Population pharmacokinetics of liposomal amphotericin B in adults with HIV-associated cryptococcal meningoencephalitis.

BACKGROUND: Single, high-dose liposomal amphotericin B (LAmB; AmBisome, Gilead Sciences) has demonstrated non-inferiority to amphotericin B deoxycholate in combination with other antifungals for averting all-cause mortality from HIV-associated cryptococcal meningitis. There are limited data on the pharmacokinetics (PK) of AmBisome. The aim of this study was to describe population PK of AmBisome and conduct a meta-analysis of the available studies to suggest the optimal dosing for cryptococcal meningoencephalitis. METHODS: Data from a Phase II and Phase III trial of high-dose, short-course AmBisome for cryptococcal meningoencephalitis were combined to develop a population PK model. A search was conducted for trials of AmBisome monotherapy and meta-analysis of clinical outcome data was performed. RESULTS: A two-compartment model with first-order clearance of drug from the central compartment fitted the data best and enabled the extent of inter-individual variability in PK to be quantified. Mean (SD) population PK parameter estimates were: clearance 0.416 (0.363)  L/h; volume of distribution 4.566 (4.518) L; first-order transfer of drug from central to peripheral compartments 2.222 (3.351)  h-1, and from peripheral to central compartment 2.951 (4.070)  h-1. Data for the meta-analysis were insufficient to suggest optimal dosing of AmBisome for cryptococcal meningoencephalitis. CONCLUSIONS: This study provides novel insight into the PK of AmBisome at the population level and the variability therein. Our analysis also serves to highlight the paucity of data available on the pharmacodynamics (PD) of AmBisome and underscores the importance of thorough and detailed PK/PD analysis in the development of novel antifungals, by demonstrating the challenges associated with post hoc PK/PD analysis.

Short-course High-dose Liposomal Amphotericin B for Human Immunodeficiency Virus-associated Cryptococcal Meningitis: A Phase 2 Randomized Controlled Trial.

Background: We performed a phase 2 noninferiority trial examining the early fungicidal activity (EFA) of 3 short-course, high-dose liposomal amphotericin B (L-AmB) regimens for cryptococcal meningitis (CM) in Tanzania and Botswana. Methods: Human immunodeficiency virus (HIV)-infected adults with CM were randomized to (i) L-AmB 10 mg/kg on day 1 (single dose); (ii) L-AmB 10 mg/kg on day 1 and 5 mg/kg on day 3 (2 doses); (iii) L-AmB 10 mg/kg on day 1 and 5 mg/kg on days 3 and 7 (3 doses); or (iv) L-AmB 3 mg/kg/day for 14 days (control). All patients also received oral fluconazole 1200 mg/day for 14 days. Primary endpoint was mean rate of clearance of cerebrospinal fluid cryptococcal infection (EFA). Noninferiority was defined as an upper limit of the 2-sided 95% confidence interval (CI) of difference in EFA between intervention and control <0.2 log10 colony-forming units (CFU)/mL/day. Results: Eighty participants were enrolled. EFA for daily L-AmB was -0.41 log10 CFU/mL/day (standard deviation, 0.11; n = 17). Difference in mean EFA from control was -0.11 (95% CI, -.29 to .07) log10 CFU/mL/day faster with single dose (n = 16); -0.05 (95% CI, -.20 to .10) log10 CFU/mL/day faster with 2 doses (n = 18); and -0.13 (95% CI, -.35 to .09) log10 CFU/mL/day faster with 3 doses (n = 18). EFA in all short-course arms was noninferior to control. Ten-week mortality was 29% (n = 23) with no statistical difference between arms. All arms were well tolerated. Conclusions: Single-dose 10 mg/kg L-AmB was well tolerated and led to noninferior EFA compared to 14 days of 3 mg/kg/day L-AmB in HIV-associated CM. Induction based on a single 10 mg/kg L-AmB dose is being taken forward to a phase 3 clinical endpoint trial. Clinical Trials Registration: ISRCTN 10248064.

AMBITION-cm: intermittent high dose AmBisome on a high dose fluconazole backbone for cryptococcal meningitis induction therapy in sub-Saharan Africa: study protocol for a randomized controlled trial.

BACKGROUND: Cryptococcal meningitis (CM) is a leading cause of mortality among HIV-infected individuals in Africa. Poor outcomes from conventional antifungal therapies, unavailability of flucytosine, and difficulties administering 14 days of amphotericin B are key drivers of this mortality. Novel treatment regimes are needed. This study examines whether short-course high-dose liposomal amphotericin B (AmBisome), given with high dose fluconazole, is non-inferior (in terms of microbiological and clinical endpoints) to standard-dose 14-day courses of AmBisome plus high dose fluconazole for treatment of HIV-associated CM. METHODOLOGY/DESIGN: This is an adaptive open-label phase II/III randomised non-inferiority trial comparing alternative short course AmBisome regimens. Step 1 (phase II) will compare four treatment arms in 160 adult patients (≥ 18 years old) with a first episode of HIV-associated CM, using early fungicidal activity (EFA) as the primary outcome: 1) AmBisome 10 mg/kg day one (single dose); 2) AmBisome 10 mg/kg day one and AmBisome 5 mg/kg day three (two doses); 3) AmBisome 10 mg/kg day one, and AmBisome 5 mg/kg days three and seven (three doses); and 4) AmBisome 3 mg/kg/d for 14 days (control); all given with fluconazole 1200 mg daily for 14 days. STEP 2 (phase III) will enrol 300 participants and compare two treatment arms using all-cause mortality within 70 days as the primary outcome: 1) the shortest course AmBisome regimen found to be non-inferior in terms of EFA to the 14-day control arm in STEP 1, and 2) AmBisome 3 mg/kg/d for 14 days (control), both given with fluconazole 1200 mg daily for 14 days. STEP 2 analysis will include all patients from STEP 1 and STEP 2 taking the STEP 2 regimens. All patients will be followed for ten weeks, and mortality and safety data recorded. All patients will receive consolidation therapy with fluconazole 400-800 mg daily and ART in accordance with local guidelines. The primary analysis (for both STEP 1 and STEP 2) will be intention-to-treat. TRIAL REGISTRATION: ISRCTN10248064. Date of Registration: 22 January 2014.

Utility of urine and serum lateral flow assays to determine the prevalence and predictors of cryptococcal antigenemia in HIV-positive outpatients beginning antiretroviral therapy in Mwanza, Tanzania.

BACKGROUND: Detection of subclinical cryptococcal disease using cryptococcal antigen screening among HIV-positive individuals presents a potential opportunity for prevention of both clinical disease and death if patients with detectable cryptococcal antigen are identified and treated pre-emptively. Recently developed point-of-care cryptococcal antigen tests may be useful for screening, particularly in resource-limiting settings, but few studies have assessed their utility. METHODOLOGY: The objectives of this study were to determine the prevalence and factors associated with cryptococcal antigenemia in HIV-positive patients with CD4(+) T-cell counts ≤200 cells/µL who were initiating ART, and also to evaluate the utility of the point-of-care urine lateral flow assay (LFA) cryptococcal antigen test using two different diluents, compared to gold standard serum antigen testing, as a screening tool. Urine and serum of outpatients initiating antiretroviral therapy at two hospitals in Mwanza were tested for cryptococcal antigen, and demographic and clinical characteristics were obtained using structured questionnaires and patients' files. Patients with asymptomatic cryptococcal antigenemia received oral fluconazole in accordance with World Health Organization recommendations. RESULTS: Among 140 patients screened, 10 (7.1%) had asymptomatic cryptococcal antigenemia with a positive serum cryptococcal antigen. Four of these ten patients had CD4 counts between 100 and 200 cells/µL. The prevalence of cryptococcal antigen detected in urine using a standard (older) and a test (newer) diluent were 44 (31.4%) and 19 (13.6%), with Kappa coefficients compared to serum of 0.28 and 0.51 (p<0.001 for both). Compared to the new LFA diluent for urine cryptococcal antigen, the standard diluent had higher sensitivity (100% versus 80%) but lower specificity (74% versus 92%) using serum cryptococcal antigen as a gold standard. CONCLUSIONS: Our findings suggest that HIV-positive outpatients with CD4 counts <200 cells/µL, rather than 100, should be screened for asymptomatic cryptococcal antigenemia given its association with mortality if untreated. Agreement of the urine LFA with the serum LFA was not sufficient to recommend routine screening with urine LFA.

Oesophageal varices, schistosomiasis, and mortality among patients admitted with haematemesis in Mwanza, Tanzania: a prospective cohort study.

BACKGROUND: Upper gastrointestinal bleeding (UGIB) is a common cause of hospital admissions worldwide. Aetiologies vary by sociodemographics and geography. Retrospective studies of endoscopies in much of Africa have documented oesophageal varices as a leading cause of UGIB. Prospective studies describing outcomes and associations with clinical factors are lacking. METHODS: We conducted a prospective cohort study at a referral hospital in Mwanza, Tanzania where schistosomiasis is endemic. Adults admitted with haematemesis underwent laboratory workup, schistosomiasis antigen testing and elective endoscopy, and were followed for two months for death or re-bleeding. We assessed predictors of endoscopic findings using logistic regression models, and determined prediction rules that maximised sensitivity and positive predictive value (PPV). RESULTS: Of 124 enrolled patients, 13 died within two months (10%); active schistosomiasis prevalence was 48%. 64/91(70%) patients had oesophageal varices. We found strong associations between varices and numerous demographic or clinical findings, permitting construction of simple, high-fidelity prediction rules for oesophageal varices applicable even in rural settings. Portal vein diameter ≥ 13 mm or water sourced from the lake yielded sensitivity, specificity, PPV and NPV >90% for oesophageal varices; presence of splenomegaly or water sourced from the lake maintained sensitivity and PPV >90%. CONCLUSIONS: Our results guide identification of patients, via ultrasound and clinical examination, likely to have varices for whom referral for endoscopy may be life-saving. Furthermore, they support empiric anti-schistosome treatment for patients with UGIB in schistosome-endemic regions. These interventions have potential to reduce UGIB-related morbidity and mortality in Africa.

Cryptococcal meningitis management in Tanzania with strict schedule of serial lumber punctures using intravenous tubing sets: an operational research study.

BACKGROUND: Cryptococcal meningitis (CM) has a mortality rate of ∼70% among HIV-infected adults in low-income countries. Controlling intracranial pressure (ICP) is essential in CM, but it is difficult in low-income countries because manometers and practical ICP management protocols are lacking. METHODS: As part of a continuous quality improvement project, our Tanzanian hospital initiated a new protocol for ICP management for CM. All adult inpatients with CM are included in a prospective patient registry. At the time of analysis, this registry included data from 2 years before the initiation of this new ICP management protocol and for a 9-month period after. ICP was measured at baseline and at days 3, 7, and 14 by both manometer and intravenous (IV) tubing set. All patients were given IV fluconazole according to Tanzanian treatment guidelines and were followed until 30 days after admission. RESULTS: Among adult inpatients with CM, 32 of 35 patients (91%) had elevated ICP on admission. Cerebrospinal fluid pressure measurements using the improvised IV tubing set demonstrated excellent agreement (r = 0.96) with manometer measurements. Compared with historical controls, the new ICP management protocol was associated with a significant reduction in 30-day mortality (16/35 [46%] vs. 48/64 [75%] in historical controls; hazard ratio = 2.1 [95% CI: 1.1 to 3.8]; P = 0.018]. CONCLUSIONS: Increased ICP is almost universal among HIV-infected adults admitted with CM in Tanzania. Intensive ICP management with a strict schedule of serial lumbar punctures reduced in-hospital mortality compared with historical controls. ICP measurement with IV tubing sets may be a good alternative in resource-limited health facilities where manometers are not available.