Comparison of Dual Therapies for Lowering Blood Pressure in Black Africans.

BACKGROUND: The prevalence of hypertension among black African patients is high, and these patients usually need two or more medications for blood-pressure control. However, the most effective two-drug combination that is currently available for blood-pressure control in these patients has not been established. METHODS: In this randomized, single-blind, three-group trial conducted in six countries in sub-Saharan Africa, we randomly assigned 728 black patients with uncontrolled hypertension (≥140/90 mm Hg while the patient was not being treated or was taking only one antihypertensive drug) to receive a daily regimen of 5 mg of amlodipine plus 12.5 mg of hydrochlorothiazide, 5 mg of amlodipine plus 4 mg of perindopril, or 4 mg of perindopril plus 12.5 mg of hydrochlorothiazide for 2 months. Doses were then doubled (10 and 25 mg, 10 and 8 mg, and 8 and 25 mg, respectively) for an additional 4 months. The primary end point was the change in the 24-hour ambulatory systolic blood pressure between baseline and 6 months. RESULTS: The mean age of the patients was 51 years, and 63% were women. Among the 621 patients who underwent 24-hour blood-pressure monitoring at baseline and at 6 months, those receiving amlodipine plus hydrochlorothiazide and those receiving amlodipine plus perindopril had a lower 24-hour ambulatory systolic blood pressure than those receiving perindopril plus hydrochlorothiazide (between-group difference in the change from baseline, -3.14 mm Hg; 95% confidence interval [CI], -5.90 to -0.38; P = 0.03; and -3.00 mm Hg; 95% CI, -5.8 to -0.20; P = 0.04, respectively). The difference between the group receiving amlodipine plus hydrochlorothiazide and the group receiving amlodipine plus perindopril was -0.14 mm Hg (95% CI, -2.90 to 2.61; P=0.92). Similar differential effects on office and ambulatory diastolic blood pressures, along with blood-pressure control and response rates, were apparent among the three groups. CONCLUSIONS: These findings suggest that in black patients in sub-Saharan Africa, amlodipine plus either hydrochlorothiazide or perindopril was more effective than perindopril plus hydrochlorothiazide at lowering blood pressure at 6 months. (Funded by GlaxoSmithKline Africa Noncommunicable Disease Open Lab; CREOLE ClinicalTrials.gov number, NCT02742467.).

Pharmacokinetic profile and safety of adjusted doses of darunavir/ritonavir with rifampicin in people living with HIV.

BACKGROUND: Darunavir/ritonavir is better tolerated than lopinavir/ritonavir and has a higher genetic barrier to resistance. Co-administration with rifampicin has been contraindicated as a significant reduction in darunavir exposure is expected. This is a barrier to darunavir/ritonavir use where TB is endemic. OBJECTIVES: To evaluate the safety and pharmacokinetic profile of adjusted doses of darunavir/ritonavir with rifampicin. METHODS: Virally suppressed participants on second-line lopinavir/ritonavir-based ART were switched to darunavir/ritonavir 800/100 mg q24h. In sequence: rifampicin was added; the dose of ritonavir was escalated; and darunavir was increased (darunavir/ritonavir 1600/200 mg q24h and 800/100 mg q12h were given in randomized sequence with rifampicin). Darunavir plasma concentrations were measured on the seventh/last day of each treatment period. To prevent viral rebound, dolutegravir (50 mg q12h) was added during rifampicin administration and for 1 week thereafter. Clinical events, ALT and bilirubin were monitored every 2-3 days during rifampicin administration. RESULTS: A total of 17/28 participants started study treatment. Six (35.3%) were withdrawn for symptomatic hepatitis with severe ALT elevations, developing after 9-11 days of rifampicin and 2-4 days of ritonavir 200 mg. The study was stopped prematurely due to this high rate of hepatotoxicity. Only four participants completed the study. All hepatotoxicity resolved on withdrawal of study treatment. All participants were successfully re-established on their lopinavir/ritonavir-based regimen. After doubling the darunavir/ritonavir doses on rifampicin, darunavir pre-dose concentrations approached those on standard doses without rifampicin for q12h doses, but not for q24h doses. CONCLUSIONS: Adjusted doses of darunavir/ritonavir with rifampicin had unacceptable risk of hepatotoxicity. Darunavir trough concentrations were markedly reduced with the daily adjusted dose.

Artificial intelligence-derived 3-Way Concentration-dependent Antagonism of Gatifloxacin, Pyrazinamide, and Rifampicin During Treatment of Pulmonary Tuberculosis.

Background: In the experimental arm of the OFLOTUB trial, gatifloxacin replaced ethambutol in the standard 4-month regimen for drug-susceptible pulmonary tuberculosis. The study included a nested pharmacokinetic (PK) study. We sought to determine if PK variability played a role in patient outcomes. Methods: Patients recruited in the trial were followed for 24 months, and relapse ascertained using spoligotyping. Blood was drawn for drug concentrations on 2 separate days during the first 2 months of therapy, and compartmental PK analyses was performed. Failure to attain sustained sputum culture conversion at the end of treatment, relapse, or death during follow-up defined therapy failure. In addition to standard statistical analyses, we utilized an ensemble of machine-learning methods to identify patterns and predictors of therapy failure from among 27 clinical and laboratory features. Results: Of 126 patients, 95 (75%) had favorable outcomes and 19 (15%) failed therapy, relapsed, or died. Pyrazinamide and rifampicin peak concentrations and area under the concentration-time curves (AUCs) were ranked higher (more important) than gatifloxacin AUCs. The distribution of individual drug concentrations and their ranking varied significantly between South African and West African trial sites; however, drug concentrations still accounted for 31% and 75% of variance of outcomes, respectively. We identified a 3-way antagonistic interaction of pyrazinamide, gatifloxacin, and rifampicin concentrations. These negative interactions disappeared if rifampicin peak concentration was above 7 mg/L. Conclusions: Concentration-dependent antagonism contributed to death, relapse, and therapy failure but was abrogated by high rifampicin concentrations. Therefore, increasing both rifampin and gatifloxacin doses could improve outcomes. Clinical Trials Registration: NCT00216385.

Gatifloxacin Pharmacokinetics/Pharmacodynamics-based Optimal Dosing for Pulmonary and Meningeal Multidrug-resistant Tuberculosis.

Background: Gatifloxacin is used for the treatment of multidrug-resistant tuberculosis (MDR-TB). The optimal dose is unknown. Methods: We performed a 28-day gatifloxacin hollow-fiber system model of tuberculosis (HFS-TB) study in order to identify the target exposures associated with optimal kill rates and resistance suppression. Monte Carlo experiments (MCE) were used to identify the dose that would achieve the target exposure in 10000 adult patients with meningeal or pulmonary MDR-TB. The optimal doses identified were validated using probit analyses of clinical data from 2 prospective clinical trials of patients with pulmonary and meningeal tuberculosis. Classification and regression-tree (CART) analyses were used to identify the gatifloxacin minimum inhibitory concentration (MIC) below which patients failed or relapsed on combination therapy. Results: The target exposure associated with optimal microbial kill rates and resistance suppression in the HFS-TB was a 0-24 hour area under the concentration-time curve-to-MIC of 184. MCE identified an optimal gatifloxacin dose of 800 mg/day for pulmonary and 1200 mg/day for meningeal MDR-TB, and a clinical susceptibility breakpoint of MIC ≤ 0.5 mg/L. In clinical trials, CART identified that 79% patients failed therapy if MIC was >2 mg/L, but 98% were cured if MIC was ≤0.5 mg/L. Probit analysis of clinical data demonstrated a >90% probability of a cure in patients if treated with 800 mg/day for pulmonary tuberculosis and 1200 mg/day for meningeal tuberculosis. Doses ≤400 mg/day were suboptimal. Conclusions: Gatifloxacin doses of 800 mg/day and 1200 mg/day are recommended for pulmonary and meningeal MDR-TB treatment, respectively. Gatifloxacin has a susceptible dose-dependent zone at MICs 0.5-2 mg/L.

Rationale and design of the comparison of 3 combination therapies in lowering blood pressure in black Africans (CREOLE study): 2 × 3 factorial randomized single-blind multicenter trial.

BACKGROUND: Current hypertension guidelines recommend the use of combination therapy as first-line treatment or early in the management of hypertensive patients. Although there are many possible combinations of blood pressure(BP)-lowering therapies, the best combination for the black population is still a subject of debate because no large randomized controlled trials have been conducted in this group to compare the efficacy of different combination therapies to address this issue. METHODS: The comparison of 3 combination therapies in lowering BP in the black Africans (CREOLE) study is a randomized single-blind trial that will compare the efficacy of amlodipine plus hydrochlorothiazide versus amlodipine plus perindopril and versus perindopril plus hydrochlorothiazide in blacks residing in sub-Saharan Africa (SSA). Seven hundred two patients aged 30-79 years with a sitting systolic BP of 140 mm Hg and above, and less than 160 mm Hg on antihypertensive monotherapy, or sitting systolic BP of 150 mm Hg and above, and less than 180 mm Hg on no treatment, will be centrally randomized into any of the 3 arms (234 into each arm). The CREOLE study is taking place in 10 sites in SSA, and the primary outcome measure is change in ambulatory systolic BP from baseline to 6 months. The first patient was randomized in June 2017, and the trial will be concluded by 2019. CONCLUSIONS: The CREOLE trial will provide unique information as to the most efficacious 2-drug combination in blacks residing in SSA and thereby inform the development of clinical guidelines for the treatment of hypertension in this subregion.

Evaluation of initial and steady-state gatifloxacin pharmacokinetics and dose in pulmonary tuberculosis patients by using monte carlo simulations.

A 4-month regimen of gatifloxacin with rifampin, isoniazid, and pyrazinamide is being evaluated for the treatment of tuberculosis in a phase 3 randomized controlled trial (OFLOTUB). A prior single-dose study found that gatifloxacin exposure increased by 14% in the combination. The aims of the study are to evaluate the initial and steady-state pharmacokinetics of gatifloxacin when daily doses are given to patients with newly diagnosed drug-sensitive pulmonary tuberculosis as part of a combination regimen and to evaluate the gatifloxacin dose with respect to the probability of attaining a pharmacokinetic/pharmacodynamic target. We describe the population pharmacokinetics of gatifloxacin from the first dose to a median of 28 days in 169 adults enrolled in the OFLOTUB trial in Benin, Guinea, Senegal, and South Africa. The probability of achieving a ratio of ≥125 for the area under the concentration time curve to infinity (AUC0-∞) for the free fraction of gatifloxacin over the MIC (fAUC/MIC) was investigated using Monte Carlo simulations. The median AUC0-∞ of 41.2 µg · h/ml decreased on average by 14.3% (90% confidence interval [CI], -90.5% to +61.5%) following multiple 400-mg daily doses. At steady state, 90% of patients achieved an fAUC/MIC of ≥125 only when the MIC was <0.125 µg/ml. We conclude that systemic exposure to gatifloxacin declines with repeated daily 400-mg doses when used together with rifampin, isoniazid, and pyrazinamide, thus compensating for any initial increase in gatifloxacin levels due to a drug interaction. (The OFLOTUB study has been registered at ClinicalTrials.gov under registration no. NCT00216385.).

A semimechanistic pharmacokinetic-enzyme turnover model for rifampin autoinduction in adult tuberculosis patients.

The currently recommended doses of rifampin are believed to be at the lower end of the dose-response curve. Rifampin induces its own metabolism, although the effect of dose on the extent of autoinduction is not known. This study aimed to investigate rifampin autoinduction using a semimechanistic pharmacokinetic-enzyme turnover model. Four different structural basic models were explored to assess whether different scaling methods affected the final covariate selection procedure. Covariates were selected by using a linearized approach. The final model included the allometric scaling of oral clearance and apparent volume of distribution. Although HIV infection was associated with a 30% increase in the apparent volume of distribution, simulations demonstrated that the effect of HIV on rifampin exposure was slight. Model-based simulations showed close-to-maximum induction achieved after 450-mg daily dosing, since negligible increases in oral clearance were observed following the 600-mg/day regimen. Thus, dosing above 600 mg/day is unlikely to result in higher magnitudes of autoinduction. In a typical 55-kg male without HIV infection, the oral clearance, which was 7.76 liters · h⁻¹ at the first dose, increased 1.82- and 1.85-fold at steady state after daily dosing with 450 and 600 mg, respectively. Corresponding reductions of 41 and 42%, respectively, in the area under the concentration-versus-time curve from 0 to 24 h were estimated. The turnover of the inducible process was estimated to have a half-life of approximately 8 days in a typical patient. Assuming 5 half-lives to steady state, this corresponds to a duration of approximately 40 days to reach the induced state for rifampin autoinduction.

PfPI3K, a phosphatidylinositol-3 kinase from Plasmodium falciparum, is exported to the host erythrocyte and is involved in hemoglobin trafficking.

Polyphosphorylated phosphoinositides (PIPs) are potent second messengers, which trigger a wide variety of signaling and trafficking events in most eukaryotic cells. However, the role and metabolism of PIPs in malaria parasite Plasmodium have remained largely unexplored. Our present studies suggest that PfPI3K, a novel phosphatidylinositol-3-kinase (PI3K) in Plasmodium falciparum, is exported to the host erythrocyte by the parasite in an active form. PfPI3K is a versatile enzyme as it can generate various 3'-phosphorylated PIPs. In the parasite, PfPI3K was localized in vesicular compartments near the membrane and in its food vacuole. PI3K inhibitors wortmannin and LY294002 were effective against PfPI3K and were used to study PfPI3K function. We found that PfPI3K is involved in endocytosis from the host and trafficking of hemoglobin in the parasite. The inhibition of PfPI3K resulted in entrapment of hemoglobin in vesicles in the parasite cytoplasm, which prevented its transport to the food vacuole, the site of hemoglobin catabolism. As a result, hemoglobin digestion, which is a source of amino acids necessary for parasite growth, was attenuated and caused the inhibition of parasite growth.

A Differential Response to Antihypertensive Therapy in African Men and Women: Insights From the CREOLE Trial.

BACKGROUND: We sought to address the paucity of data to support the evidence-based management of hypertension to achieve optimal blood pressure (BP) control on a sex-specific basis in Africa. METHODS: We undertook a post hoc analysis of the multicenter, randomized CREOLE (Comparison of Three Combination Therapies in Lowering Blood Pressure in Black Africans) Trial to test the hypothesis that there would be clinically important differences in office BP control between African men and women. We compared the BP levels of 397 and 238 hypertensive women (63%, 50.9 ± 10.5 years) and men (51.2 ± 11.3 years) from 10 sites across sub-Saharan Africa who completed baseline and 6-month profiling according to their randomly allocated antihypertensive treatment. RESULTS: Overall, 442/635 (69.6%) participants achieved an office BP target of <140/90 mm Hg at 6 months; comprising more women (286/72.0%) than men (156/65.5%) (adjusted odds ratio [OR] 1.59, 95% confidence interval [CI] 1.07-2.39; P = 0.023). Women randomized to amlodipine-hydrochlorothiazide (HCTZ) (adjusted OR 3.03, 95% CI 1.71-5.35; P < 0.001) or amlodipine-perindopril (adjusted OR 2.62, 95% CI 1.49-4.58; P = 0.01) were more likely to achieve this target compared with perindopril-HCTZ. Among men, there were no equivalent treatment differences-amlodipine-HCTZ (OR 1.54, 95% CI 0.76-3.12; P = 0.23) or amlodipine-perindopril (OR 1.32, 95% CI 0.65-2.67; P = 0.44) vs. perindopril-HCTZ. Among the 613 participants (97%) with 24-hour ambulatory BP monitoring, women had significantly lower systolic (124.1 ± 18.1 vs. 127.3 ± 16.9; P = 0.028) and diastolic (72.7 ± 10.4 vs. 75.1 ± 10.5; P = 0.007) BP levels at 6 months compared with men. CONCLUSIONS: These data suggest clinically important differences in the therapeutic response to antihypertensive combination therapy among African women compared with African men.

Effect of 3, 2-Drug Combinations of Antihypertensive Therapies on Blood Pressure Variability in Black African Patients: Secondary Analyses of the CREOLE Trial.

BACKGROUND: The effect of 3 commonly recommended combinations of anti-hypertensive agents-amlodipine plus hydrochlorothiazide (calcium channel blocker [CCB]+thiazide), amlodipine plus perindopril (CCB+ACE [angiotensin-converting enzyme]-inhibitor), and perindopril plus hydrochlorothiazide (ACE-inhibitor+thiazide) on blood pressure variability (V) are unknown. METHODS: We calculated the blood pressure variability (BPV) in 405 patients (130, 146, and 129 randomized to ACE-inhibitor+thiazide, CCB+thiazide, and CCB+ACE-inhibitor, respectively) who underwent ambulatory blood pressure monitoring after 6 months of treatment in the Comparisons of Three Combinations Therapies in Lowering Blood Pressure in Black Africans trial (CREOLE) of Black African patients. BPV was calculated using the SD of 30-minute interval values for 24-hour ambulatory BPs and for confirmation using the coefficient of variation. Linear mixed model regression was used to calculate mean differences in BPV between treatment arms. Within-clinic BPV was also calculated from the mean SD and coefficient of variation of 3 readings at clinic visits. RESULTS: Baseline distributions of age, sex, and blood pressure parameters were similar across treatment groups. Participants were predominately male (62.2%) with mean age 50.4 years. Those taking CCB+thiazide had significantly reduced ambulatory systolic and diastolic BPV compared with those taking ACE-inhibitor+thiazide. The CCB+thiazide and CCB+ACE-inhibitor groups showed similar BPV. Similar patterns of BPV were apparent among groups using within-clinic blood pressures and when assessed by coefficient of variation. CONCLUSIONS: Compared with CCB-containing combinations, ACE-inhibitor plus thiazide was associated with higher levels, generally significant, of ambulatory and within-clinic systolic and diastolic BPV. These results supplement the differential ambulatory blood pressure-lowering effects of these therapies in the CREOLE trial.

Actin is required for endocytic trafficking in the malaria parasite Plasmodium falciparum.

The intra-erythrocytic stages of the malaria parasite endocytose large quantities of the surrounding erythrocyte cytoplasm and deliver it to a digestive food vacuole via endocytic vesicles. Digestion provides amino acids for parasite protein synthesis and is required to maintain the osmotic integrity of the host cell. The parasite endocytic pathway has been described morphologically by electron microscopy, but the molecular mechanisms that mediate and regulate it remain elusive. Given the involvement of actin in endocytosis in other eukaryotes, we have used actin inhibitors to assess the requirement for this protein in the endocytic pathway of the human malaria parasite, Plasmodium falciparum. Treatment of cultures with cytochalasin D did not affect haemoglobin levels in the parasites when co-administered with protease inhibitors, and neither did it affect the uptake of the endocytic tracer horseradish peroxidase, suggesting the absence of actin in the mechanism of endocytosis. However, in the absence of protease inhibitors, treated parasites contained increased levels of haemoglobin due to an accumulation of enlarged endocytic vesicles, as determined by immunofluorescence and electron microscopy, suggesting a role for actin in vesicle trafficking, possibly by mediating vesicle maturation and/or fusion to the digestive vacuole. In contrast to cytochalasin D, treatment with jasplakinolide led to an inhibition of endocytosis, an accumulation of vesicles closer to the plasma membrane and a marked concentration of actin in the parasite cortex. We propose that the stabilization of cortical actin filaments by jasplakinolide interferes with normal endocytic vesicle formation and migration from the cell periphery.