The Next Generation Scientist program: capacity-building for future scientific leaders in low- and middle-income countries.

BACKGROUND: Scientific and professional development opportunities for early career scientists in low- and middle- income countries (LMICs) are limited and not consistent. There is a disproportionately low number of biomedical and clinical researchers in LMIC's relative to their high burden of disease, a disparity that is aggravated by emigration of up to 70% of scientists from their countries of birth for education and employment elsewhere. To help address this need, a novel University-accredited, immersive fellowship program was established by a large public-academic-private network. We sought to describe the program and summarize progress and lessons learned over its first 7-years. METHODS: Hallmarks of the program are a structured learning curriculum and bespoke research activities tailored to the needs of each fellow. Research projects expose the scientists to state-of-the-art methodologies and leading experts in their fields while also ensuring that learnings are implementable within their home infrastructure. Fellows run seminars on drug discovery and development that reinforce themes of scientific leadership and teamwork together with practical modules on addressing healthcare challenges within their local systems. Industry mentors achieve mutual learning to better understand healthcare needs in traditionally underserved settings. We evaluated the impact of the program through an online survey of participants and by assessing research output. RESULTS: More than 140 scientists and clinicians from 25 countries participated over the 7-year period. Evaluation revealed strong evidence of knowledge and skills transfer, and beneficial self-reported impact on fellow's research output and career trajectories. Examples of program impact included completion of post-graduate qualifications; establishment and implementation of good laboratory- and clinical- practice mechanisms; and becoming lead investigators in local programs. There was a high retention of fellows in their home countries (> 75%) and an enduring professional network among the fellows and their mentors. CONCLUSIONS: Our experience demonstrates an example for how multi-sectoral partners can contribute to scientific and professional development of researchers in LMICs and supports the idea that capacity-building efforts should be tailored to the specific needs of beneficiaries to be maximally effective. Lessons learned may be applied to the design and conduct of other programs to strengthen science ecosystems in LMICs.

Prevalence of rheumatic heart disease in Zambian school children.

BACKGROUND: The large global burden of rheumatic heart disease (RHD) has come to light in recent years following robust epidemiologic studies. As an operational research component of a broad program aimed at primary and secondary prevention of RHD, we sought to determine the current prevalence of RHD in the country's capital, Lusaka, using a modern imaging-based screening methodology. In addition, we wished to evaluate the practicality of training local radiographers in echocardiography screening methods. METHODS: Echocardiography was conducted on a random sample of students in 15 schools utilizing a previously validated, abbreviated screening protocol. Through a task-shifting scheme, and in the spirit of capacity-building to enhance local diagnostic and research skills, general radiographers based at Lusaka University Teaching Hospital (UTH) were newly trained to use portable echocardiography devices. Students deemed as screen-positive were referred for comprehensive echocardiography and clinical examination at UTH. Cardiac abnormalities were classified according to standard World Heart Federation criteria. RESULTS: Of 1102 students that were consented and screened, 53 students were referred for confirmatory echocardiography. Three students had definite RHD, 10 had borderline RHD, 29 were normal, and 11 students were lost to follow-up. The rates of definite, borderline, and total RHD were 2.7 per 1000, 9.1 per 1000, and 11.8 per 1000, respectively. Anterior mitral valve leaflet thickening and chordal thickening were the most common morphological defects. The pairwise kappa test showed fair agreement between the local radiographers and an echocardiographer quality assurance specialist. CONCLUSION: The prevalence of asymptomatic RHD in urban communities in Zambia is within the range of results reported in other sub-Saharan African countries using the WHF criteria. Task-shifting local radiographers to conduct echocardiography was feasible. The results of this study will be used to inform ongoing efforts in Zambia to control and eventually eliminate RHD. TRIAL REGISTRATION: The study was registered on clinicaltrials.gov ( #NCT02661763 ).

Tolerability and pharmacokinetics of ACT-280778, a novel nondihydropyridine dual L/T-type calcium channel blocker: early clinical studies in healthy male subjects using adaptive designs.

ACT-280778 is a novel nondihydropyridine dual L/T-type calcium channel blocker. Two clinical studies (AC-067-101 and AC-067-102) were conducted to characterize its safety, tolerability, and pharmacokinetics in healthy male subjects after oral administration of single and multiple doses. Both trials were single-center, randomized, double-blind, placebo-controlled, adaptive design, ascending-dose studies, in which ACT-280778 was administrated as single doses of 2, 5, 15, or 40 mg, or as once-daily doses of 5 or 15 mg for 7 days. Single and multiple doses up to and including 15 mg were well tolerated, and no serious or severe adverse event was reported in either study. A single dose of 40 mg was associated with abnormal electrocardiogram findings resulting in the discontinuation of further treatment at this dose or higher doses. ACT-280778 was rapidly absorbed, and larger than dose-proportional increases of the maximum plasma concentration and area under the plasma concentration-time curve were observed. Food intake delayed the time to maximum plasma concentration and doubled exposure. Urinary excretion of unchanged ACT-280778 was negligible, and accumulation at steady state was modest. Overall, pharmacokinetic and tolerability profiles of ACT-280778 observed in these 2 studies warranted further evaluation of ACT-280778 in a proof-of-concept study in patients with hypertension.

Relative bioavailability of a newly developed pediatric formulation of bosentan vs. the adult formulation.

WHAT IS KNOWN: Bosentan is a dual endothelin receptor antagonist approved for the treatment of pulmonary arterial hypertension (PAH). Since bosentan is frequently used to treat pediatric PAH patients, a pediatric formulation was developed. AIM: To evaluate the pharmacokinetic properties of bosentan and its active metabolite, Ro 48-5033, of the quadrisected, dispersible pediatric vs. the adult tablet after single-dose administration to healthy subjects. Secondary objectives of the study were to compare the pharmacokinetics of two inactive metabolites and the safety of both formulations. MATERIALS AND METHODS: In this open-label, two-way crossover study, subjects (20 - 43 years) were randomized to receive single oral doses of 62.5 mg of bosentan as 1 adult tablet and 64 mg as 2 pediatric tablets of 32 mg. Blood samples were drawn over a 48-hour period to measure bosentan and its metabolites. RESULTS: 16 subjects were enrolled and completed the study. Following treatment with the pediatric formulation, values for Cmax and AUC0-∞ of bosentan were lower than with the adult formulation with geometric mean ratios (90% confidence interval) of 0.82 (0.65, 1.04) and 0.87 (0.78, 0.97), respectively. Similar results were obtained for the primary active metabolite Ro 48-5033. Both treatments were well tolerated. WHAT IS NEW AND CONCLUSION: Although the 90% confidence intervals of the geometric mean ratios of Cmax and AUC0-∞ were not entirely within the conventional bioequivalence range (0.80 - 1.25), no clinically relevant effect of formulation on the pharmacokinetics of bosentan and Ro 48-5033 was detected. Both formulations were well tolerated.

Comparative pharmacokinetic, pharmacodynamic, safety, and tolerability profiles of 3 different formulations of epoprostenol sodium for injection in healthy men.

BACKGROUND: Epoprostenol sodium for injection is approved for the treatment of severe cases of primary pulmonary arterial hypertension. Currently, there are 3 approved formulations of this drug containing the same active ingredient (epoprostenol sodium) but differing with regard to excipients. When compared with epoprostenol sodium formulated with glycine-mannitol (epoprostenol GM), 2 new formulations of epoprostenol sodium, one formulated with arginine-mannitol (epoprostenol AM) and one formulated with arginine-sucrose (epoprostenol AS), have improved stability after reconstitution and dilution. The biocomparability of epoprostenol AM and epoprostenol GM, with regard to pharmacokinetic (PK), pharmacodynamic (PD), safety, and tolerability profiles, has been shown previously. OBJECTIVE: This study compared PK, PD, safety, and tolerability profiles of the 3 different formulations of epoprostenol sodium for injection. METHODS: This was a prospective, single-center, open-label, 2-period, 2-treatment, randomized, crossover, ascending dose study in 2 parts. Twenty healthy men in part 1 and 20 different individuals in part 2 received epoprostenol AM and epoprostenol AS and epoprostenol GM and epoprostenol AS, respectively, in a crossover fashion, as sequential IV infusions of 2, 4, 6, and 8 ng/kg/min for 2 hours each. In each part, the PK profile of epoprostenol was characterized via analysis of the concentration-time profiles of its 2 primary metabolites: 6-keto-prostacyclin F1α and 6,15-diketo-13,14-dihydro-prostacyclin F1α. The effect of the formulations was assessed using the 90% CI of the geometric mean ratio calculated for the exposure PK parameters. The PD variables cardiac output, cardiac index, and heart rate were assessed using echocardiography. Adverse events were recorded through the study. RESULTS: The plasma concentration versus time curves of epoprostenol AM and epoprostenol AS in part 1 and epoprostenol GM and epoprostenol AS in part 2 were similar in shape and almost superimposable. For each study part, the 90% CIs of ratios of geometric means for AUC0-∞ of the assessed epoprostenol formulations were within the range for bioequivalence (0.8-1.25). The increases in cardiac output, cardiac index, and heart rate resulting from infusion with epoprostenol sodium were comparable between all formulations, with maximum values attained after 8 hours. Almost all study participants reported at least one treatment-emergent adverse event, the most common being headache, which was reported in 80% to 85% of study participants. CONCLUSIONS: Overall, the PK, PD, safety, and tolerability profiles of the 3 formulations of epoprostenol sodium for injection are comparable and meet the criteria of bioequivalence. Australian New Zealand Clinical Trials Registry identifier: ACTRN12612001086853.

Integrated pharmacokinetics and pharmacodynamics of epoprostenol in healthy subjects.

AIM: The aim of the study was to report the first thorough characterization of the pharmacokinetics (PK) and pharmacodynamics (PD) of epoprostenol in an integrated manner. METHOD: Twenty healthy male subjects received two formulations of i.v. epoprostenol, in a crossover design, in sequential infusions of 2, 4, 6 and 8 ng kg(-1) min(-1) for 2 h each. A sensitive assay was developed which allowed accurate PK characterization of epoprostenol via analysis of the concentration-time profiles of its two primary metabolites, 6-keto-prostacyclin F(1α) and 6,15-diketo-13,14-dihydro-prostacyclin F(1α) . PD parameters included cardiac output (CO), cardiac index (CIn) and heart rate (HR). RESULTS: The pharmacokinetics of epoprostenol deviated slightly from dose-proportionality, probably due to a food effect. After infusion of the two formulations of epoprostenol, the t(1/2) values expressed as geometric mean (95% confidence interval) were 0.25 h (0.14, 0.46) and 0.22 h (0.13, 0.38) for 6-keto-prostacyclin F(1α) , and 0.32 h (0.22, 0.45) and 0.34 h (0.26, 0.46) for 6,15-diketo-13,14-dihydro-prostacyclin F(1α) . A single compartment infusion model with first order elimination adequately described the PK of 6-keto-prostacyclin F(1α) . This model also characterized the food effect. Stepwise infusions with epoprostenol resulted in a progressive increase in CO, CIn and HR. CONCLUSION: Of the two metabolites analyzed, the appearance of 6-keto-prostacyclin F(1α) in plasma was more closely associated with the haemodynamic effects of i.v. epoprostenol. PK and PD profiles showed that CIn relates proportionally and linearly to the plasma concentrations of 6-keto-prostacyclin F(1α) . These results suggest that 6-keto-prostacyclin F(1α) is a suitable surrogate marker of plasma concentrations of epoprostenol.

Entry-into-humans study with a new direct renin inhibitor.

PURPOSE: To evaluate the pharmacokinetics, pharmacodynamics, safety, and tolerability of escalating single oral doses of ACT-077825, a novel orally active renin inhibitor, in healthy male subjects. METHODS: In this single-center, double-blind, placebo- and active-controlled (with enalapril) randomized study, 70 subjects received a single dose of ACT-077825 (1-1,000 mg), placebo, or enalapril 20 mg under fasted conditions. The main pharmacokinetic endpoints were area under the plasma ACT-077825 concentration-time curve from time zero to infinity and the terminal half-life (t(1/2)). The pharmacodynamic endpoints included immunoactive active renin (iAR) plasma concentrations and plasma renin activity (PRA). Standard laboratory and safety data were collected. RESULTS: Of the few adverse events reported, diarrhea and headache were the most frequent. The pharmacokinetics of ACT-077825 were dose-proportional in the dose range 100 to 1,000 mg. Terminal t(1/2), best characterized following a dose of 1,000 mg, was 41.6 h and t(max) 4-5 h post-dose. ACT-077825 dose-dependently increased iAR and decreased PRA, effects that were associated with a decrease in blood pressure at 1,000 mg, similar to following treatment with enalapril. CONCLUSION: The results provide evidence that ACT-077825, with a pharmacokinetic profile consistent with a once-a-day dosing regimen, may represent an effective antihypertensive agent and pave the way toward a multiple-ascending dose study.

A randomized, placebo-controlled trial of citalopram for the treatment of major depression in children and adolescents.

OBJECTIVE: Open-label trials with the selective serotonin reuptake inhibitor citalopram suggest that this agent is effective and safe for the treatment of depressive symptoms in children and adolescents. The current study investigated the efficacy and safety of citalopram compared with placebo in the treatment of pediatric patients with major depression. METHOD: An 8-week, randomized, double-blind, placebo-controlled study compared the safety and efficacy of citalopram with placebo in the treatment of children (ages 7-11) and adolescents (ages 12-17) with major depressive disorder. Diagnosis was established with the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version. Patients (N=174) were treated initially with placebo or 20 mg/day of citalopram, with an option to increase the dose to 40 mg/day at week 4 if clinically indicated. The primary outcome measure was score on the Children's Depression Rating Scale-Revised; the response criterion was defined as a score of < or =28. RESULTS: The overall mean citalopram dose was approximately 24 mg/day. Mean Children's Depression Rating Scale-Revised scores decreased significantly more from baseline in the citalopram treatment group than in the placebo treatment group, beginning at week 1 and continuing at every observation point to the end of the study (effect size=2.9). The difference in response rate at week 8 between placebo (24%) and citalopram (36%) also was statistically significant. Citalopram treatment was well tolerated. Rates of discontinuation due to adverse events were comparable in the placebo and citalopram groups (5.9% versus 5.6%, respectively). Rhinitis, nausea, and abdominal pain were the only adverse events to occur with a frequency exceeding 10% in either treatment group. CONCLUSIONS: In this population of children and adolescents, treatment with citalopram reduced depressive symptoms to a significantly greater extent than placebo treatment and was well tolerated.

An evaluation of the potential for pharmacokinetic interaction between escitalopram and the cytochrome P450 3A4 inhibitor ritonavir.

BACKGROUND: Depression often coexists with a number of disease states, and patients with a diagnosis of depression often receive multiple medications. Thus, it is desirable to avoid coadministration of agents that have a potential for drug interactions in these patients. Although escitalopram and its metabolites are weak to negligible inhibitors of the cytochrome P450 (CYP) 3A4 isozyme and are therefore unlikely to affect plasma concentrations of ritonavir (a CYP3A4 substrate and prototype CYP3A4 inhibitor), ritonavir may potentially affect plasma concentrations of escitalopram, as CYP3A4 is partially responsible for conversion of escitalopram to its major metabolite, S-demethylcitalopram (S-DCT). OBJECTIVES: The aim of this study was to investigate the potential for pharmacokinetic interaction between escitalopram and ritonavir after concomitant administration of a single dose of each in healthy young subjects. METHODS: In this single-center, randomized, open-label, 3-way crossover study, subjects received each of the following: a single dose of escitalopram 20 mg, a single dose of ritonavir 600 mg, and single doses of both escitalopram 20 mg and ritonavir 600 mg. Blood was collected and plasma was analyzed for the pharmacokinetic parameters (maximum plasma concentration [C(max)], time to C(max) [T(max)], area under the plasma concentration-time curve, plasma elimination half-life, oral clearance, and apparent volume of distribution) of escitalopram, S-DCT, and ritonavir. RESULTS: Of 21 subjects (11 men, 10 women; mean [SD] age, 28.4 [4.4] years) who were enrolled, 18 completed the study. After concomitant administration of escitalopram and ritonavir, no statistically significant differences were noted in the pharmacokinetics of escitalopram, with the exception of apparent volume of distribution, which was reduced by approximately 10% (P < 0.001). The pharmacokinetics of S-DCT were unaffected by coadministration of ritonavir, with the exception of T(max), which was increased in the presence of ritonavir. The pharmacokinetic parameters of ritonavir were also unaffected by coadministration of escitalopram. CONCLUSION: In general, no pharmacokinetic interaction was observed between escitalopram and ritonavir in the present study.