Simplified bioassay method for measurement of flucytosine or ketoconazole

Therapeutic potential of the cytosine deaminase::uracil phosphoribosyl transferase/5-fluorocytosine suicide system for canine melanoma

We tested the efficacy of a yeast cytosine deaminase::uracil phosphoribosyl transferase/5-fluorocytosine (CDU/5-FC) non-viral suicide system on eight established canine melanoma cell lines. Albeit with different degree of sensitivity 5 days after lipofection, this system was significantly efficient killing melanoma cells, being four cell lines highly, two fairly and two not very sensitive to CDU/5-FC (their respective IC50 ranging from 0.20 to 800 μM 5-FC). Considering the relatively low lipofection efficiencies, a very strong bystander effect was verified in the eight cell lines: depending on the cell line, this effect accounted for most of the induced cell death (from 70% to 95%). In our assay conditions, we did not find useful interactions either with the herpes simplex thymidine kinase/ganciclovir suicide system (in sequential or simultaneous modality) or with cisplatin and bleomycin chemotherapeutic drugs. Furthermore, only two cell lines displayed limited useful interactions of the CDU/5-FC either with interferon-β gene transfer or the proteasome inhibitor bortezomib respectively. These results would preclude a wide use of these combinations. However, the fact that all the tested cells were significantly sensitive to the CDU/5-FC system encourages further research as a gene therapy tool for local control of canine melanoma.

Studies toward the comprehension of fungal-macroalgae interaction in cold marine regions from a biotechnological perspective

In marine ecosystems, macroalgae are the habitat for several microorganisms, fungi being among them. In the Antarctic benthic coastal ecosystem, macroalgae play a key role in organic matter cycling. In this study, 13 different macroalgae from Potter Cove and surrounding areas were sampled and 48 fungal isolates were obtained from six species, four Rhodophyta Ballia callitricha, Gigartina skottsbergii, Neuroglossum delesseriae and Palmaria decipiens, and two Phaeophyceae: Adenocystis utricularis and Ascoseira mirabilis. Fungal isolates mostly belonged to the Ascomycota phylum (Antarctomyces, Cadophora, Cladosporium, Penicillium, Phialocephala, and Pseudogymnoascus) and only one to the phylum Mucoromycota. Two of the isolates could not be identified to genus level, implying that Antarctica is a source of probable novel fungal taxa with enormous bioprospecting and biotechnological potential. 73% of the fungal isolates were moderate eurypsychrophilic (they grew at 5-25 °C), 12.5% were eurypsychrophilic and grew in the whole range, 12.5% of the isolates were narrow eurypsychrophilic (growth at 15-25 °C), and Mucoromycota AUe4 was classified as stenopsychrophilic as it grew at 5-15 °C. Organic extracts of seven macroalgae from which no fungal growth was obtained (three red algae Georgiella confluens, Gymnogongrus turquetii, Plocamium cartlagineum, and four brown algae Desmarestia anceps, D. Antarctica, Desmarestia menziesii, Himantothallus grandifolius) were tested against representative fungi of the genera isolated in this work. All extracts presented fungal inhibition, those from Plocamium cartilagineum and G. turquetii showed the best results, and for most of these macroalgae, this represents the first report of antifungal activity and constitute a promising source of compounds for future evaluation.

A reference laboratory experience of clinically achievable voriconazole, posaconazole, and itraconazole concentrations within the bloodstream and cerebral spinal fluid

Interest in antifungal therapeutic-drug monitoring has increased due to studies demonstrating associations between concentrations and outcomes. We reviewed the antifungal drug concentration database at our institution to gain a better understanding of achievable triazole drug levels. Antifungal concentrations were measured by high-performance liquid chromatography (HPLC), ultraperformance liquid chromatography and single-quadrupole mass spectrometry (UPLC/MS), or a bioassay. For this study, only confirmed human bloodstream (serum or plasma) and cerebral spinal fluid (CSF) concentrations of voriconazole, posaconazole, and itraconazole were analyzed. The largest numbers of bloodstream and CSF samples were found for voriconazole (14,370 and 173, respectively). Voriconazole bloodstream concentrations within the range of 1 to 5.5 μg/ml represented 50.6% of samples. Levels below the lower limit of quantification (0.2 μg/ml) were observed in 14.6% of samples, and 10.4% of samples had levels of ≥5.5 μg/ml. CSF voriconazole levels ranged from undetectable to 15.3 μg/ml and were <0.2 μg/ml in 11% of samples. Posaconazole bloodstream concentrations were ≥0.7 and ≥1.25 μg/ml in 41.6% and 18.9% of samples, respectively. Posaconazole was detected in only 4 of 22 CSF samples (undetectable to 0.56 μg/ml). Itraconazole levels, as measured by UPLC/MS, were ≥0.5 μg/ml in 43.3% and were undetectable in 33.9% of bloodstream samples. In contrast, when measured by a bioassay, itraconazole/hydroxyitraconazole bloodstream concentrations were ≥1.0 μg/ml in 72.9% of samples and were undetectable in 18% of samples. These results indicate that there is marked variability in bloodstream concentrations achieved with these three azoles. In addition, many levels within the bloodstream for each azole and for voriconazole and posaconazole in the CSF were undetectable or below thresholds associated with efficacy.

Antifungal therapy in a murine model of disseminated infection by Cryptococcus gattii

We have evaluated the efficacy of posaconazole (PSC), voriconazole (VRC), and amphotericin B (AMB) in a murine model of systemic infection by Cryptococcus gattii using immunocompromised animals and three clinical strains of the fungus. AMB was the most effective drug in prolonging the survival of mice and also in reducing tissue burden in all organs tested. To a lesser degree, VRC at 60 mg/kg of body weight in lung tissue and PSC at 40 mg/kg also in spleen demonstrated good efficacy in reducing the fungal load. The PSC and VRC levels in serum and brain tissue, determined by an agar diffusion bioassay method at 4 h after the last dose of the therapy, were above the corresponding MIC values. However, these drugs were not able to reduce the fungal load in brain tissue. Our results demonstrated that PSC and, to a lesser degree, VRC, have fungistatic activity and potential for the treatment of human pulmonary cryptococcosis.

Murine model of a disseminated infection by the novel fungus Fonsecaea monophora and successful treatment with posaconazole

We have evaluated the efficacy of posaconazole, amphotericin B, and itraconazole in a murine model of disseminated infection by Fonsecaea monophora. Of these three antifungal drugs tested, posaconazole prolonged survival significantly and reduced the fungal load in most of the organs tested. Bioassay studies demonstrated the relationship between posaconazole levels and dose escalation in serum and brain tissue. Posaconazole may have a clinical role in the treatment of disseminated infections by F. monophora.

Delivery of Antifungal Agents Using Bioactive and Nonbioactive Bone Cements

Background:

Management of fungal osteomyelitis is prolonged and frequently unsuccessful. Antifungal-impregnated cement is sometimes used as adjunctive therapy.

Objective:

To examine the release of antifungals from biodegradable and nonbiodegradable cement carriers.

Methods:

In vitro methods were used to assess antifungal drug release and antifungal activity of impregnated cements commonly used as adjunctive treatment of osteomyelitis. Cements included thermoplastic, nonbioactive polymers (polymethylmethacrylate [PMMA]) or bioactive agents (hydroxyapatite [HAP], β-tricalcium phosphate [β-TCP]) and were formed into spheres (beads).

Results:

Amphotericin B provided consistent supernatant concentrations (release), between 1.75 and 2.0 ug/mL, over 110 days from all bone cements. Flucytosine and fluconazole were observed for 33–42 days before becoming undetectable from a nonbioactive sphere and 18–22 days from a bioactive sphere. Serum concentrations for micafungin, terbinafine, and anidulafungin impregnated into PMMA rapidly became undetectable, regardless of the matrix used. Investigational β-TCP spheres prolonged release for fluconazole and micafungin, but had no effect on amphotericin B. Serum calcium concentrations decreased 60–80% in all HAP-impregnated drug sphere supernatants. Only amphotericin B–impregnated PMMA impacted supernatant calcium, decreasing concentrations by 50–60%. The antifungal-impregnated beads did not appear to be toxic to osteoblasts during 72 hours of exposure in tissue culture medium.

Conclusions:

Elution characteristics of most antifungals from bone cement spheres are probably not optima) for treatment of deep-seated fungal infections if a similar phenomenon of antifungal release manifests in vivo. Ceramic nonabsorbable impregnated devices must be removed after their lifespan expires and may necessitate another surgical procedure that can increase surgical risk and cost. Bioactive osteoconductive materials may provide a surgical alternative to nonabsorbable matrices. However, there have been no controlled trials demonstrating improved therapeutic outcomes with local therapy and assessing whether biodegradable materials act as a new focus for infection.

Simultaneous determination of docetaxel and ketoconazole in rat plasma by liquid chromatography/electrospray ionization tandem mass spectrometry

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for simultaneous quantification of docetaxel and ketoconazole in rat plasma with paclitaxel as internal standard (IS). The analytes were extracted from rat plasma by using a liquid-liquid extraction technique with ethyl acetate and the LC separation was performed on a Cosmosil-C(18) analytical column (150 mm x 2.0 mm i.d., Nacalai Tesque Inc., Japan). The extracted samples were analyzed with LC/MS/MS, operating in selected reaction monitoring (SRM) mode. The SRM transitions of precursor ions to product ions were 830.3-->549.1 (m/z) for docetaxel, 531.2-->489.3 (m/z) for ketoconazole, and 876.7-->307.9 (m/z) for the IS. The calibration curves were linear over the range of 2-500 ng/mL for docetaxel and 50-20 000 ng/mL for ketoconazole, with coefficients of correlation above 0.999. The limits of quantification for docetaxel and ketoconazole were both 2 ng/mL. The limit of detection for each analyte was 1 ng/mL. The intra- and inter-day precision (CV) of analysis were within 7%, and the accuracy ranged from 95 to 110%. The overall recoveries for docetaxel and ketoconazole were about 89.0% and 91.1%, respectively. The total analysis time was only 9.0 min. This quantitation method was successfully applied to the simultaneous determination of docetaxel and ketoconazole in rat plasma and some potential interaction was found in the current coadministration pharmacokinetic study. This established method was also utilized in the in vitro and in vivo drug-drug interaction study of docetaxel and ketoconazole (to be published).

Optimization and validation of a high-performance liquid chromatographic method with UV detection for the determination of ketoconazole in canine plasma

An isocratic high-performance liquid chromatographic method with detection at 240 nm was developed, optimized and validated for the determination of ketoconazole in canine plasma. 9-Acetylanthracene was used as internal standard. A Hypersil BDS RP-C18 column (250 mm x 4.6 mm, 5 microm particle size), was equilibrated with a mobile phase composed of methanol, water and diethylamine 74:26:0.1 (v/v/v). Its flow rate was 1 ml/min. The elution time for ketoconazole and 9-acetylanthracene was approximately 9 and 8 min, respectively. Calibration curves of ketoconazole in plasma were linear in the concentration range of 0.015-10 microg/ml. Limits of detection and quantification in plasma were 5 and 15 ng/ml, respectively. Recovery was greater than 95%. Intra- and inter-day relative standard deviation for ketoconazole in plasma was less than 3.1 and 4.7%, respectively. This method was applied to the determination of ketoconazole plasma levels after administration of a commercially available tablet to dogs.

Refractory Coccidioidomycosis Treated with Posaconazole

BACKGROUND

Disseminated coccidioidomycosis (which is caused by the endemic fungi of the genus Coccidioides) can be a life-threatening systemic fungal infection. Although conventional antifungal therapies have activity against Coccidioides, the disease can be refractory to standard therapies. Drug-associated toxicities also may limit the clinical utility of the standard antifungal drugs. In addition, relapses in patients with disseminated coccidioidomycosis are common, making long-term management of this disease challenging.

METHODS

We report the outcomes of 6 patients with coccidioidomycosis who were treated with posaconazole salvage therapy after treatment with conventional antifungal therapies failed to produce sustained clinical improvement. Patients were administered posaconazole oral suspension 800 mg/day in divided doses as part of an open-label clinical trial. A modified version of the Mycoses Study Group Coccidioides scoring system was used to evaluate the burden of disease. Posaconazole therapy resulted in rapid clinical improvements in the signs and symptoms of coccidioidomycosis.

RESULTS

At the end of therapy, 5 of 6 patients had successful outcomes. Posaconazole was well tolerated despite long-term administration (1-2 years), and 2 patients continued to receive posaconazole maintenance therapy at the time of writing.

CONCLUSIONS

The successful outcomes observed in this case series suggest that posaconazole is an effective therapy for coccidioidomycosis.

In vitro and in vivo efficacies of the new triazole albaconazole against Cryptococcus neoformans

The activity of albaconazole (UR-9825; J. Uriach & Cía. S.A., Barcelona, Spain) was compared to that of fluconazole against 12 isolates of Cryptococcus neoformans in vitro and against 1 isolate in vivo in a rabbit model of cryptococcal meningitis. Albaconazole was 100-fold more potent in vitro than fluconazole on a per-weight basis and was fungicidal at potentially relevant concentrations for two isolates. MICs ranged from </=0.0012 to 1.25 micro g/ml, with the MICs for most isolates being between 0.039 and 0.156 micro g/ml. Isolates were from human immunodeficiency virus (HIV)-infected and non-HIV-infected patients and were of serotypes A, B, and C; and the fluconazole MICs for some of the isolates were elevated. Infected rabbits were treated with either fluconazole or albaconazole at dosages ranging from 5 to 80 mg/kg of body weight/day. The peak concentrations of albaconazole in serum and cerebrospinal fluid (CSF) averaged 4.14 and 0.62 micro g/ml, respectively, in animals receiving 80 mg/kg/day. Comparison of the concentrations in serum and CSF suggested a level of CSF penetration of approximately 15%. Despite limited penetration into the subarachnoid space, at all three doses tested albaconazole was as effective as fluconazole for the treatment of cryptococcal meningitis in rabbits.

Breakthrough Scedosporium apiospermum (Pseudallescheria boydii) brain abscess during therapy for invasive pulmonary aspergillosis following high-risk allogeneic hematopoietic stem cell transplantation. Scedosporiasis and recent advances in antifungal therapy

Systemic scedosporiasis due to the anamorph or asexual form Scedosporium apiospermum (Pseudallescheria boydii) has become an important cause of opportunistic mycosis, especially in patients undergoing high-risk hematopoietic stem cell transplantation. We report a case of rapidly progressive cerebellar hyalohyphomycosis due to Scedosporium apiospermum in an allogeneic marrow graft recipient receiving treatment for severe graft-versus-host disease. This fatal breakthrough intracranial abscess, due to amphotericin B-resistant (minimum inhibitory concentration > 16 micro g/ml) mold, developed during the course of systemic antifungal therapy given for multicentric pulmonary aspergillosis. Despite treatment with high-dose Abelcet (10 mg/kg daily), free amphotericin B was not detected in postmortem cerebellar tissue. A broad-spectrum triazole-based agent (voriconazole/UK-109, 496--Vfend), and a novel fungal cell wall inhibitor, an echinocandin/pneumocandin analog (caspofungin/MK-0991--Cancidas), which exhibit excellent in vitro activity against most clinical Pseudallescheria boydii-Scedosporium apiospermum isolates, have recently become available in the United States and may provide much needed treatment options for patients at risk.

Determination of ketoconazole in human plasma by high-performance liquid chromatography-tandem mass spectrometry

A simple, rapid and specific high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS) has been developed and validated for the determination of ketoconazole in human plasma. The method used diethyl ether to extract the ketoconazole and the internal standard (I.S.) R51012 from alkalinized plasma sample. The LC separation was on a C(18) column (50 x 3 mm, 5 microm) using acetonitrile-water-formic acid (75:25:1, v/v/v) mobile phase. The retention times were approximately 1.8 min for both ketoconazole and the I.S. The MS-MS detection was by monitoring 531.2-->82.1 (m/z) for ketoconazole, and 733.5-->460.2 (m/z) for the I.S. The dynamic range was from 20.0 to 10000 ng/ml based on 0.1 ml plasma, with linear correlation coefficient of > or =0.9985. The run time was 2.5 min/injection. The recoveries of ketoconazole and the I.S. were 102 and 106%, respectively. The precision and accuracy of the control samples were with the relative standard deviations (RSDs) of < or =4.4% (n=6) and the relative errors (REs) from -0.6 to 1.4% for intra-day assay, and < or =8.6% RSD (n=18) and -1.4 to 0.9% RE for inter-day assay. The partial volume tests demonstrated good dilution integrity. Three freeze-thaw cycles, keeping plasma samples at ambient for 24 h, storing extracted samples at ambient for 24 h, and storing frozen plasma samples at approximately -20 degrees C for up to 2 months did not show substantial effects.

Liquid chromatographic determination of ketoconazole, a potent inhibitor of CYP3A4-mediated metabolism

A high-performance liquid chromatographic assay with UV detection has been developed for the determination of ketoconazole in human plasma. Quantitative extraction was achieved by a single solvent extraction involving a mixture of acetonitrile-n-butyl chloride (1:4, v/v). Ketoconazole and the internal standard (clotrimazole) were separated on a column packed with Inertsil ODS-80A material and a mobile phase composed of water-acetonitrile-tetrahydrofuran-ammonium hydroxide-triethylamine (45:50.2:2.5:0.1:0.1, v/v). The column effluent was monitored at a wavelength of 206 nm with a detector range set at 0.5. The calibration graph was linear in the range of 20-2000 ng/ml, with a lower limit of quantitation of 20.0 ng/ml. The extraction recoveries for ketoconazole and clotrimazole in human plasma were 93+/-9.7% and 83+/-10.0%, respectively. The developed method has been successfully applied to a clinical study to examine the pharmacokinetics of ketoconazole in a cancer patient.

Comparison of a new triazole antifungal agent, Schering 56592, with itraconazole and amphotericin B for treatment of histoplasmosis in immunocompetent mice

A murine model of intratracheally induced histoplasmosis was used to evaluate a new triazole antifungal agent, Schering (SCH) 56592, for treatment of histoplasmosis. MICs were determined for SCH 56592, amphotericin B, and itraconazole by testing yeast-phase isolates from 20 patients by a macrobroth dilution method. The MICs at which 90% of the isolates are inhibited were for 0.019 microgram/ml for SCH 56592, 0.5 microgram/ml for amphotericin B, and < or = 0.019 microgram/ml for itraconazole. Survival studies were done on groups of 10 B6C3F1 mice with a lethal inoculum of 10(5). All mice receiving 5, 1, or 0.25 mg of SCH 56592 per kg of body weight per day, 2.5 mg of amphotericin B per kg every other day (qod), or 75 mg of itraconazole per kg per day survived to day 29. Only 44% of mice receiving 5 mg of itraconazole/kg/day survived to day 29. Fungal burden studies done in similar groups of mice with a sublethal inoculum of 10(4) showed a reduction in CFUs and Histoplasma antigen levels in lung and spleen tissue in animals treated with 2 mg of amphotericin B/kg qod, 1 mg of SCH 56592/kg/day, and 75 mg of itraconazole/kg/day, but not in those treated with lower doses of the study drugs (0.2 mg of amphotericin B/kg qod, 0.1 mg of SCH 56592/kg/day, or 10 mg of itraconazole/kg/day). Serum drug concentrations were measured 3 and 24 h after the last dose in mice (groups of five to seven mice), each treated for 7 days with SCH 56592 (10 and 1 mg/kg/day) and itraconazole (75 and 10 mg/kg/day). Mean levels measured by bioassay were as follows: SCH 56592, 10 mg/kg/day (2.15 micrograms/ml at 3 h and 0.35 microgram/ml at 24 h); SCH 56592, 1 mg/kg/day (0.54 microgram/ml at 3 h and none detected at 24 h); itraconazole, 75 mg/kg/day (22.53 micrograms/ml at 3 h and none detected at 24 h); itraconazole, 10 mg/kg/day (1.33 micrograms/ml at 3 h and none detected at 24 h). Confirmatory results were obtained by high-pressure liquid chromatography assay. These studies show SCH 56592 to be a promising candidate for studies of treatment of histoplasmosis in humans.

Treatment of blastomycosis with itraconazole in 112 dogs

One hundred twelve client-owned dogs with blastomycosis were treated with itraconazole, 5 or 10 mg/kg/d. The first group of 70 dogs treated in 1987 and 1988 received 10 mg/kg/d (group 1), and the second group of 42 dogs treated after October 1988 received 5 mg/kg/d (group 2). Even though the groups were treated at different times, the dogs were similar in age and gender distribution, number of sites involved, and percent and severity of pulmonary involvement. The proportion of dogs cured with a 60-day course of itraconazole was similar for both groups (53.6% versus 54.3%) and for a second historical control group treated with amphotericin B (57%); the recurrence rate was also similar, 20%, 21.4%, and 20%, respectively. Dogs treated with itraconazole had similar mortality rates (25.7% at 5 mg/kg/d; 25% at 10 mg/kg/day) to those treated with amphotericin B (23%). Seventeen of the 23 dogs that died (74%), did so during the first week of treatment; these early deaths were usually attributed to respiratory failure. The only site of infection that was significantly associated with failure (death or recurrence) was the brain. There was a marked difference in survival times between dogs without lung disease or with mild lung disease compared with dogs with moderate or severe lung disease. Serum itraconazole concentrations reached steady state by 14 days of treatment. Dogs receiving 5 mg/kg/d of itraconazole (group 2) had mean serum concentrations of 3.55 +/- 2.81 mg/mL (range, 0.67 to 10.8 micrograms/mL), whereas dogs receiving 10 micrograms/kg/d (group 1) had mean concentrations of 13.46 +/- 8.49 micrograms/mL (range, 1.8 to 28 micrograms/mL) (P < or = .001). There was no association between cure and serum itraconazole concentrations. Dogs in group 1 had significantly more adverse effects than dogs in group 2 (P = .046). Anorexia was the most common adverse effect, occurring in 14.9% of dogs in group 1. Only 8% of dogs in group 2 had adverse effects. Serum concentrations of itraconazole were positively correlated with serum alkaline phosphatase and alanine aminotransferase activities. Our findings indicate that itraconazole administered at a dose of 5 mg/kg/d is the drug of choice for blastomycosis in dogs.

Systemic availability of itraconazole in lung transplantation

Systemic availability of itraconazole in lung transplantation was evaluated by serially measuring the bioactivity of itraconazole in lung transplant patients who received itraconazole for prophylaxis (n = 12) or therapy (n = 5). These patients also received concomitant antacid and H2 blocker therapy. In patients receiving itraconazole at 200 and 400 mg/day, the median concentrations in serum were 0.5 microgram/ml (range, < 0.05 to 2.7) and 3.5 micrograms/ml (< 0.5 to 14), respectively. The concentration following administration of 400 mg/day was > 2.5 micrograms/ml in 56% of samples, while only 4% of samples from patients who were administered 200 mg/day had levels over 2.5 micrograms/ml. This study documents that itraconazole can be absorbed in patients receiving concomitant antacid and H2 blocker therapy. However, the reduced and variable absorption suggests the importance of confirming drug delivery by measurement of concentrations in serum.

Evaluation of SCH51048 in an experimental model of pulmonary aspergillosis

The efficacy of a novel triazole, SCH51048, was assessed with a murine model of pulmonary aspergillosis and was compared with those of SCH39304 and itraconazole. A wide range of doses of SCH51048 (5 to 50 mg/kg of body weight) was evaluated. Mortality was significantly delayed in mice treated with doses of 5 mg of SCH51048 per kg or greater in comparison with mortality in controls (P < 0.05). Both SCH51048 and SCH39304 at higher doses (30 and 50 mg/kg) reduced the number of viable Aspergillus fumigatus organisms in lung tissue (P < 0.05). In the present model, itraconazole neither delayed mortality nor significantly reduced the counts in tissue at the doses used. We conclude that SCH51048 is an effective therapy for murine pulmonary aspergillosis.

Treatment of exogenous Candida endophthalmitis in rabbits with oral fluconazole

We investigated the efficacy of oral fluconazole, alone or in combination with oral flucytosine (5FC), in treating Candida endophthalmitis using a rabbit model. Albino rabbits were infected with an intravitreal inoculation of 1,000 CFU of susceptible Candida albicans and randomized 5 days later to receive treatment with oral fluconazole alone (80 mg/kg of body weight per day), a combination of fluconazole and 5FC (100 mg/kg/12 h), or no treatment. The treatment effect was assessed at 2 and 4 weeks after therapy by funduscopy, quantitative vitreous culture, and histopathology. Intravitreal levels of fluconazole, 2 to 24 h after the first dose, were measured to be > 10 times the MIC of the drug for C. albicans. Among rabbits treated with fluconazole for 2 weeks, 67% had a > 90% reduction in fungal load (P < 0.05) and 33% were sterile. After 4 weeks, all had a > 99% reduction in fungal load (P < 0.05) and 75% were sterile (P = 0.01). This treatment effect was unchanged 4 weeks after discontinuation of fluconazole. Among rabbits treated with fluconazole and 5FC for 2 weeks, 67% died during therapy. Among the surviving rabbits, 75% had a > 90% reduction in fungal load (P < 0.05) and 25% were sterile. We conclude that oral fluconazole may be useful for treatment of Candida endophthalmitis. Addition of 5FC was associated with high toxicity and minimal additional antifungal effect in our rabbit model.

Efficacy of itraconazole solution in a rabbit model of invasive aspergillosis

The efficacy of an itraconazole-cyclodextrin solution against Aspergillus fumigatus was assessed in an immunosuppressed, temporarily leukopenic rabbit model of invasive aspergillosis and compared with that of amphotericin B. Oral itraconazole solution at dosages of 20 and 40 mg/kg/day improved survival as compared with that of controls. Itraconazole (40 mg/kg/day) not only improved survival and reduced antigen levels but also significantly eradicated A. fumigatus from tissues and was as effective as amphotericin B in these studies. The higher dose of itraconazole produced higher levels in serum, which correlated with improved efficacy of the drug. This itraconazole-cyclodextrin solution was well absorbed and was effective in the treatment of experimental invasive aspergillosis; it demonstrates the potential of this class of agents in improving therapy for invasive aspergillosis.

Clinical pharmacokinetics of fluconazole

Fluconazole was recently developed for the treatment of superficial and systemic fungal infections. Triazole groups and insertion of 2 fluoride atoms increase the polarity and hydrosolubility of the drug, allowing it to be used in a parenteral form. Bioassay methods using Candida pseudotropicalis as a test organism were the first techniques used for the determination of fluconazole in body fluids. Gas chromatographic and high performance liquid chromatographic methods were later developed with better accuracy and sensitivity. Prediction of efficacious concentrations in patients from the minimum inhibitory concentrations in vitro seems to be uncertain because of low efficacy of the drug on some yeasts in vitro compared with efficacy in vivo in animal models. Oral forms (capsule and solution) are quickly absorbed and bioavailability is nearly complete (about 90%). Plasma protein binding is low (11 to 12%) and fluconazole circulates as active drug. Distribution is extensive throughout the tissues and allows the treatment of a variety of systemic fungal infections. The average elimination half-life (t1/2) of 31.6 +/- 4.9h is long, with a minimum of 6 days needed to reach steady-state; thus, a loading dose (equal to double the maintenance dose) is recommended. The metabolism of fluconazole is not qualitatively or quantitatively significant. The main route of elimination is renal. The mean +/- SD (calculated from published data) total and renal clearance values are 19.5 +/- 4.7 and 14.7 +/- 3.7 ml/min (1.17 +/- 0.28 and 0.88 +/- 0.22 L/h), respectively. Concentrations of fluconazole in blood after administration of single doses correlated well with the administered dose. There was very little interassay variation between the data reported in literature. Concentrations in blood after multiple doses also exhibit little variation and the accumulation factor was between 2.1 and 2.8. Fluconazole was found in many body fluids, especially in cerebrospinal fluid and dialysis fluid, allowing the treatment of systemic fungal infections such as coccidioidal meningitis and fungal peritonitis. Concentrations of 1 to 3 mg/L and 20 mg/L are the extreme values expected in clinical practice. In renal insufficiency the fluconazole t1/2 is longer, requiring dosage adjustment in relation to creatinine clearance. In continuous ambulatory peritoneal dialysis a 150mg dose in a 2L dialysis solution every 2 days has been proposed. In haemodialysis, a dose of 100 or 200mg should be given at the end of each dialysis session. Neither old age nor irradiation affect fluconazole pharmacokinetics, but the t1/2 was shorter in children.(ABSTRACT TRUNCATED AT 400 WORDS)

Standardization of a fluconazole bioassay and correlation of results with those obtained by high-pressure liquid chromatography

An improved bioassay for fluconazole was developed. This assay is sensitive in the clinically relevant range (2 to 40 micrograms/ml) and analyzes plasma, serum, and cerebrospinal fluid specimens; bioassay results correlate with results obtained by high-pressure liquid chromatography (HPLC). Bioassay and HPLC analyses of spiked plasma, serum, and cerebrospinal fluid samples (run as unknowns) gave good agreement with expected values. Analysis of specimens from patients gave equivalent results by both HPLC and bioassay. HPLC had a lower within-run coefficient of variation (less than 2.5% for HPLC versus less than 11% for bioassay) and a lower between-run coefficient of variation (less than 5% versus less than 12% for bioassay) and was more sensitive (lower limit of detection, 0.1 micrograms/ml [versus 2 micrograms/ml for bioassay]). The bioassay is, however, sufficiently accurate and sensitive for clinical specimens, and its relative simplicity, low sample volume requirement, and low equipment cost should make it the technique of choice for analysis of routine clinical specimens.

High-dose itraconazole in the treatment of severe mycoses

Eight patients with systemic mycoses and with prior treatment failures were treated with itraconazole (600 mg/day) for a mean duration of 5.5 months. All six patients without AIDS experienced improvement or stabilization of their fungal infections while receiving high-dose itraconazole, although two patients later experienced treatment failures, one by relapse and one by progression, on lower doses. Treatment failures also occurred in the two patients with AIDS and cryptococcal meningitis. The failures were associated with low serum itraconazole concentrations (less than 2.5 micrograms/ml) in both patients. All other patients had mean trough levels in serum above 5 micrograms/ml. One patient who was improving on 600 mg/day developed a progressive infection after reduction of the dose to 400 mg/day. Side effects included reversible adrenal insufficiency in one patient; severe hypokalemia, mild diastolic hypertension, and rhabdomyolysis in one patient; mild hypokalemia and hypertension in four other patients; and breast tenderness in one patient. The mean decrease in serum potassium during treatment was statistically significant (P = 0.05). Selected patients with severe systemic mycoses may benefit from prolonged high-dose itraconazole treatment. However, 600 mg/day may be approaching the upper limits of acceptable dosing for long-term treatment.

Combined therapy with fluconazole and flucytosine in murine cryptococcal meningitis

To assess the possible beneficial effects of combined therapy (fluconazole and flucytosine) in the treatment of cryptococcal meningitis in the immunocompromised host, we compared therapy with fluconazole and flucytosine, individually and combined, in the experimental murine model. BALB/c athymic (nu/nu) mice were infected intracerebrally with 150 to 300 CFU of Cryptococcus neoformans. In mortality studies, treatment was initiated 24 h postinfection and continued for 10 to 14 days with either fluconazole (1 to 15 mg/kg of body weight per day), flucytosine (60 to 120 mg/kg/8 h), both drugs, or 0.3% Noble agar (control). Combined therapy delayed mortality significantly when compared with controls and single-drug regimens. This was observed over a broad range of doses. Quantitative determinations of CFU in brain tissue demonstrated a significantly lower burden of C. neoformans in mice receiving combined therapy. The results indicate that combined therapy with fluconazole and flucytosine is superior to single-drug therapy.

Oral fluconazole therapy for patients with acquired immunodeficiency syndrome and cryptococcosis: experience with 22 patients

PURPOSE

Cryptococcus neoformans causes infections in up to 10 percent of patients with the acquired immunodeficiency syndrome (AIDS). Nearly 50 percent of AIDS patients with previously treated cryptococcal meningitis will experience a relapse within six months. To reduce the likelihood of relapse, a maintenance regimen of amphotericin B is often administered weekly. However, the drug's intravenous route of administration and considerable toxicity have led to a search for alternative antifungal agents. In this report, we document our experience with fluconazole, a new oral triazole antifungal agent.

PATIENTS AND METHODS

Twenty-two patients with AIDS and various forms of cryptococcosis were treated in an open-label study with 50 to 400 mg/day of fluconazole. The following laboratory studies were done on a monthly basis: complete blood cell count, liver function tests, serum creatinine level, serum cryptococcal antigen level, and serum fluconazole level. Lumbar puncture was performed in patients with meningitis every four to eight weeks to evaluate cerebrospinal fluid cryptococcal antigen, India ink preparation findings, fungal culture, fluconazole level, and protein, glucose, and cell count.

RESULTS

Of seven patients with active culture-positive infections, four showed clinical and microbiologic responses (three of four with meningitis, one of three with extraneural cryptococcosis). Fifteen patients who had already undergone successful amphotericin B therapy for either meningitis (n = 14) or pneumonia (n = 1) received fluconazole as prophylaxis against relapse. Fourteen patients remained free of infection during 11 to 64 weeks of suppressive therapy; one patient with meningitis experienced relapse after 26 weeks of treatment. Reverse reactions were limited to increases in hepatic enzyme levels in four patients.

CONCLUSION

These results appear sufficiently encouraging to warrant further trials of this oral agent in the suppression of chronic cryptococcosis and perhaps in the treatment of acute infection.

Treatment of systemic fungal infections: recent progress and current problems

Systemic mycoses continue to emerge as life-threatening infections. Considerable progress in treating these infections is being achieved through better application of established available antifungal agents (amphotericin B, flucytosine, miconazole and ketoconazole), and through development of promising investigational agents (fluconazole, itraconazole). Systemic fungal infections, however, continue to present major problems, including clinical resistance, microbiological resistance, emergence of new pathogens, and involvement of more immunocompromised patients. The purpose of this paper, therefore, is to review the recent progress and current problems in treatment of systemic fungal infections.

Intraperitoneal flucytosine in the management of fungal peritonitis in patients on continuous ambulatory peritoneal dialysis

Five episodes of fungal peritonitis were treated by intraperitoneal instillation of 5-flucytosine (5-Fc) while the patients remained on their usual schedule of dialysis. Therapeutic, nontoxic dialysate and serum concentrations of 5-Fc were achieved. Although some patients transiently responded with improved symptoms, a drop in their dialysate WBC count and negative cultures, all patients required removal of their dialysis catheters for cure. It is concluded that intraperitoneal (IP) 5-Fc, as used in this study, is not efficacious in the treatment of fungal peritonitis.

Activities of fluconazole (UK 49,858) and ketoconazole against ketoconazole-susceptible and -resistant Candida albicans

We have compared the activities of fluconazole and ketoconazole against ketoconazole-susceptible and -resistant strains of Candida albicans in a neutropenic-site rabbit model. Oral treatment with fluconazole resulted in much higher serum and extravascular concentrations of this antifungal agent than did comparable doses of ketoconazole. Fluconazole had no additional in vivo activity against the ketoconazole-susceptible strains; no fungicidal activity was observed with peak drug levels as high as approximately 75 micrograms/ml in the infection sites. Significant fungistatic activity against the ketoconazole-resistant strains was observed with fluconazole treatment (80 mg/kg), but not with less fluconazole (20 mg/kg) or with ketoconazole (approximately 67 mg/kg). In vitro susceptibility tests separated the ketoconazole-susceptible strains from the ketoconazole-resistant strains, but the results were variable when the resistant strains were tested with fluconazole.

Clinical pharmacokinetics of ketoconazole

Ketoconazole, a synthetic imidazole antifungal, is effective for superficial fungal infections, genital candidosis and chronic mucocutaneous candidosis, and has been used in immunocompromised patients and advanced prostatic carcinoma. Absorption of ketoconazole is variable after oral administration, with large variability in peak serum concentrations. Antacids reduce, and food or dilute hydrochloric acid increase, absorption. Renal failure and bone marrow transplantation are associated with reduced absorption. Ketoconazole is not absorbed systemically after topical administration, and minimally absorbed from the vagina. Distribution of ketoconazole varies according to the tissue sampled, the underlying disease and the dose and duration of treatment. Ketoconazole does not cross the intact blood-brain barrier, and crosses to only a limited extent in fungal meningitis. Urinary concentrations of ketoconazole are usually low, but vaginal and vaginal tissue concentrations correlate with those in serum. Seminal fluid concentrations are inadequate for treatment of epididymitis. Ketoconazole is 83.7% plasma protein (mainly albumin) bound, and 15.3% is erythrocyte bound, resulting in only 1% of free drug. Animal studies indicate strong binding to the cytochrome P-450 mono-oxygenase complex. Extensive metabolism to inactive metabolites occurs, the products being mainly excreted in the faeces. Saturable hepatic first-pass metabolism is probable. The half-life of ketoconazole is dose-dependent, increases during long term treatment, suggesting auto-inhibition of metabolism. The kinetics after oral administration fit a 2-compartment model. Drug interactions of theoretical, if not practical, significance include warfarin, chlordiazepoxide, methylprednisolone, cyclosporin and drugs known to induce microsomal enzymes. In each case, some dosage adjustment for ketoconazole, or the interacting drug, may be required.