SCH 56592 (posaconazole), a new triazole antifungal agent, was tested in vitro, and its activity was compared to that of itraconazole against 39 Aspergillus strains and to that of fluconazole against 275 Candida and 9 Cryptococcus strains. The SCH 56592 MICs for Aspergillus ranged from <0.002 to 0.5 g/ml, and those of itraconazole ranged from <0.008 to 1 g/ml. The SCH 56592 MICs for Candida and Cryptococcus strains ranged from <0.004 to 16 g/ml, and those of fluconazole ranged from <0.062 to >64 g/ml. SCH 56592 showed excellent activity against Aspergillus fumigatus and Aspergillus flavus in a pulmonary mouse infection model. When administered therapeutically, the 50% protective doses (PD 50 s) of SCH 56592 ranged from 3.6 to 29.9 mg/kg of body weight, while the PD 50 s of SCH 56592 administered prophylactically ranged from 0.9 to 9.0 mg/kg; itraconazole administered prophylactically was ineffective (PD 50 s, >75 mg/kg). SCH 56592 was also very efficacious against fluconazole-susceptible, -susceptible dose-dependent, or -resistant Candida albicans strains in immunocompetent or immunocompromised mouse models of systemic infection. The PD 50 s of SCH 56592 administered therapeutically ranged from 0.04 to 15.6 mg/kg, while the PD 50 s of SCH 56592 administered prophylactically ranged from 1.5 to 19.4 mg/kg. SCH 56592 has excellent potential for therapy against serious Aspergillus or Candida infections.Of the estimated 100,000 known species of fungi, only about 180 have been shown to cause disease in humans, and only about 10% of these are encountered in most clinical settings (8). However, fungal infections have substantially increased over the past two decades, and invasive forms are important causes of morbidity and mortality (2, 16). The major increase in fungal infections is related to increased numbers of immunocompromised patients including those with human immunodeficiency virus infection-AIDS or cancer and bone marrow or solid organ transplant recipients, who are at risk of developing invasive fungal infections (5,7,12,16). Disseminated candidiasis, pulmonary aspergillosis, and mycoses caused by emerging opportunistic fungi are the most common of these serious mycoses (7,16,38). As a result, there is a developing consensus that prophylactic therapy should be used for these high-risk patients (12). Fluconazole (FLC) is used for prevention of fungal infections in some of these patients, but it is not active against Aspergillus or other filamentous fungi. However, there is great concern about the development of resistant Candida due to prophylactic use of FLC (4,10,15,18,23,35,37). Clearly, alternative antifungal agents are needed for both therapeutic and prophylactic use. SCH 56592 (SCH; posaconazole) is a new triazole antifungal agent with broad-spectrum activity against fungi including strains of Aspergillus and Candida resistant to FLC (9,11,19,24,30,33). This report describes the in vitro activity of SCH against Aspergillus and Candida and its efficacy in clinically relevant experimental infection models ...

Posaconazole and/or amphotericin B was given to mice pretreated with a steroid and then infected by inhalation of Aspergillus flavus conidia. Two laboratories conducted studies using almost identical protocols to evaluate both survival and lung tissue burdens 8 days after infection. The results of the in vivo studies performed at both laboratories were consistent. We found that (i) up to 5 mg of amphotericin B per kg of body weight was poorly effective in treating invasive aspergillosis; (ii) posaconazole at 2 or 10 mg/kg/dose prolonged survival and reduced lung tissue CFU; and (iii) there was generally no antagonistic interaction of the drugs in combination, even when the experiments were designed to maximize the likelihood of antagonism. These studies do not confirm the antagonistic interaction of triazoles and polyenes reported by others.Acute invasive aspergillosis (AIA) is one of the most feared infections of immunosuppressed patients. Both corticosteroids and neutropenia predispose to this infection, which almost invariably occurs after inhalation of infectious conidia (1). The speed of dissemination or pulmonary spread of the infection, and ultimately survival, depend in large part on the nature and severity of the predisposing host immune defect(s). In patients with the most fulminating forms of AIA, it has been difficult to demonstrate efficacy of antifungal therapy (7, 11). To date, there have been three approaches in the management of aspergillosis. The first is reversal of the predisposing conditions if possible. The second is antifungal therapy, and the third is resection when possible (18). Animal studies have been increasingly used to help determine whether a particular antifungal drug is effective against invasive aspergillosis. Some advantages of animal studies include (i) information in ascertaining the relative efficacy and dose-dependent toxicity of antifungal agents; (ii) assessing the contributions of immune deficiency to the outcome of aspergillosis; (iii) evaluating combinations of antifungals; and (iv) controlling for a variety of conditions that are thought to contribute to human invasive aspergillosis and its outcome but that cannot be controlled in clinical studies.The experiment quoted most often, an experiment using amphotericin B and ketoconazole, was conducted by Schaffner and Frick (15) some years ago. When mice with AIA were treated with ketoconazole before amphotericin B, Schaffner and Frick noted a marked decrease in the efficacy of amphotericin B (15). They theorized that the azole blocked the synthesis of the ergosterol target necessary for the binding of amphotericin B. Polak et al. also found somewhat similar results (13,14). These studies led to the concern that azole antifungal agents would antagonize the effects of amphotericin B in humans and that therefore they should not be used in combination with amphotericin B clinically.In a large review of 595 cases of aspergillosis, Patterson et al. found that patients treated with amphotericin B and then with itraconazole fare...

The interaction of posaconazole and amphotericin B was evaluated in concomitant treatment of Candida albicans systemic infections in immunocompetent mice by using four strains of C. albicans with different susceptibilities to fluconazole. Posaconazole and amphotericin B were each tested at four dose levels alone and in all possible combinations against each C. albicans strain. Survival curves of mice treated with combinations of posaconazole and amphotericin B were statistically compared with those of mice treated with the component monotherapies. Of the 64 total combinations evaluated against the C. albicans strains (16 combinations per strain), 20.3% were more effective in prolonging mouse survival than both of the monotherapies, 45.3% were more effective than one of the monotherapies, and 32.8% were similar to both monotherapies. No evidence of antagonism was observed between posaconazole and amphotericin B in this mouse model, consistent with in vitro results against the same strains.The clinical use of azoles in combination with amphotericin B (AMB) is still controversial because of the potential for antagonism between the two drugs (9,12,18,22). This potential comes from their mechanisms of action; azoles block ergosterol biosynthesis, while AMB causes membrane damage by binding to ergosterol. Various experimental fungal infection models have been used to address the issue of combinational dosing, but the results have been mixed. In systemic candidiasis models in mice with Candida albicans, Louie et al. (11) observed antagonism between the triazole fluconazole (FLC) and AMB, while Sugar and Liu (23) reported antagonism between another triazole, itraconazole, and AMB. Louie et al. (10,12) also found that FLC was antagonistic to AMB therapy against experimental C. albicans endocarditis, endophathalmitis, and pyelonephritis in rabbits. However, Sanati et al. (17) did not observe antagonism when FLC and AMB were used in combination against C. albicans in invasive candidiasis in neutropenic mice or in endocarditis in rabbits. Sugar et al. (21) reported no antagonism between FLC and AMB in invasive candidiasis with C. albicans in immunocompetent or immunocompromised mice.Posaconazole (POS) is a broad-spectrum antifungal triazole which recently completed phase III clinical trials (7). The experiments described in this report were performed to determine the interaction between POS and AMB in concomitant combination therapy against systemic C. albicans infection in mice.( MATERIALS AND METHODSAntifungal agents. POS clinical oral suspension was used in these experiments, and dilutions were made in sterile water for injection. AMB (Fungizone) was obtained from Apothecon, Bristol-Myers Squibb, Princeton, N.J., and prepared according to the manufacturer's directions.C. albicans strains and in vitro activity testing. All C. albicans strains were from the Schering-Plough Research Institute fungal culture collection and included one FLC-susceptible (FLC-S) strain C43, one FLC-susceptible, dosedependent (FLC S-DD) strai...

The interaction of posaconazole and caspofungin was evaluated in concomitant treatment of Aspergillus fumigatus (two strains) or A. flavus (one strain) systemic infections in immunocompetent mice. Survival curves for mice treated with the combinations were compared statistically with those for mice treated with the component monotherapies. No antagonism was observed.Invasive aspergillosis continues to be a serious threat to immunocompromised patients, resulting in very significant mortality (2, 8) despite antifungal therapy (15). Outcomes could potentially be improved through the use of combination antifungal therapy (13,14).Combination treatment using antifungal agents with different mechanisms of action could potentially be synergistic against serious fungal infections. Posaconazole (POS) is a broad-spectrum antifungal triazole which recently completed phase III clinical trials (6). POS, like other triazoles, inhibits 14-demethylase activity, resulting in inhibition of the synthesis of ergosterol, a key component of fungal cell membranes. Caspofungin (CSP), an echinocandin, inhibits the synthesis of 1,3-beta-D-glucan, thereby interfering with cell wall synthesis (1). The different mechanisms of action of POS and CSP suggest that they may be complementary when used in combination. In this report, we examine the interaction between POS and CSP in combination therapy against systemic Aspergillus infections in mice.Aspergillus fumigatus ND158 and ND231 and A. flavus ND83 were obtained from the Schering-Plough Research Institute culture collection. The minimum effective concentration (MEC) end points for CSP were described by Arikan et al. (4). MICs for POS and CSP were determined and end points read according to CLSI methodology (M38-A) (10). Drug interactions between POS and CSP were determined by a checkerboard microdilution MIC method. Preparation of the inoculum, drug dilutions, and reading of end points for drug interaction tests were performed as described in document M38-A. The drug interaction studies were scored by using the azole end point (100% inhibition of growth) and, consequently, were primarily a measure of the impact of CSP on the POS MIC. The fractional inhibitory concentration (FIC) index (5) was defined as synergistic if the FIC was Յ0.5, indifferent if the FIC was Ͼ0.5 but Յ4, and antagonistic if the FIC was Ͼ4.For infection studies, A. fumigatus ND158 and ND231 were grown on Sabouraud dextrose agar slants and A. flavus ND83 was grown on malt extract agar slants for 7 days at 28°C. The conidia were washed off the slants and used to inoculate tissue culture flasks containing malt extract agar, which were incubated for 7 to 8 days at 28°C. Conidia from four flasks were suspended and diluted 1:5 in saline, and this suspension was used for infection of immunocompetent mice on day 0 by intravenous injection of 0.1 ml into the tail vein. Inocula (CFU/ mouse), determined by plate counts on Sabouraud dextrose agar, were 1.5 ϫ 10 6 and 9.5 ϫ 10 6 for ND158, 1.9 ϫ 10 6 , 4.4 ϫ 10 6 , and 4.9 ϫ 10 6 for ...

The nonionic detergent, Pluronic L-81 (L-81) has been shown to block the transport of intestinal mucosal triacylglycerol (TG) in chylomicrons. This results in large lipid masses within the enterocyte that are greater in diameter than chylomicrons. On removal of L-81, mucosal TG is rapidly mobilized and appears in the lymph. We questioned whether the blocked TG requires partial or complete hydrolysis before its transport.Rats were infused intraduodenally with 13H]glyceryl, ["4Cj-oleoyl trioleate (TO) and 0.5 mg L-81/h for 8 h, followed by 120 ,mol/h linoleate for 18 h. Mesenteric lymph was collected and analyzed for TG content and radioactivity. An HPLC method was developed to separate TG on the basis of its acyl group species. The assumed acyl group composition was confirmed by gas liquid chromatography analysis. TG lymphatic output was low for the first 8 h but increased to 52 Mmol/h at the 11th h of infusion (3 h after stopping L-81). 38% of the infused TO was retained in the mucosa after the 8-h infusion. 95% of mucosal TG was TO, 92% of the radioactivity was in TG, and 2.4% of the '4C disintegrations per minute was in fatty acid. HPLC analysis of lymph at 6, 10, 12, and 14.5 h of infusion showed a progressive rise in TG composed of one linoleate and two oleates, to 39%; and in TG composed of two linoleates and one oleate to 20% at 14.5 h of infusion. On a mass basis, however, 80% of the TG acyl groups were oleate.3H/"4C ratios in the various TG acyl group species reflected the decrease in oleate. We conclude that first, unlike liver, most mucosal TG is not hydrolyzed before transport. The mechanism of how the large lipid masses present in mucosal cells after L-81 infusion are converted to the much smaller chylomicrons is unknown. Second, the concomitant infusion of linoleate did not impair lymph TG delivery after L-81 blockade.