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Fluconazole-induced torsade de pointes.

OBJECTIVE: To present a case of fluconazole-associated torsade de pointes (TDP) and discuss fluconazole's role in causing TDP. CASE SUMMARY: A 68-year-old white woman with Candida glabrata isolated from a presacral abscess developed TDP eight days after commencing oral fluconazole The patient had no other risk factors for TDP, including coronary artery disease, cardiomyopathy, congestive heart failure, and electrolyte abnormalities There was a temporal association between the initiation of fluconazole and TDP. The TDP resolved when fluconazole was discontinued; however, the patient continued to have premature ventricular contractions and nonsustained ventricular tachycardia (NSVT) until six days after drug cessation DISCUSSION: Use of the Naranjo probability scale indicates a probable relationship between the use of fluconazole and the development of TDP. The possible mechanism is depression of rapidly activating delayed rectifier potassium currents. In our patient, there was no other etiology identified that could explain QT prolongation or TDP The complete disappearance of NSVT and premature ventricular contractions followed by normalization of QT interval after the drug was stopped strongly suggests fluconazole as the etiology. CONCLUSIONS: Clinicians should be aware that fluconazole, even at low doses, may cause prolongation of the QT interval, leading to TDP. Serial electrocardiographic monitoring may be considered when fluconazole is administered in patients who are at risk for ventricular arrhythmias.

Aged↗

Therapeutic dilemma of fluconazole prophylaxis in intensive care.

OBJECTIVE: To review the data concerning the use of prophylactic fluconazole in intensive care patients who are not immunocompromised. DATA SOURCE: Literature identified through MEDLINE (1966-March 2001) and recent abstracts of data presented at scientific meetings. DATA SYNTHESIS: The use of fluconazole as a prophylactic antifungal agent is well documented in patients who are immunocompromised or undergoing bone marrow or solid organ transplantation, with supportive results. Recently published data suggest that the use of fluconazole in high-risk surgical patients can be safe and effective for preventing certain candida infections. However, there is growing evidence that the use of fluconazole may be contributing to the higher prevalence of fluconazole-resistant fungal infections. CONCLUSIONS: The use of prophylactic fluconazole in nonneutropenic patients is controversial. Retrospective and surveillance studies of nosocomial fungal infections suggest that the use of fluconazole may be contributing to the shift in fungal flora causing these infections and that the isolates are more fluconazole resistant. Fluconazole prophylaxis in surgical patients may be justified in patients who are at the greatest risk of developing fungal infections, those requiring multiple intraabdominal surgeries, or those with recurrent gastrointestinal perforations or anastomotic leakages, but there is a lack of randomized controlled trials to recommend its widespread use at this time.

Antifungal Agents↗

Fluconazole vs itraconazole-flucytosine association in the treatment of esophageal candidiasis in AIDS patients. A double-blind, multicenter placebo-controlled study. The Candida Esophagitis Multicenter Italian Study (CEMIS) Group.

STUDY OBJECTIVE: To assess the role and the therapeutic efficacy of fluconazole and itraconazole-flucytosine association compared with placebo, in the treatment of endoscopically diagnosed esophageal candidiasis in a selected population of AIDS patients. DESIGN: Double-blind, placebo-controlled study. SETTING: University Hospitals and AIDS Centers. PATIENTS: Eighty-five HIV-positive patients (53 men and 32 women; mean age, 28 years) at first episode of esophageal candidiasis diagnosed by endoscopy (grades I to II of Kodsi's endoscopic classification and grades I to IIa of Barbaro's clinical classification). All the patients selected for the study provided informed consent. INTERVENTIONS: The patients have been double blindly randomized in 3 groups of patients in relation to pharmacologic therapy: (1) the patients of the first group (n = 30) received fluconazole (3 mg/kg daily orally) and placebo (100 mg/kg/daily orally); (2) the patients of the second group (n = 30) received itraconazole (3 mg/kg daily orally) and flucytosine (100 mg/kg daily orally); and (3) the patients of the third group (n = 25) received placebo (3 mg/kg daily orally) and placebo (100 mg/kg daily orally). After 2 weeks of treatment, the patients previously randomized to receive placebo only were double blindly randomized to receive fluconazole+placebo or itraconazole+flucytosine. To evaluate the efficacy of pharmacologic therapy, clinical and endoscopic examinations were performed at weeks 2 and 4 and at the end of follow-up (3 months). RESULTS: At week 2, endoscopic cure (grade 0) was observed in 68.9% of the fluconazole+placebo group and in 72.4% of the itraconazole+flucytosine group (relative risk, 0.95; 95% confidence interval [CI], 0.68 to 1.33; p = 0.772); partial endoscopic response (grade I) was observed in 22.7% of the placebo group. Clinical cure (grade 0) was observed in 75.8% of fluconazole+placebo group and in 72.4% of itraconazole+flucytosine group (relative risk, 1.05; 95% CI, 0.77 to 1.42; p = 0.764), with a difference statistically significant for both treatments in comparison to placebo group (p < 0.001). Partial clinical response (grade I) was observed in 27.3% of the placebo group. At the end of follow-up, endoscopic cure was observed in 89.8% of the fluconazole+placebo group and in 94.8% of the itraconazole+flucytosine group (relative risk, 0.97; 95% CI, 0.83 to 1.08; p = 0.695). Clinical cure was observed in 94.8% of the fluconazole+placebo group and in 97.3% of the itraconazole+flucytosine group (relative risk, 0.97; 95% CI, 0.89 to 1.07; p = 0.981). CONCLUSIONS: The results of this study have demonstrated that both fluconazole and itraconazole+flucytosine association are efficacious in short-term treatment of esophageal candidiasis in AIDS patients with a statistically significant difference in comparison to placebo. Both therapeutic regimens demonstrated a good therapeutic efficacy, without statistically significant difference, between them, in the rate of endoscopic and clinical cure. Itraconazole+flucytosine association may represent an alternative therapeutic regimen for patients with fluconazole-resistant Candida esophagitis.

AIDS-Related Opportunistic Infections↗

Preventing fungal infection in neutropenic patients with acute leukemia: fluconazole compared with oral amphotericin B.

OBJECTIVE: To compare the efficacy and tolerability of fluconazole and oral amphotericin B in preventing fungal infection in neutropenic patients with acute leukemia. DESIGN: A randomized, controlled, multicenter trial. SETTING: 30 hematologic units in tertiary care or university hospitals. PATIENTS: 820 consecutive, afebrile, adult patients with acute leukemia and chemotherapy-induced neutropenia. INTERVENTION: Patients were randomly assigned to receive fluconazole, 150 mg, as a once-daily capsule, or amphotericin B suspension, 500 mg every 6 hours. MEASUREMENTS: An intention-to-treat analysis was done for 820 patients: 420 treated with fluconazole and 400 treated with oral amphotericin B. RESULTS: Definite systemic fungal infection occurred in 2.6% of fluconazole recipients and 2.5% of amphotericin B recipients; suspected systemic fungal infection requiring the empiric use of intravenous amphotericin B occurred in 16% of fluconazole recipients and 21% of oral amphotericin B recipients, a difference of 5 percentage points (95% CI for difference, -0.02% to 10%; P = 0.07). Superficial fungal infection was documented in 1.7% of fluconazole recipients compared with 2.7% of amphotericin B recipients, a difference of one percentage point (CI of difference, -0.9% to 3%; P > 0.2). The distribution of fungal isolates in systemic and superficial fungal infection was similar in both groups. The overall mortality rate accounted for 10% in both groups. An excellent compliance was documented for 90% of patients treated with fluconazole compared with 72% of those treated with amphotericin B suspension, a difference of 18 percentage points (CI for difference, 13% to 23%). Side effects were documented less frequently in fluconazole than in amphotericin B recipients (1.4% compared with 7%, a difference of 5.6 percentage points; CI for difference, 2% to 8%; P < 0.01). CONCLUSION: Fluconazole was at least as effective as oral amphotericin B in preventing systemic and superficial fungal infection and the empiric use of amphotericin B in neutropenic patients with acute leukemia but was better tolerated.

Acute Disease↗

Intraocular penetration and effect on the retina of fluconazole.

The intraocular concentration of fluconazole was measured in nonvitrectomized and vitrectomized eyes after an intravenous administration of 5 or 25 mg/kg fluconazole in albino rabbits. Respective fluconazole concentrations in the aqueous, vitreous and serum 1 hour after administration were 2.87, 1.72 and 4.60 micrograms/ml at 5 mg/kg administration, and 14.93, 7.05 and 20.63 micrograms/ml at 25 mg/kg administration, indicating high and dose-dependent intraocular penetration of fluconazole. Intraocular penetration of intravenously administered fluconazole was moderately, not very much, enhanced by vitrectomy. The in-vitro electroretinogram (ERG) remained unchanged after perfusion with 20 micrograms/ml of fluconazole. The in-vivo ERG and the visual evoked potential was unchanged after the daily administration of 25 mg/kg fluconazole for 8 days. The toxicity of fluconazole on the retina would be low and within safety limits so far as it is used at clinical dosage. Fluconazole may have a place in the treatment of fungal ocular infections.

Animals↗

Stability of fluconazole and amino acids in parenteral nutrient solutions.

The stability of fluconazole and amino acids in parenteral nutrient (PN) solutions was studied. Amino acids at three concentrations (1.0%, 2.5%, and 5.0%) with 25% dextrose injection were combined with a high (1.75 mg/mL) or a low (0.5 mg/mL) concentration of fluconazole to form six combinations of PN solution and fluconazole. The solutions were visually inspected for precipitate, color change, or gas formation and tested for pH. By using high-performance liquid chromatography, the solutions were assayed for fluconazole concentration at zero, one, and two hours after preparation. The PN solution containing fluconazole 1.75 mg/mL and 5.0% amino acids was assayed for 14 amino acids at the same time points. There was no visual evidence of incompatibility in any of the fluconazole and PN solutions, and the pH of the solutions did not vary appreciably throughout the study period. The mean percentage of initial fluconazole concentration remaining at one and two hours was greater than 97% for all of the solutions studied. The mean percentage of initial amino acid concentration remaining at one and two hours was greater than 93% for each of the 14 amino acids assayed. When fluconazole 0.5 mg/mL or 1.75 mg/mL is mixed with PN solution containing 1.0%, 2.5%, or 5.0% amino acids and 25% dextrose injection, both fluconazole and amino acids are stable for up to two hours.

Amino Acids↗

[In vivo and in vitro antifungal activity of fluconazole].

We examined in vivo efficacy and in vitro activity of fluconazole, a novel triazole antifungal agent, and obtained results which are summarized as follows: 1. Fluconazole showed a higher serum concentration than ketoconazole after oral administration to mice. The 50% effective dose of fluconazole administered orally to mice was similar to that of fluconazole injected to mice intraperitoneally in a systemic candidiasis model. 2. Prophylactic effects of fluconazole were excellent against systemic candidiasis, cryptococcosis and aspergillosis in mice in comparison with those of ketoconazole and miconazole. 3. The multiple administration of fluconazole effectively decreased the number of viable cells of Candida albicans colonized in kidneys of mice when the serum level of fluconazole was kept to exceed its IC99 values against the inoculated pathogen. Thus, a good correlation between the in vitro activity of fluconazole and its in vivo efficacy was confirmed. In vivo efficacies of ketoconazole and miconazole, however, failed to reflect their marked in vitro activities. 4. C. albicans No. 32 developed no drug-resistance to fluconazole during transfers in medium containing fluonazole at a concentration of 1 micrograms/ml.

Animals↗

Pharmacokinetics of fluconazole in people with HIV infection: a population analysis.

1. The population pharmacokinetics of fluconazole have been investigated in 113 male subjects with HIV infection and AIDS. Plasma concentration-time data (between 1 and 17 observations per dose) were collected from individuals as part of a pharmacokinetic investigation (13 subjects) or during routine fluconazole therapy (100 subjects) for the treatment or prophylaxis of fungal infection. 2. A one-compartment pharmacokinetic model was used to describe the disposition of fluconazole after oral and intravenous infusion doses. Population pharmacokinetic parameters were generated using the NONMEM and P-PHARM computer programs. 3. The population estimates (calculated using NONMEM) of fluconazole clearance and volume of distribution were 0.78 l h-1 and 47.61, respectively. The intersubject variability for these parameters was 41% and 8%, respectively. The model-dependent estimate of the extent of absorption was 0.99 with an intersubject variability of 6%. Mean population estimates generated by NONMEM and P-PHARM were in close agreement. 4. Examination of the relationship between patient covariates and pharmacokinetic parameters indicated that intersubject variability in fluconazole clearance could in part be explained by the severity of disease (as indicated by CD4 + T-lymphocyte count) and renal function (indicated by estimated creatinine clearance). Other pharmacokinetic parameters were unaffected by these covariates. 5. Fluconazole clearance (estimated using NONMEM) in subjects with a CD4 + T-lymphocyte count less than and greater than 200 cells mm3 was 0.73 l h-1 (95% CI; 0.64-0.82 l h-1) and 0.99 l h-1 (95% CI; 0.86-1.12 l h-1), respectively. The regression model for fluconazole clearance that accounted for changes in renal function and disease severity was CL (l h-1) = 0.25 (33%) + 0.0057 (32%) x CLcr (in ml min-1) + 0.00068 (10%) x CD4 cell count (in cells mm-3) where intersubject variability (expressed as %CV) is shown in brackets. 6. Based on pharmacokinetic considerations a reduction in the dose of fluconazole would appear to be warranted in people with HIV infection who are seriously ill or who have compromised renal function. However, the emergence of resistance to fluconazole must also be considered when thinking of dosage adjustments.

Adult↗

Antifungal Prophylaxis in Severely Neutropenic Patients: How Much Fluconazole is Necessary?

OBJECTIVES: To evaluate the efficacy of low dose fluconazole treatment for the prevention of yeast colonization and infection in severely neutropenic patients. METHODS: An open randomized trial, comparing fluconazole (100 mg per day) with nystatin (800,000 IU per day), in a University Hospital setting. RESULTS: Antifungal prophylaxis was given during the period of neutropenia, defined as less than 500 polymorphonuclear cells (PMN)/mm3). Thirty-six patients were randomly assigned to fluconazole and 33 to nystatin treatment groups. New oropharyngeal colonizations were significantly reduced by fluconazole (P=0.005), and oropharyngeal infections occurred less frequently in the fluconazole group (3% versus 16%, P=0.07). Stool colonization was identical between both groups. Systemic fungal infections were rare; one fluconazole patient had pulmonary aspergillosis and one nystatin patient developped Candida pseudotropicalis fungemia. Empiric amphotericin B was given with the same frequency in both groups. No side effects were associated with fluconazole. However, the administration of nystatin became impossible for three patients because of vomiting and lack of compliance. CONCLUSIONS: Fluconazole (100 mg per day) is more effective than nystatin for the prevention of oropharyngeal yeast colonization. Comparison with results in the literature suggests that a 100-mg dose of fluconazole has similar effects to 200 or 400 mg per day.

Journal Article↗

[Diminution of antifungal activity of fluconazole associated with ibuprofen and piroxicam in experimental histoplasmosis of hamsters (Mesocricetus auratus)]

The aim of this study was to determine if tha association of non-steroid antiinflammatory drugs (piroxicam and ibuprofen) with fluconazole, affects the antifungal activity of the azole compound, in an experimental model histoplasmosis in hamsters (Mesocricetus auratus). Sixty hamsters were intracardially inoculated with 4x10(6) yeasts of Histoplasma capsulatum var. capsulatum. Treatments began one week after the challenge and continued for three weeks. The hamsters were divided in six groups of ten animals each and received the following treatment: 1- fluconazole 8 mg/kg/day; 2- ibuprofen 20 mg/kg/day; 3- piroxicam 20 mg/kg/day; 4- fluconazole+ibuprofen; 5- fluconazole+piroxicam and 6- only received the solvent of these drugs. One week after ending the treatment, all the animals were sacrified and the evaluation of the treatments was based on the results of blood cultures, on the determination of colony forming units per gram of spleen, and the histopathologic studies of the same organ. The animals treated with fluconazole plus ibuprofen or piroxicam showed more colony colony forming units per gram (3.9x10(7) and 3.3x10(7)) when compared with the animals treated with fluconazole alone (0.9x10(7)). The histopathologic results of the hamsters that received fluconazole showed well-organized granulomas with few yeast-like elements inside the macrophages. In contrast, those which received fluconazole associated with antiinflammatory drugs presented lax granulomas containing numerous yeast-like elements. These findings let us to conclude that non-steroids antiinflammatory drugs diminish the antifungal efficacy of fluconazole in this animal model.

Journal Article↗

Pharmacokinetics and the most suitable dosing regimen of fluconazole in critically ill patients receiving continuous hemodiafiltration.

OBJECTIVE: To evaluate fluconazole pharmacokinetics and the dosage best suited to maintain effective plasma concentration in patients with continuous hemodiafiltration. DESIGN AND SETTING: Prospective study in the general intensive care unit of a university hospital. PATIENTS: Four critically ill patients being treated with fluconazole and receiving continuous hemodiafiltration. INTERVENTIONS: Fluconazole was administered at three dosing regimens: 200 and 400 mg every 24 h, 400 mg every 12 h, and 800 mg every 24 h. MEASUREMENTS AND RESULTS: The following pharmacokinetic variables for fluconazole were obtained: The mean volume distribution of steady state dosed at 400 mg every 12 h and 800 mg every 24 h were 0.55+/-0.23 and 0.71+/-0.16 l/kg, half-life of the elimination phase 8.08+/-0.83 and 9.12+/-0.75 h, total body clearance of fluconazole 1.14+/-0.44 and 0.98+/-0.20 ml/kg per minute, respectively. None of the dosing regimens reached the effective plasma trough concentration of fluconazole; however, simulation study found the recommended dose. CONCLUSIONS: Continuous hemodiafiltration is highly effective in removing fluconazole from circulation. We recommend fluconazole to be dosed at 500-600 mg intravenously every 12 h in patients receiving hemodiafiltration. This dosing regimen resulted in adequate trough plasma levels for systemic fungal infection.

Adult↗

Pharmacokinetics of sequential intravenous and enteral fluconazole in critically ill surgical patients with invasive mycoses and compromised gastro-intestinal function.

OBJECTIVES: (1) To determine the pharmacokinetics of sequential intravenous and enteral fluconazole in the serum of surgical intensive care unit (ICU) patients with deep mycoses. (2) To determine the concentrations of fluconazole reached at the site of infection. (3) To determine if enteral administration of fluconazole, which has an important pharmaco-economic advantage, is justified in this specific patient group. DESIGN: Descriptive, sequential study as a part of a therapeutic drug monitoring programme. SETTING: Eighteen-bed surgical ICU in a referral centre. PATIENTS: Fourteen critically ill surgical patients with recent gastro-intestinal (GI) surgery and deep mycosis caused by a fluconazole-susceptible fungus and a calculated creatinine clearance of more than 40 ml/min. INTERVENTIONS: Fluconazole dosage regimen: 400 mg i. v. every 24 h with an extra dose of 400 mg i.v. after 12 h on day 1. If the clinical condition allowed enteral administration on day 4, the content of two capsules of 200 mg was given via the feeding tube with concomitant enteral feeds. MEASUREMENTS AND MAIN RESULTS: Serum, exudate from the site of infection and urine samples collected at assumed steady state ( after > or = 5 doses). Fluconazole concentrations were determined by high-performance liquid chromatography (HPLC). The mean area under the concentration curve (AUC0-24 h) in serum after enteral administration did not significantly differ from the AUC0-24 h during intravenous treatment. The elimination half-life was longer compared to healthy volunteers. The mean (95% CI) estimated bioavailability was 124 (90-158)%. The mean (95% CI) area under the concentration time curves (AUCs) achieved in the exudate from the site of infection were 67 (55-79)% of the AUCs reached in serum for both regimens. CONCLUSIONS: In critically ill patients with recent GI surgery and/or peritonitis the bioavailability of enteral fluconazole was adequate. The concentrations of fluconazole reached in exudate were lower than those in serum for both regimens, but adequate to treat most cases of deep mycoses in this specific patient group.

Antifungal Agents↗

Effects of fluconazole on viable cell count in experimental intraperitoneal Candida abscesses.

We investigated the effects of fluconazole in experimental intraperitoneal Candida abscesses in neutropenic mice treated with cyclophosphamide to assess a clinically appropriate method for the application of fluconazole in fungal infections in patients with neutropenia. The efficacy of fluconazole in fungal infection was investigated in treatments started immediately after Candida albicans inoculation and before C. albicans inoculation (preventive use of fluconazole). In this intraabdominal fungal abscess model, it was confirmed that fungi in already formed abscess were not reduced in number by fluconazole, even when those fungi were susceptible to fluconazole. Fluconazole was effective with both administration methods. We conclude from this study that the effect of the preventive use of fluconazole was equivalent to the effect when treatment was started immediately after fungal inoculation.

Abdominal Abscess↗

Review of fluconazole: a new triazole antifungal agent.

Fluconazole is a new triazole antifungal agent with unique pharmacokinetic properties. It can be administered orally or parenterally and achieves rapid distribution by either route, and its absorption is not affected by the presence of food. It has a plasma half-life of approximately 25-30 hr and approximately 70% of dose is excreted in the urine unchanged. There is linearity of fluconazole plasma concentrations over the dose range and the elimination rate is independent of dose. No effect has been seen on basal or ACTH-stimulated cortisol or on testosterone, estrogen, progesterone, or other steroid hormones, and there is no interaction with an oral contraceptive. No interaction with concomitantly administered cyclosporine has been documented, and there are no clinically significant differences in absorption when fluconazole is given in the presence or absence of cimetidine or food. Patients who are concomitantly receiving coumarin anticoagulants should be monitored because there is an interaction between fluconazole and such anticoagulants. Patients taking oral hypoglycemics and fluconazole should be monitored, because fluconazole has been shown to inhibit the metabolism of tolbutamide. Fluconazole has been successfully used to treat a variety of fungal infections in a variety of contexts including vaginal candidiasis; oropharyngeal candidiasis in immunocompromised patients, those with malignancies, transplant recipients, and patients with systemic sclerosis; patients with cryptococcal meningitis; and patients with fungal infections who were also treated with chemotherapy or radiation therapy. In the treatment of all of these infections with doses ranging from 50 mg to 400 mg a day of fluconazole, there has been a very low incidence of side effects (9.3%) reported, and only 1.1% of all patients were withdrawn from therapy.

Absorption↗

Fluconazole versus amphotericin B as empirical antifungal therapy of unexplained fever in granulocytopenic cancer patients: a pragmatic, multicentre, prospective and randomised clinical trial.

Amphotericin B, despite its intrinsic servere toxicity, is the most commonly used empirical antifungal therapy in cancer patients with unexplained fever not responding to empirical antibacterial therapy. The aim of this study was to show whether fluconazole was as effective as, and less toxic than, amphotericin, with no effort made to compare the antifungal activity of the two drugs. A group of 112 persistently febrile (> 38 degrees C) and granulocytopenic (< 1000 cells/mm3) cancer patients, not receiving any absorbable antifungal antibiotic for prophylaxis, with a mean age of 27 years (range 1-73 years), undergoing chemotherapy for a variety of malignancies and with a diagnosis of unexplained fever after at least 96 h of empirical antibacterial therapy, were randomised to receive either fluconazole (6 mg/kg/day up to 400 mg/day) or amphotericin B (0.8 mg/kg/day) as empirical antifungal treatment. Patients were required to have normal chest X-rays at randomisation, no previous history of aspergillosis and negative surveillance cultures for Aspergillus. The intention-to-treat analysis showed defervescence and survival without treatment modification in 42 of 56 patients (75%) in the fluconazole group and in 37 of 56 (66%) in the amphotericin B group (P = 0.4). Duration of therapy was 6 days (95% CI = 4-8 days) in both groups. Death occurred in 3 patients (5%) in the fluconazole and in 2 (4%) in the amphotericin B group. No fungal death was documented in either group. Adverse events developed in 18 of 56 patients (32%) in the fluconazole group and in 46 of 56 (82%) in the amphotericin B group (P < 0.001). In the amphotericin B group, 5 patients had treatment discontinued because of toxicity, versus none in the fluconazole group, a difference which approached statistical significance (P = 0.06). This study shows that fluconazole is by far less toxic than amphotericin B and suggests that it might be as effective as amphotericin B, in pragmatical terms and for this specific indication. However, numbers are too small to allow definitive conclusions about efficacy, and the use of fluconazole for this indication remains experimental. Future studies should try to identify patients more at risk of fungal infections, with the aim of individualising antifungal approaches.

Adolescent↗

The effect of clarithromycin, fluconazole, and rifabutin on sulfamethoxazole hydroxylamine formation in individuals with human immunodeficiency virus infection (AACTG 283).

BACKGROUND: Sulfamethoxazole hydroxylamine formation, in combination with long-term oxidative stress, is thought to be the cause of high rates of adverse drug reactions to sulfamethoxazole in human immunodeficiency virus (HIV)-infected subjects. Therefore the goal of this study was to determine the effect of fluconazole, clarithromycin, and rifabutin on sulfamethoxazole hydroxylamine formation in individuals with HIV-1 infection. METHODS: HIV-1-infected subjects (CD4 + count >/=200 cells/mm 3 ) were enrolled in a 2-part (A and B), open-label drug interaction study (Adult AIDS Clinical Trial Group [AACTG] 283). In part A (n = 9), subjects received cotrimoxazole (1 tablet of 800 mg sulfamethoxazole/160 mg trimethoprim daily) alone for 2 weeks and then, in a randomly assigned order, cotrimoxazole plus either fluconazole (200 mg daily), rifabutin (300 mg daily), or fluconazole plus rifabutin, each for a 2-week period. Part B (n = 12) was identical to part A except that clarithromycin (500 mg twice daily) was substituted for rifabutin. RESULTS: In part A, fluconazole decreased the area under the plasma concentration-time curve (AUC), percent of dose excreted in 24-hour urine, and formation clearance (CL f ) of the hydroxylamine by 37%, 53%, and 61%, respectively (paired t test, P < .05). Rifabutin increased the AUC, percent excreted, and CL f of the hydroxylamine by 55%, 45%, and 53%, respectively ( P < .05). Fluconazole plus rifabutin decreased the AUC, percent excreted, and CL f of the hydroxylamine by 21%, 37%, and 46%, respectively ( P < .05). In part B the fluconazole data were similar to those of part A. Overall, clarithromycin had no effect on hydroxylamine production. CONCLUSIONS: If the exposure (AUC) to sulfamethoxazole hydroxylamine is predictive of sulfamethoxazole toxicity, then rifabutin will increase and clarithromycin plus fluconazole or rifabutin plus fluconazole will decrease the rates of adverse reactions to sulfamethoxazole in HIV-infected subjects.

Adult↗

The effect of clarithromycin, fluconazole, and rifabutin on dapsone hydroxylamine formation in individuals with human immunodeficiency virus infection (AACTG 283).

BACKGROUND: Dapsone hydroxylamine formation is thought to be the cause of the high rates of adverse reactions to dapsone in human immunodeficiency virus (HIV)-infected individuals. Therefore we studied the effect of the commonly coadministered drugs fluconazole, clarithromycin, and rifabutin on hydroxylamine formation in individuals with HIV infection. METHODS: HIV-infected subjects (CD4 + > or =200 cells/mm 3 ) were enrolled in a 2-part (A or B) open-label drug interaction study. In part A, subjects (n = 12) received dapsone (100-mg tablet once daily) alone for 2 weeks and then, in a randomly assigned order, received dapsone and either fluconazole (200 mg daily), rifabutin (300 mg daily), or fluconazole plus rifabutin, each for a 2-week period. Part B (n = 11) was identical to part A except that clarithromycin (500 mg twice daily) was substituted for rifabutin. On the last study day of each 2-week period, plasma and urine were collected over ascorbic acid for 24 hours. RESULTS: In part A, fluconazole decreased the area under the plasma concentration-time curve, percent of dose excreted in 24-hour urine, and formation clearance of the hydroxylamine by 49%, 53%, and 55% (n = 12, P < .05), respectively. This inhibition of in vivo hydroxylamine formation was quantitatively consistent with that predicted from human liver microsomal experiments. Rifabutin had no effect on hydroxylamine area under the plasma concentration-time curve or percent excreted in 24-hour urine but increased formation clearance of the hydroxylamine by 92% (n = 12, P < .05). Dapsone clearance was increased by rifabutin or rifabutin plus fluconazole (67% and 38%, respectively) (n = 12, P < .05) but was unaffected by fluconazole or clarithromycin. In part B, hydroxylamine production was unaffected by clarithromycin but was affected by fluconazole in a manner identical to that in part A. CONCLUSIONS: On the basis of these data and with the assumption that the exposure to the hydroxylamine is a determinant of dapsone toxicity, we predict that coadministration of fluconazole should decrease the rate of adverse reactions to dapsone in persons with HIV infection but that rifabutin and clarithromycin will have no effect. When dapsone is given in combination with rifabutin, dapsone dosage adjustment may be necessary in light of the increase in dapsone clearance.

Adult↗

Fluconazole-induced hepatic cytochrome P450 gene expression and enzymatic activities in rats and mice.

This study was undertaken to examine the effects of the triazole antifungal agent fluconazole on the expression of hepatic cytochrome P450 (Cyp) genes and the activities of Cyp enzymes in male Sprague-Dawley rats and male CD-1 mice. Alkoxyresorufin O-dealkylation (AROD) methods were used as measures of Cyp enzyme activities. Western analyses identified specific Cyp isoforms. Quantitative real-time reverse-transcription polymerase chain reaction (quantitative real time-RT-PCR) assays were used to quantitate the mRNA expression of specific Cyp genes induced by this conazole. Rats and mice were administered fluconazole 2, 25, or 50 mg/kg bw/d by gavage daily for 14 days. In rats, fluconazole treatment (50 mg/kg bw/d) significantly induced pentoxyresorufin O-dealkylation (PROD), benzyloxyresorufin O-dealkylation (BROD), and ethoxyresorufin O-dealkylation (EROD) hepatic microsomal activities. Fluconazole treatment significantly increased rat hepatic mRNA expression of CYP2B1 and CYP3A23/3A1 with dose-related responses. The highest dose of fluconazole gave a 128-fold induction of CYP2B1 and a 4.6-fold induction of CYP3A23/3A1 mRNA. CYP3A2 mRNA levels were also overexpressed 5.6-7.2-fold depending on dose. Western immunoblots of rat hepatic microsomal proteins identified Cyp isoforms: CYP1A1, CYP1A2, CYP2B1/2, CYP3A23/3A1, and Cyp3A2 with increased levels of CYP2B1/2 and CYP3A23/3A1 proteins. In mice, fluconazole induced BROD, PROD, EROD, and methoxyresorufin O-dealkylation hepatic microsomal activities after treatment with 25 and 50 mg/kg bw/d. Fluconazole increased mouse hepatic mRNA expression of Cyp2b10 (1.9-fold) and Cyp3a11 (2.6-fold) in the 50 mg/kg bw/d treatment group. In summary, these results indicated that fluconazole, a triazole-containing conazole, clearly induced CYP2B and CYP3A families of isoforms in rat liver and Cyp2b and Cyp3a families of isoforms in mouse liver.

Animals↗