Early Pharmacokinetic and Clinical Results from a Noncomparative Multicentre Trial of Amphotericin B Encapsulated in a Small Unilamellar Liposome (AmBisome®)

The Combination Treatment of Fosmanogepix and Liposomal Amphotericin B Is Superior to Monotherapy in Treating Experimental Invasive Mold Infections

Invasive pulmonary aspergillosis (IPA), invasive mucormycosis (IM), and invasive fusariosis (IF) are associated with high mortality and morbidity. Fosmanogepix (FMGX) is a first-in-class antifungal in clinical development with demonstrated broad-spectrum activity in animal models of infections. We sought to evaluate the benefit of combination therapy of FMGX plus liposomal amphotericin B (L-AMB) in severe delayed-treatment models of murine IPA, IM, and IF. While FMGX was equally as effective as L-AMB in prolonging the survival of mice infected with IPA, IM, or IF, combination therapy was superior to monotherapy in all three models. These findings were validated by greater reductions in the tissue fungal burdens (determined by quantitative PCR) of target organs in all three models versus the burdens in infected vehicle-treated (placebo) or monotherapy-treated mice. In general, histopathological examination of target organs corroborated the findings for fungal tissue burdens among all treatment arms. Our results show that treatment with the combination of FMGX plus L-AMB demonstrated high survival rates and fungal burden reductions in severe animal models of invasive mold infections, at drug exposures in mice similar to those achieved clinically. These encouraging results warrant further investigation of the FMGX-plus-L-AMB combination treatment for severely ill patients with IPA, IM, and IF.

Sixty years of Amphotericin B: An Overview of the Main Antifungal Agent Used to Treat Invasive Fungal Infections

Introduced in the late 1950s, polyenes represent the oldest family of antifungal drugs. The discovery of amphotericin B and its therapeutic uses is considered one of the most important scientific milestones of the twentieth century . Despite its toxic potential, it remains useful in the treatment of invasive fungal diseases owing to its broad spectrum of activity, low resistance rate, and excellent clinical and pharmacological action. The well-reported and defined toxicity of the conventional drug has meant that much attention has been paid to the development of new products that could minimize this effect. As a result, lipid-based formulations of amphotericin B have emerged and, even keeping the active principle in common, present distinct characteristics that may influence therapeutic results. This study presents an overview of the pharmacological properties of the different formulations for systemic use of amphotericin B available for the treatment of invasive fungal infections, highlighting the characteristics related to their chemical, pharmacokinetic structures, drug–target interactions, stability, and others, and points out the most relevant aspects for clinical practice.

Development and characterization of oral liposomes of vegetal ceramide based amphotericin B having enhanced dry solubility and solubility

Despite the development of new antifungal, amphotericin B remains one of the most effective agents in the treatment of systemic fungal infections. Many patients exhibit nevertheless intolerance to amphotericin B at higher dosages and parenteral formulations present unlike per os ones, associated risks and high care cost. Free amphotericin B per os showed however an apparently poor absorption. In this study, we evaluate the potential of amphotericin B liposomes formulated with vegetal ceramides for oral administration. Ceramides, one of the constituents of cellular cytoplasmic membranes, constitute an important element in the construction and stability of their lipid bilayer. To fulfill this objective, vegetal ceramides, composed essentially of glucosylceramides, were firstly incorporated in various liposome preparations, entrapping or not amphotericin B, in comparison with phosphatidylcholine liposomes. Then, these preparations were introduced in an "Artificial-Stomach-Duodenum" model to improve their stability for oral administration. The formulation of amphotericin B liposomes containing ceramides presented a mean hydrodynamic size of about 200nm. We showed also that cholesterol and phospholipids are required to prevent drug leakage and to obtain lamellar structure respectively. In "Artificial-Stomach-Duodenum" model, ceramides conferred to liposomes better membrane stability. In addition, ceramides did not alter their drug encapsulation yield being by 75%. This could be explained by the fact that ceramides as we proved, limited the detergent effect of bile salts on liposome membranes.

Liposomal amphotericin B (AmBisome�) efficacy in confirmed invasive aspergillosis and other filamentous fungal infections in immunocompromised hosts: a pooled analysis

A pooled efficacy analysis applying current diagnostic standards for case selection was performed on previously published trials of liposomal amphotericin B for invasive filamentous fungal infections (IFFI). Favourable responses were observed in 51% of microbiologically confirmed cases of proven or probable IFFI. Despite the limitations inherent in a retrospective analysis of pooled studies, the response rates observed in this analysis were consistent with previous reports for antifungal therapy with amphotericin B deoxycholate or voriconazole in the treatment of invasive aspergillosis.

Liposomal amphotericin B as initial therapy for invasive mold infection: a randomized trial comparing a high-loading dose regimen with standard dosing (AmBiLoad trial)

BACKGROUND

Treatment of invasive mold infection in immunocompromised patients remains challenging. Voriconazole has been shown to have efficacy and survival benefits over amphotericin B deoxycholate, but its utility is limited by drug interactions. Liposomal amphotericin B achieves maximum plasma levels at a dosage of 10 mg/kg per day, but clinical efficacy data for higher doses are lacking.

METHODS

In a double-blind trial, patients with proven or probable invasive mold infection were randomized to receive liposomal amphotericin B at either 3 or 10 mg/kg per day for 14 days, followed by 3 mg/kg per day. The primary end point was favorable (i.e., complete or partial) response at the end of study drug treatment. Survival and safety outcomes were also evaluated.

RESULTS

Of 201 patients with confirmed invasive mold infection, 107 received the 3-mg/kg daily dose, and 94 received the 10-mg/kg daily dose. Invasive aspergillosis accounted for 97% of cases. Hematological malignancies were present in 93% of patients, and 73% of patients were neutropenic at baseline. A favorable response was achieved in 50% and 46% of patients in the 3- and 10-mg/kg groups, respectively (difference, 4%; 95% confidence interval, -10% to 18%; P>.05); the respective survival rates at 12 weeks were 72% and 59% (difference, 13%; 95% confidence interval, -0.2% to 26%; P>.05). Significantly higher rates of nephrotoxicity and hypokalemia were seen in the high-dose group.

CONCLUSIONS

In highly immunocompromised patients, the effectiveness of 3 mg/kg of liposomal amphotericin B per day as first-line therapy for invasive aspergillosis is demonstrated, with a response rate of 50% and a 12-week survival rate of 72%. The regimen of 10 mg/kg per day demonstrated no additional benefit and higher rates of nephrotoxicity.

Atualização no uso de agentes antifúngicos

Aborda-se sumariamente o espectro de ação, aspectos farmacológicos e toxicológicos e eficácia clínica de anfotericina B lipossomal, anfotericina B em dispersão coloidal, complexo lipídico de anfotericina B, voriconazol e caspofungina. Discute-se o uso desses antifúngicos mais recentes considerando a segurança, a eficiência e o custo da terapia. Sugestões para o uso clínico dessas drogas em infecções pulmonares e sistêmicas são apresentadas, destacando-se a menor toxicidade das formulações lipídicas da anfotericina B em relação à medicação convencional, a possibilidade de terapia primária da aspergilose invasiva, scedosporiose e fusariose com voriconazol e a caspofungina como opção terapêutica na candidíase disseminada e na aspergilose invasiva.

Amphotericin B: time for a new "gold standard"

When introduced in 1959, amphotericin B deoxycholate (AmBD) was clearly a life-saving drug. Randomized studies demonstrating its efficacy were not thought to be necessary, and it was granted indications for many invasive fungal infections. Despite its formidable toxicities, AmBD is thus often used as the primary comparator in studies of invasive fungal infections. Safer lipid-based versions of amphotericin B (AmB) have been introduced, but difficulties with studying these agents generally led to licensure for salvage therapy, not primary therapy. However, the cumulative clinical experience to date with the lipid-based preparations is now adequate to demonstrate that these agents are no less active than AmBD, and, for some infections, it can now be stated that specific lipid-based preparations of AmB are superior to AmBD. Given their superior safety profiles, these preparations can now be considered suitable replacements for AmBD for primary therapy for many invasive fungal infections in clinical practice and research.

Review of comparative studies between conventional and liposomal amphotericin B (Ambisome) in neutropenic patients with fever of unknown origin and patients with systemic mycosis

Fungal infections are an important cause of morbidity and mortality in immunocompromised patients. Treatment with amphotericin B is the main therapeutic approach. However, this treatment is limited by the substantial toxicity. We present the data of the first randomized prospective comparative trial in adults (134 patients with fever of unknown origin) with conventional amphotericin B and a liposomal formulation of amphotericin B (AmBisome, published in 1997 by Prentice et al. (Br. J. Haematol. 98, 711-718) and the data of adults with documented fungal infections (59 patients), treated in this trial. Patients received either conventional amphotericin B 1 mg kg-1 per day, liposomal amphotericin B 1 mg kg-1 per day or liposomal amphotericin B 3 mg kg-1 per day. Patients were entered if they had fever of unknown origin (FUO), defined as temperature of 38 degrees C or more, not responding to 96 h of systemic broad-spectrum antibiotic treatment, and neutropenia (< 0.5 x 10(9) l-1). Efficacy of treatment was assessed, with success defined as resolution of fever for three consecutive days (< 38 degrees C) in the group of patients with FUO and the freedom of clinical signs and/or the elimination of fungus in the group of patients with documented fungal infections. The safety of treatment and renal and hepatic toxicity of liposomal and conventional amphotericin B were compared. No statistically significant difference was found in the treatment efficacy in the three study arms. However, there is a tendency of better treatment results in the two groups of patients, who received liposomal amphotericin B. Thirty-five per cent of patients with documented fungal infections and 46% of patients with FUO responded to amphotericin B. In the patients group, that received 1 mg kg-1 liposomal amphotericin B it was 63 and 49%, in the group of patients that received 3 mg kg-1 liposomal amphotericin B it was 47 and 64%. Evidence of toxicity due to amphotericin B was seen in 50 patients (83%), toxicity due to liposomal amphotericin B, 1 mg kg-1, was seen in 35 patients (50%), and due to liposomal amphotericin B 3 mg kg-1 in 34 patients (54%). This was a statistically significant difference (P = 0.001). It was concluded that liposomal amphotericin B was safer than conventional amphotericin B, but both formulations are equivalent in treatment efficacy. The prophylactic use of amphotericin B in these immunocompromised patients is discussed.

Safety, tolerance, and pharmacokinetics of a small unilamellar liposomal formulation of amphotericin B (AmBisome) in neutropenic patients

The safety, tolerance, and pharmacokinetics of a small unilamellar liposomal formulation of amphotericin B (AmBisome) administered for empirical antifungal therapy were evaluated for 36 persistently febrile neutropenic adults receiving cancer chemotherapy and bone marrow transplantation. The protocol was an open-label, sequential-dose-escalation, multidose pharmacokinetic study which enrolled a total of 8 to 12 patients in each of the four dosage cohorts. Each cohort received daily doses of either 1.0, 2.5, 5.0, or 7.5 mg of amphotericin B in the form of AmBisome/kg of body weight. The study population consisted of patients between the ages of 13 and 80 years with neutropenia (absolute neutrophil count, <500/mm3) who were eligible to receive empirical antifungal therapy. Patients were monitored for safety and tolerance by frequent laboratory examinations and the monitoring of infusion-related reactions. Efficacy was assessed by monitoring for the development of invasive fungal infection. The pharmacokinetic parameters of AmBisome were measured as those of amphotericin B by high-performance liquid chromatography. Noncompartmental methods were used to calculate pharmacokinetic parameters. AmBisome administered as a 1-h infusion in this population was well tolerated and was seldom associated with infusion-related toxicity. Infusion-related side effects occurred in 15 (5%) of all 331 infusions, and only two patients (5%) required premedication. Serum creatinine, potassium, and magnesium levels were not significantly changed from baseline in any of the dosage cohorts, and there was no net increase in serum transaminase levels. AmBisome followed a nonlinear dosage relationship that was consistent with reticuloendothelial uptake and redistribution. There were no breakthrough fungal infections during empirical therapy with AmBisome. AmBisome administered to febrile neutropenic patients in this study was well tolerated, was seldom associated with infusion-related toxicity, was characterized by nonlinear saturation kinetics, and was effective in preventing breakthrough fungal infections.

Pharmacokinetics of liposomal amphotericin B (Ambisome) in critically ill patients

The liposomal formulation of amphotericin B (AmBisome) greatly reduces the acute and chronic side effects of the parent drug. The present study describes the pharmacokinetic characteristics of AmBisome applied to 10 patients at a dose of 2.8 to 3.0 mg/kg of body weight and compares them to the pharmacokinetics observed in 6 patients treated with amphotericin B deoxycholate at the standard dose of 1.0 mg/kg. Interpatient variabilities of amphotericin B peak concentrations (Cmax) and areas under concentration-time curves (AUC) were 8- to 10-fold greater for patients treated with AmBisome than for patients treated with amphotericin B deoxycholate. At the threefold greater dose of AmBisome, median Cmaxs were 8.4-fold higher (14.4 versus 1.7 microg/ml) and median AUCs exceeded those observed with amphotericin B deoxycholate by 9-fold. This was in part explained by a 5.7-fold lower volume of distribution (0.42 liters/kg) in AmBisome-treated patients. The elimination of amphotericin B from serum was biphasic for both formulations. However, the apparent half-life of elimination was twofold shorter for AmBisome (P = 0.03). Neither hemodialysis nor hemofiltration had a significant impact on AmBisome pharmacokinetics as analyzed in one patient. In conclusion, the liposomal formulation of amphotericin B significantly (P = 0.001) reduces the volume of drug distribution, thereby allowing for greater drug concentrations in serum. The low toxicity of AmBisome therefore cannot readily be explained by its serum pharmacokinetics.

Treatment of deep mycoses with liposomal amphotericin B

Amphotericin B is the mainstay of therapy of many deep mycoses, but its use is seriously hampered by dose-limiting nephrotoxicity. In this study a liposomal formulation of amphotericin B was administered to ten patients with proven deep mycoses: invasive aspergillosis (n = 4), deep candidiasis (n = 4) and zygomycosis (n = 2). The mean daily dosage of liposomal amphotericin B was 3.0 mg/kg (range 2.5 to 4 mg/kg), the mean total dosage of liposomal amphotericin B 2,781 mg (range 87 to 5,220 mg) and the mean duration of treatment 17 days (range 3 to 33 days). Treatment with liposomal amphotericin B was associated with little nephrotoxicity and an overall survival rate of 50%. The median increase of serum creatinine from baseline levels was 0.38 mg/dl (-1.2 to 2.6 mg/dl).

Liposomal amphotericin B (AmBisome) treatment of invasive fungal infections in immunocompromised children

Thirteen children were treated for 16 cases of proven (8 cases) or suspected (8 cases) invasive fungal infections caused by Candida spp. (9 cases), Aspergillus spp. (3 cases) and mycetoma (1 case). The type of fungal infection was not identified in 3 cases. Liposomal amphotericin B (AmBisome) was instituted because of the failure of previous treatments in 9 cases, toxicity-associated amphotericin B therapy in 4 cases and renal insufficiency in 3 cases. AmBisome was given for a median of 19 days (range 3-55) with a mean cumulative dose of 1.8 +/- 1.3 g (+/- SD). Acute toxic side-effects were not seen in any patients. Slight increases in serum creatinine were seen in 3 cases during AmBisome therapy. No other side-effects were observed. Among 8 cases with proven invasive fungal infection, 6 were clinically cured, one had persistent fungi and one died after only 3 days of AmBisome therapy. Eradication of fungi was documented in 5 out of 6 cases. Among the 8 cases with presumed fungal infections, 6 were clinically cured, one improved and one died after 6 days of treatment. To conclude, AmBisome can safely be given to children with invasive fungal infections; side-effects are minimal and among those treated for at least a week, the overall cure rate was 86% (12 out of 14).

A retrospective clinical comparison between antifungal treatment with liposomal amphotericin B (AmBisome) and conventional amphotericin B in transplant recipients

Invasive fungal infections are an important cause of morbidity and mortality in immunosuppressed bone marrow and solid organ transplant recipients. Treatment with amphotericin B, the drug of choice for these infections, is however often limited by toxicity. Ten transplant patients receiving a liposomal amphotericin B formulation (AmBisome) were compared to ten retrospective control patients given conventional amphotericin B. Each group included bone marrow (8), kidney (1), and liver transplant (1) recipients. Conventional amphotericin B treatment was instituted due to nine Candida infections, and one Aspergillus fumigatus infection. In the AmBisome group treatment was instituted due to eight Candida infections, one infection caused by Saccharomyces cerevisiae and in one case as prophylactic treatment. In the amphotericin B group, maximal daily doses ranged from 0.1 to 0.65 mg kg-1 and cumulative doses were 21-836 mg kg-1 and were given over 3-32 days. In the AmBisome group, maximal daily doses ranged from 0.9 to 2.3 mg kg-1 and cumulative doses ranged from 225 to 3525 mg kg-1 over 8-28 days. All patients in the amphotericin B group experienced severe toxicity, especially nephrotoxicity which in four cases caused withdrawal of the drug. In contrast, the only adverse reaction in the AmBisome group was cholestasis in one patient. Only three out of ten patients in the amphotericin B group responded to treatment, seven patients died and six patients still had evidence of invasive fungal infection at autopsy. In contrast, eight out of nine patients in the AmBisome group responded to treatment, and the patient that received prophylaxis had a successful course.