitivity tests and biological fluid drug assays are also reported on specimens from 18 patients in other hospitals receiving clotrimazole for severe candidosis; several were renal transplant cases. Similar investigations are reported on specimens from 18 patients with pulmonary aspergilloses. The significance of low levels of the drug in body fluids, even after prolonged therapy, is discussed, and it is suggested that clotrimazole may be the first of a long series of imidazole derivatives with varying pharmacological and therapeutic properties.

Systemic antifungal activity of pyrrolnitrin

The antifungal activity of pyrrolnitrin, previously shown to be effective against superficial infections, was evaluated against experimental systemic mycoses. Pyrrolnitrin was inhibitory in vitro at <0.78 to 100 mug/ml to Candida albicans, Cryptococcus neoformans, Blastomyces dermatitidis, Sporotrichum schenckii, and Histoplasma capsulatum. Pyrrolnitrin activity was reduced about 90% in sera. After multiple subcutaneous doses of pyrrolnitrin at 20 mg/kg, activity was recovered in mouse blood and urine as well as kidney, liver, and brain homogenates. Multiple daily doses (50 mg/kg) of this antibiotic were effective in reducing by 74% the number of viable cells of C. albicans recovered from kidney homogenates. Multiple doses (15 mg/kg) resulted in a 74% reduction in the number of C. neoformans from brain homogenates. Pyrrolnitrin was ineffective in reducing the recovery of B. dermatitidis or H. capsulatum from liver or spleen homogenates of infected mice. When compared with amphotericin B, hamycin, 5-fluorocytosine, and saramycetin, this antibiotic was less effective. This study indicates that pyrrolnitrin would have limited usefulness as a systemic antifungal agent.