Oral antifungals as prophylaxis in haematological malignancy

Intraocular penetration of itraconazole in patient with fungal endophthalmitis

The purpose of this study was to determine the penetration of itraconazole, a type of azole antifungal agent, into the aqueous humor and vitreous after repeated oral administrations. Fungal endophthalmitis developed bilaterally in a 21-year-old man who had a history of intravenous hyperalimentation following abdominal surgery. Itraconazole capsules (200 mg/day) were taken orally for 12 consecutive days. Vitrectomy was performed on the left eye 30 h after the last oral itraconazole. Samples of blood, aqueous, and vitreous were collected during the vitrectomy. The concentration of itraconazole was determined by high performance liquid chromatography. The concentration of itraconazole was 0.492 μg/mL in the plasma, 0.020 μg/mL in the vitreous, and none in the aqueous of the left eye. Although no fungal organisms were isolated from the plasma and vitreous samples from both eyes, fungal DNA was detected in the vitreous from the left eye. Our findings indicate that oral itraconazole has limited penetration in eyes with fungal endophthalmitis.

Correlation of in vitro activity and in vivo efficacy of itraconazole intravenous and oral solubilized formulations by testing Candida strains with various itraconazole susceptibilities in a murine invasive infection

OBJECTIVES

To examine whether in vitro antifungal susceptibility test results correlate with in vivo efficacy of two cyclodextrin-solubilized itraconazole formulations (intravenous and oral) against Candida in a murine model of invasive infection.

METHODS

A selected set of 12 Candida spp. strains with various itraconazole susceptibilities were tested. We studied the efficacy of intravenous and oral itraconazole administered once daily at dosages of 0.63, 2.5, 10 and 40 mg/kg body weight in mice lethally infected with each tested strain. Survival of mice in each treated group was monitored daily until the death of all control mice and compared between groups.

RESULTS

Survival of mice infected with 9 of 12 Candida strains with itraconazole MICs of ≤0.016-2.0 mg/L was significantly prolonged by treatment with intravenous itraconazole at dosages of 2.5 or 10 mg/kg and above. In contrast, the other three strains resistant to 8 mg/L itraconazole in vitro were refractory to the therapy, even at the highest itraconazole dosage (40 mg/kg). Closely similar in vivo data were obtained with the oral itraconazole therapy. The effective doses of the two itraconazole formulations increased with increasing itraconazole MICs for the infecting strains.

CONCLUSIONS

The in vivo efficacy of intravenous and oral itraconazole correlated with the in vitro susceptibility data.

Human pharmacogenomic variations and their implications for antifungal efficacy

Pharmacogenomics is defined as the study of the impacts of heritable traits on pharmacology and toxicology. Candidate genes with potential pharmacogenomic importance include drug transporters involved in absorption and excretion, phase I enzymes (e.g., cytochrome P450-dependent mixed-function oxidases) and phase II enzymes (e.g., glucuronosyltransferases) contributing to metabolism, and those molecules (e.g., albumin, A1-acid glycoprotein, and lipoproteins) involved in the distribution of antifungal compounds. By using the tools of population genetics to define interindividual differences in drug absorption, distribution, metabolism, and excretion, pharmacogenomic models for genetic variations in antifungal pharmacokinetics can be derived. Pharmacogenomic factors may become especially important in the treatment of immunocompromised patients or those with persistent or refractory mycoses that cannot be explained by elevated MICs and where rational dosage optimization of the antifungal agent may be particularly critical. Pharmacogenomics has the potential to shift the paradigm of therapy and to improve the selection of antifungal compounds and adjustment of dosage based upon individual variations in drug absorption, metabolism, and excretion.

Central venous catheter-related infection due to Candida membranaefaciens, a new opportunistic azole-resistant yeast in a cancer patient: a case report and a review of literature

An unusual central venous catheter (CVC)-related infection caused by Candida membranaefaciens in a patient with non-Hodgkin's lymphoma is described. Clinical signs and microbiological results observed in this case may support the hypothesis of an emerging CVC-related fungaemia, because of new azole-resistant yeast, successfully treated with liposomal amphotericin B. To date C. membranaefaciens (the teleomorph of Pichia membranaefaciens) has traditionally been considered non-pathogenic and this report seems to be the first case of systemic fungal infection. We believe that another fungus can be added to the list of opportunistic strains.

Risk factors of invasive aspergillosis after heart transplantation: protective role of oral itraconazole prophylaxis

The study was designed to identify a subset of heart transplant (HT) recipients who could benefit from the administration of targeted antifungal prophylaxis and to evaluate the efficacy of oral itraconazole as the preventive drug. We have analyzed the risk factors for invasive aspergillosis (IA) in our entire population of HT recipients (1988-2002) and also the role of oral itraconazole prophylaxis that was provided to all patients since 1995 [400 mg q.d. of itraconazole oral (PO) for 3-6 months]. There were 24 cases of IA. Our main results indicate that the independent risk factors for IA after heart transplantation are: re-operation (RR 5.8; 95% CI 1.8-18, p=0.002), cytomegalovirus (CMV) disease (RR 5.2; 95% CI 2-13.9, p=0.001), post-transplant hemodialysis (RR 4.9; 95% CI 1.2-18, p=0.02), and the existence of an episode of IA in the HT program 2 months before or after the transplantation date (RR 4.6; 95% CI 1.5-14.4, p=0.007). Itraconazole prophylaxis showed an independent protective value against developing IA (RR 0.2; 95% CI 0.07-0.9, p=0.03) and also determined a significantly prolonged 1-year survival (RR 0.5; 95% CI 0.3-0.8, p=0.01). We believe that antifungal prophylaxis in heart transplant patients should be offered at least to patients with one or more of these predisposing conditions.

Effect of interleukin 6 on the hepatic metabolism of itraconazole and its metabolite hydroxyitraconazole using primary human hepatocytes

A potential cytokine-drug interaction between interleukin 6 (IL-6) and itraconazole (ITZ) was studied using human hepatocytes in primary culture. Cultures from 5 adult males (mean age 42 +/- 15 years) who had not received any medicines known to interact with CYP3A4 were studied. Cultures were exposed to ITZ 500 ng/ml, and the effects of 120 microg/ml cimetidine, 50 ng/ml human IL-6, or IL-6 plus IL-6 receptor antagonist were analyzed for 2, 4, 8, and 12 h. Intracellular ITZ and hydroxyitraconazole concentrations were measured using HPLC and normalized to total cellular protein. Mean intracellular concentrations between groups were compared using one-way Anova (f test; p < 0.10) and corresponding Bonferroni versus control test for multiple comparisons (p < 0.02). Mean intracellular ITZ concentrations between the groups were similar at all time points. Human hepatocytes in primary culture can metabolize ITZ. However, IL-6 did not inhibit hydroxyitraconazole formation, but it may inhibit its subsequent metabolism.

Randomized trial of fluconazole versus low-dose amphotericin B in prophylaxis against fungal infections in patients undergoing hematopoietic stem cell transplantation

Over the past decade, invasive fungal infections have become an increasingly important problem in patients undergoing hematopoietic stem cell transplantation (HSCT). The optimal approach for prophylactic antifungal therapy has yet to be determined. To resolve this issue, we performed a prospective randomized study to compare the efficacy of fluconazole (FL) versus low-dose amphotericin B (AmB) in preventing fungal infections during the first 100 days after HSCT. Patients undergoing allogenic or autologous HSCT were randomized to receive fluconazole 200 mg/day PO or amphotericin B 0.2 mg/kg/day IV beginning 1 day prior to commencement of conditioning regimen and continuing until engraftment, drug-associated toxicity was suspected, or systemic fungal infection was suspected or proven. High-dose amphotericin B (0.5-1.0 mg/kg/day) was started for patients with suspected or proven fungal infections. From January 1993 to December 1998, a total of 186 patients were enrolled into the trial, with 100 receiving FL and 86 receiving AmB. Eighty (43%) patients were removed from prophylaxis for persistent fever despite broad-spectrum antibacterial therapy or suspected fungal infections (FL 46 vs. AmB 34, P > 0.05). The incidence of proven fungal infections (FL 12% vs. AmB 12.8%), suspected fungal infections (FL 4% vs. AmB 2.3%), superficial fungal infections (FL 1% vs. AmB 4.6%) did not show any significant difference. The survival at 100 days post transplant was similar between the 2 groups (FL 78% vs. AmB 70%, P = 0.254). Death attributable to fungal infections was similar in both groups (6% vs. 7%, P > 0.05). We conclude that fluconazole is as effective as low-dose amphotericin B in prophylaxis against fungal infections in patients undergoing hematopoietic cell transplantation.

Itraconazole preexposure attenuates the efficacy of subsequent amphotericin B therapy in a murine model of acute invasive pulmonary aspergillosis

Antagonism has been described in vitro and in vivo for azole-polyene combinations against Aspergillus species. Using an established murine model of invasive pulmonary aspergillosis, we evaluated the efficacy of several amphotericin B (AMB) dosages given alone or following preexposure to itraconazole (ITC). Mice were immunosuppressed with cortisone acetate and cyclophosphamide. During immunosuppression, animals were administered either ITC solution (50 mg/kg of body weight) or saline by oral gavage twice daily for 3 days prior to infection. Infection was induced by intranasally inoculating mice with a standardized conidial suspension (1 x 10(8) CFU/ml) of Aspergillus fumigatus strain AF 293. AMB was then administered by daily intraperitoneal injections (0.25, 0.5, 1.0, and 3.0 mg/kg) starting 24 h after inoculation and continuing for a total of 72 h. Drug pharmacokinetics of AMB and ITC in plasma were determined by high-performance liquid chromatography. Four different endpoints were used to examine the efficacy of antifungal therapy: (i) viable counts from harvested lung tissue (in CFU per milliliter), (ii) the whole-lung chitin assay, (iii) mortality at 96 h, and (iv) histopathology of representative lung sections. At AMB doses of >0.5 mg/kg/day, fewer ITC-preexposed mice versus non-ITC-preexposed mice were alive at 96 h (0 to 20 versus 60%, respectively). At all time points, the fungal lung burden was consistently and significantly higher in animals preexposed to ITC, as measured by the CFU counts (P = 0.001) and the chitin assay (P = 0.03). Higher doses of AMB did not overcome this antagonism. ITC preexposure was associated with poorer mycological efficacy and survival in mice treated subsequently with AMB for invasive pulmonary aspergillosis.