RESUMO
Icofungipen (formerly PLD-118) is a synthetic derivative of the naturally occurring beta-amino acid cispentacin that blocks isoleucyl-tRNA synthetase, resulting in the inhibition of protein synthesis and growth of fungal cells. We investigated the efficacy, plasma pharmacokinetics, and safety of icofungipen in escalating dosages for the treatment of experimental subacute disseminated candidiasis in persistently neutropenic rabbits. Icofungipen was administered for 10 days starting 24 h after the intravenous inoculation of 10(3) Candida albicans blastoconidia. Study groups consisted of rabbits treated with icofungipen at 4 (ICO-4), 10 (ICO-10), and 25 (ICO-25) mg/kg of body weight/day in two divided dosages, rabbits treated with fluconazole at 10 mg/kg/day, rabbits treated with amphotericin B at 1 mg/kg/day, and untreated controls. Levels of icofungipen in plasma were derivatized by phthaldialdehyde and quantified by high-performance liquid chromatography with fluorescence detection. Rabbits treated with ICO-10 (P < 0.01) and ICO-25 (P < 0.001) showed significant dosage-dependent tissue clearance of C. albicans from the liver, spleen, kidney, brain, vitreous, vena cava, and lung in comparison to untreated controls. ICO-25 cleared C. albicans from all tissues and had activity comparable to that of amphotericin B versus untreated controls (P < 0.001). Pharmacokinetics of icofungipen in plasma approximated a dose-dependent relationship of the maximum concentration of drug in serum and the area under the concentration-time curve. There was no significant elevation of the levels of hepatic transaminases, alkaline phosphatase, bilirubin, urea nitrogen, or creatinine in icofungipen-treated rabbits. Icofungipen followed dose-dependent pharmacokinetics and was effective in the treatment of experimental disseminated candidiasis, including central nervous system infection, in persistently neutropenic rabbits.
Assuntos
Antifúngicos/farmacologia , Candida albicans/enzimologia , Candidíase/tratamento farmacológico , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Isoleucina-tRNA Ligase/antagonistas & inibidores , Neutropenia/complicações , Animais , Antifúngicos/efeitos adversos , Antifúngicos/farmacocinética , Candida albicans/efeitos dos fármacos , Candida albicans/ultraestrutura , Candidíase/microbiologia , Meios de Cultura , Cicloleucina/efeitos adversos , Cicloleucina/farmacocinética , Feminino , Terapia de Imunossupressão , Rim/microbiologia , Fígado/microbiologia , Coelhos , Baço/microbiologiaRESUMO
PLD-118, formerly BAY 10-8888, is a synthetic antifungal derivative of the naturally occurring beta-amino acid cispentacin. We studied the activity of PLD-118 in escalating dosages against experimental oropharyngeal and esophageal candidiasis (OPEC) caused by fluconazole (FLC)-resistant Candida albicans in immunocompromised rabbits. Infection was established by fluconazole-resistant (MIC > 64 microg/ml) clinical isolates from patients with refractory esophageal candidiasis. Antifungal therapy was administered for 7 days. Study groups consisted of untreated controls; animals receiving PLD-118 at 4, 10, 25, or 50 mg/kg of body weight/day via intravenous (i.v.) twice daily (BID) injections; animals receiving FLC at 2 mg/kg/day via i.v. BID injections; and animals receiving desoxycholate amphotericin B (DAMB) i.v. at 0.5 mg/kg/day. PLD-118- and DAMB-treated animals showed a significant dosage-dependent clearance of C. albicans from the tongue, oropharynx, and esophagus in comparison to untreated controls (P = 0.05, P = 0.01, P = 0.001, respectively), while FLC had no significant activity. PLD-118 demonstrated nonlinear plasma pharmacokinetics across the investigated dosage range, as was evident from a dose-dependent increase in plasma clearance and a dose-dependent decrease in the area under the plasma concentration-time curve. The biochemical safety profile was similar to that of FLC. In summary, PLD-118 demonstrated dosage-dependent antifungal activity and nonlinear plasma pharmacokinetics in treatment of experimental FLC-resistant oropharyngeal and esophageal candidiasis.
Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Candidíase/microbiologia , Cicloleucina/análogos & derivados , Cicloleucina/uso terapêutico , Inibidores Enzimáticos/farmacologia , Fluconazol/farmacologia , Isoleucina-tRNA Ligase/antagonistas & inibidores , Animais , Área Sob a Curva , Candida albicans/enzimologia , Candidíase Bucal/microbiologia , Cicloleucina/efeitos adversos , Cicloleucina/farmacocinética , Farmacorresistência Fúngica , Inibidores Enzimáticos/efeitos adversos , Inibidores Enzimáticos/farmacocinética , Doenças do Esôfago/microbiologia , Feminino , Meia-Vida , Terapia de Imunossupressão , CoelhosRESUMO
Invasive pulmonary aspergillosis (IPA) is a frequently fatal infection in immunocompromised patients that is difficult to diagnose. Present methods for detection of Aspergillus spp. in bronchoalveolar lavage (BAL) fluid and in tissue vary in sensitivity and specificity. We therefore developed an A. fumigatus-specific quantitative real-time PCR-based assay utilizing fluorescent resonance energy transfer (FRET) technology. We compared the assay to quantitative culture of BAL fluid and lung tissue in a rabbit model of experimental IPA. Using an enzymatic and high-speed mechanical cell wall disruption protocol, DNA was extracted from samples of BAL fluid and lung tissues from noninfected and A. fumigatus-infected rabbits. A unique primer set amplified internal transcribed spacer regions (ITS) 1 and 2 of the rRNA operon. Amplicon was detected using FRET probes targeting a unique region of ITS1. Quantitation of A. fumigatus DNA was achieved by use of external standards. The presence of PCR inhibitors was determined by use of a unique control plasmid. The analytical sensitivity of the assay was =10 copies of target DNA. No cross-reactivity occurred with other medically important filamentous fungi. The assay results correlated with pulmonary fungal burden as determined by quantitative culture (r = 0.72, Spearman rank correlation; P = 0.0001). The mean number of genome equivalents detected in untreated animals was 3.86 log(10) (range, 0.86 to 6.39 log(10)) in tissue. There was a 3.53-log(10) mean reduction of A. fumigatus genome equivalents in animals treated with amphotericin B (AMB) (95% confidence interval, 3.38 to 3.69 log(10); P = 0.0001), which correlated with the reduction of residual fungal burden in lung tissue measured in terms of log(10) CFU/gram. The enhanced quantitative sensitivity of the real-time PCR assay was evidenced by detection of A. fumigatus genome in infarcted culture-negative lobes, by a greater number of mean genome equivalents compared to the number of CFU per gram in tissue and BAL fluid, and by superior detection of therapeutic response to AMB in BAL fluid compared to culture. This real-time PCR assay using FRET technology is highly sensitive and specific in detecting A. fumigatus DNA from BAL fluid and lung tissue in experimental IPA.
Assuntos
Aspergilose Broncopulmonar Alérgica/microbiologia , Aspergillus fumigatus , Aspergillus fumigatus/genética , Aspergillus fumigatus/isolamento & purificação , Sequência de Bases , Líquido da Lavagem Broncoalveolar/microbiologia , Primers do DNA , DNA Fúngico/genética , DNA Ribossômico/genética , Transferência Ressonante de Energia de Fluorescência/métodos , Humanos , Sondas de Oligonucleotídeos , Reação em Cadeia da Polimerase/métodos , Análise de Regressão , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Invasive pulmonary aspergillosis is an important cause of morbidity and mortality in immunocompromised patients. Simultaneous inhibition of fungal cell-wall and cell-membrane biosynthesis may result in synergistic interaction against Aspergillus fumigatus. We studied the antifungal activity of micafungin, a new echinocandin, in combination with ravuconazole, a second-generation triazole, against experimental invasive pulmonary aspergillosis in persistently neutropenic rabbits. This combination led to significant reductions in mortality (P=.001), residual fungal burden (P=.05), and serum galactomannan antigenemia (P=.01), compared with either agent alone. Combination therapy also resulted in reduction (P=.05) of organism-mediated pulmonary injury and of pulmonary infiltrates detected by thoracic computed tomography (P=.001). No toxicity was observed with the echinocandin-triazole combination. An MTT hyphal damage assay demonstrated significant in vitro synergistic interaction between the antifungal triazole and the echinocandin. The combination of an antifungal triazole and echinocandin may represent a new strategy for treatment of invasive pulmonary aspergillosis.