Incidence and determinants of adverse events in individuals with HIV commencing Dolutegravir-based antiretroviral therapy in mainland Tanzania

Tanzania adopted a Dolutegravir (DTG)-based regimen as first-line treatment in 2019 following the World Health Organization recommendation. Data on the DTG safety profile from sub-Saharan Africa including Tanzania are limited. We investigated the incidence of DTG-related adverse events (AEs) and associated factors among people living with HIV (PLHIV) initiated on a DTG regimen. A prospective cohort study was conducted from 25 Care and Treatment Clinics in mainland Tanzania. PLHIV aged 12 years and above who were initiated on a DTG-based regimen were actively followed up for three months. The Cox regression model was used to determine the predictors of occurrence of AEs over time. A p-value of 0.05 was considered statistically significant. From January 2020 to June 2022, a cohort of 935 participants who were both newly diagnosed and ART-experienced who transitioned to a DTG-based regimen was enrolled. Out of 935 participants, 59 (6.3%) reported a total of 62 AEs. The most frequently experienced AE was skin itching and rashes (15/62; 24.2%). DTG-associated neuropsychiatric AEs were less common and included headache (6 [9.6%]) and sleep disturbances (3 [4.8%]). The overall incidence of occurrence of the first AEs was 96.7 per 1000 person-months [95% C.I: 74.4-125.7] with the highest incidence observed among the elderly (≥ 60 years). Individuals on WHO HIV Clinical Stage 2 had a 2.7 significantly higher risk of developing AEs (adjusted hazard ratio = 2.73, 95% CI = 1.46-5.12, p = 0.017). We report a low incidence of grade I (mild) and grade II (moderate) DTG-associated AEs suggesting that the regimen is generally safe in the population. Continued monitoring of DTG safety in the population is recommended.

Population pharmacokinetics of ivermectin after mass drug administration in lymphatic filariasis endemic communities of Tanzania

Ivermectin (IVM) is a drug of choice used with albendazole for mass drug administration (MDA) to halt transmission of lymphatic filariasis. We investigated IVM pharmacokinetic (PK) variability for its dose optimization during MDA. PK samples were collected at 0, 2, 4, and 6 h from individuals weighing greater than 15 kg (n = 468) receiving IVM (3-, 6-, 9-, or 12 mg) and ALB (400 mg) during an MDA campaign in Tanzania. Individual characteristics, including demographics, laboratory/clinical parameters, and pharmacogenetic variations were assessed. IVM plasma concentrations were quantified by liquid-chromatography tandem mass spectrometry and analyzed using population-(PopPK) modeling. A two-compartment model with transit absorption kinetics, and allometrically scaled oral clearance (CL/F) and central volume (Vc /F) was adapted. Fitting of the model to the data identified 48% higher bioavailability for the 3 mg dose compared to higher doses and identified a subpopulation with 97% higher mean transit time (MTT). The final estimates for CL/F, Vc /F, intercompartment clearance, peripheral volume, MTT, and absorption rate constant for a 70 kg person (on dose other than 3 mg) were 7.7 L/h, 147 L, 20.4 L/h, 207 L, 1.5 h, and 0.71/h, respectively. Monte-Carlo simulations indicated that weight-based dosing provides comparable exposure across weight bands, but height-based dosing with capping IVM dose at 12 mg for individuals with height greater than 160 cm underdoses those weighing greater than 70 kg. Variability in IVM PKs is partly explained by body weight and dose. The established PopPK model can be used for IVM dose optimization. Height-based pole dosing results in varying IVM exposure in different weight bands, hence using weighing scales for IVM dosing during MDA is recommended.

Effect of pharmacogenetic variations on praziquantel plasma concentration and safety outcomes among school children in Rwanda

School-based mass drug administration (MDA) of Praziquantel (PZQ) is the global intervention strategy for elimination of schistosomiasis. Genetic variations in drug metabolizing enzymes and transporter proteins influences drug exposure and treatment outcomes, but data on PZQ pharmacokinetics and safety outcomes are scarce. We investigated the effect of pharmacogenetics variations on PZQ plasma concentrations and safety outcomes among 462 Rwandan schoolchildren who received single dose PZQ and albendazole in MDA. Genotyping for common functional variant alleles CYP3A4*1B, CYP3A5 (*3, *6, *7), CYP2C19 (*2, *3, *17), CYP2C9 (*2, *3) and CYP2J2*7 were done. Plasma concentration of PZQ, cis-4-OH-PZQ and trans-4-OH-PZQ were measured using LC/MS/MS. Active safety monitoring was done on days 1, 2, and 7 post-MDA. CYP2C9 and CYP2C19 genotypes were significantly associated with PZQ plasma concentrations and its cis- and trans-4-OH-PZQ/PZQ metabolic ratios (MR). CYP2C9*2 and CYP2C9*3 carriers had significantly higher PZQ concentration (p = 0.02), lower trans-4-OH-PZQ/PZQ (p < 0.001), and cis-4-OH-PZQ/PZQ (p = 0.02) MR. CYP2C19 (*2, *3) carriers had significantly higher plasma PZQ concentration than CYP2C19 *1/*1 and CYP2C19 *17 carriers (*1/*17 or *17/*17) (p < 0.001). CYP3A4 was significantly associated with cis-4-OH-PZQ MR (p = 0.04). Lower cis-4-OH-PZQ/PZQ MR (p < 0.0001) was a predictor of MDA-associated adverse events, but no significant association with genotypes were found. In conclusion, CYP2C9 and CYP2C19 genotypes significantly influence the plasma PZQ concentration and its MR. Lower cis-4-OH-PZQ/PZQ MR is significant predictor of adverse events following MDA.

Effect of Pharmacogenetics Variations on Praziquantel Plasma Concentrations and Schistosomiasis Treatment Outcomes Among Infected School-Aged Children in Tanzania

Studies on pharmacogenetics of praziquantel (PZQ) and its relevance on plasma drug concentrations and schistosomiasis treatment outcomes are lacking. We investigated the effect of pharmacogenetics variations of PZQ on plasma drug levels and schistosomiasis treatment outcomes among infected Tanzanian school-aged children. A total of 340 Schistosoma mansoni infected children were enrolled and treated with single-dose PZQ. Stool samples analysis was done by thick smear Kato-Katz technique, and treatment efficacy was assessed at 3-weeks post-treatment. Safety was assessed within 4 h after PZQ intake. Plasma samples were collected at 4 h post-dose, and PZQ and trans-4-OH-PZQ concentrations were quantified using UPLCMS/MS. Genotyping for CYP3A4*1B, CYP3A5 (*3, *6, *7), CYP2C19 (*2, *3, *17), and CYP2C9 (*2, *3) were done by Real-Time PCR. The median age (range) of the study participants was 12 years (7-17). There was a significant association of CYP2C19 genotypes with PZQ concentrations and its metabolic ratio (trans-4-OH-PZQ/PZQ). PZQ concentration was significantly higher among CYP2C19 (*2, *3) carriers than CYP2C19 *1/*1 and CYP2C19 *17 carriers (ultra-rapid metabolizers) (p = 0.04). The metabolic ratio was significantly higher among CYP2C19*17 carriers than CYP2C19 (*2, *3) carriers (p = 0.01). No significant effect of CYP3A4, CYP3A5, CYP2C19, and CYP2C9 genotypes on treatment efficacy or adverse events were observed. Baseline infection intensity and CYP3A5 genotype were significant predictors of treatment associated-adverse events. In conclusion, CYP2C19 genotype significantly affects plasma PZQ concentration and its metabolic ratio. For the first time, we report the importance of pharmacogenetic variation for the treatment of schistosomiasis, a neglected tropical disease.

Effect of Dihydroartemisinin-Piperaquine on the Pharmacokinetics of Praziquantel for Treatment of Schistosoma mansoni Infection

Praziquantel (PZQ) and dihydroartemisinin-piperaquine (DHP) combination recently showed superior effectiveness than PZQ alone to treat intestinal schistosomiasis. In this follow-up study, we investigated the effect of DHP co-administration on the pharmacokinetics of PZQ and its enantiomers among 64 Schistosoma mansoni infected children treated with PZQ alone (n = 32) or PZQ + DHP combination (n = 32). Plasma samples collected at 0, 1, 2, 4, 6, and 8 h post-dose were quantified using UPLCMS/MS. The geometric mean (GM) of AUCs for total PZQ, R-PZQ and S-PZQ were significantly higher among children who received PZQ + DHP than PZQ alone. The geometric mean ratio (GMR) and (90% CI) of AUC_0–∞ for PZQ + DHP to PZQ for total PZQ, R-PZQ, and S-PZQ were 2.18 (1.27, 3.76), 3.98 (2.27, 7.0) and 1.86 (1.06, 3.28), respectively. The GMR and (90% CI) of AUC_0–8 for total PZQ, R-PZQ, and S-PZQ were 1.73 (1.12, 2.69), 2.94 (1.75, 4.92), and 1.50 (0.97, 2.31), respectively. The GM of C_max for total PZQ, R-PZQ and S-PZQ were significantly higher among those who received PZQ + DHP than PZQ alone. The GMR (90% CI) of C_max of PZQ + DHP to PZQ for total PZQ, R-PZQ, and S-PZQ were 1.75 (1.15, 2.65), 3.08 (1.91, 4.96), and 1.50 (1.0, 2.25%), respectively. The 90% CI of the GMRs for both AUCs and C_max for total PZQ, R-PZQ, and S-PZQ were outside the acceptable 0.80–1.25 range, indicating that the two treatment arms were not bioequivalent. DHP co-administration significantly increases systemic PZQ exposure, and this may contribute to increased effectiveness of PZQ + DHP combination therapy than PZQ alone to treat schistosomiasis.

Efficacy and safety of praziquantel and dihydroartemisinin piperaquine combination for treatment and control of intestinal schistosomiasis: A randomized, non-inferiority clinical trial

BACKGROUND

Despite the reported success in reducing morbidity, praziquantel alone is insufficient for the control and elimination of schistosomiasis, partly due to its poor efficacy against the juvenile worms. Artemisinin derivatives are effective against juvenile worms but are less effective against adult worms. We compared the safety and efficacy of praziquantel and Dihydroartemisinin-piperaquine combination against the standard praziquantel alone for treatment of intestinal schistosomiasis.

METHODS

In this randomized, open-label, non-inferiority trial, 639 Schistosoma mansoni infected children were enrolled and randomized to receive either praziquantel alone or praziquantel plus Dihydroartemisinin-piperaquine combination. Two stool samples were collected on consecutive days at baseline, 3 and 8 weeks post-treatment and analyzed using thick smear Kato Katz method. Efficacy was assessed by cure and egg reduction rates at 3 and 8 weeks post-treatment. Adverse events were assessed within four hours of drugs intake. The primary outcome was cure rates at 8 weeks of post-treatment. Secondary outcomes were egg reduction rates at 8 weeks of post-treatment and treatment-associated adverse events.

RESULTS

At 3 weeks of post-treatment, cure rates were 88.3% (263/298, 95% CI = 84.1%- 91.4%) and 81.2% (277/341, 95% CI = 76.7%- 85.0%) for the combination therapy and praziquantel alone, respectively (p < 0.01, odds ratio (OR) = 1.74, 95% CI of OR = 1.11 to 2.69). At 8 weeks, there was a significant drop in the cure rates in praziquantel alone group to 63.9% (218/341, 95% CI = 58.7%- 68.8%) compared to 81.9% (244/298, 95% CI = 77.1%- 85.8%) in the combination therapy group (p < 0.0001, OR = 2.55, 95%CI of OR = 1.75 to 3.69). Egg reduction rates at 8 weeks post-treatment were significantly higher in the combination therapy group 93.6% (95% CI = 90.8%- 96.4%) compared to 87.9% (95% CI = 84.4%- 91.4%) in the praziquantel only group (p = 0.01). On both Univariate and Multivariate regression analysis, type of treatment received was a significant predictor of cure at week 8 post-treatment. Overall, 30.8% (95% CI = 27.2%- 34.4%) of the study participants experienced mild and transient treatment-associated adverse events, post-treatment abdominal pain (27.1%) being the most common adverse event observed. There was no significant difference in the overall occurrence of adverse events between the two treatment groups.

CONCLUSION

Praziquantel and Dihydroartemisinin piperaquine combination therapy is safe, and more efficacious compared to praziquantel alone for the treatment of intestinal schistosomiasis. Further studies are needed to explore if the combination therapy can be considered as an option for mass drug administration to control and eventually eliminate schistosomiasis.

Prevalence and correlates of intestinal schistosomiasis infection among school-aged children in North-Western Tanzania

BACKGROUND

Schistosomiasis is a neglected tropical disease that continues to cause morbidity and mortality in Sub Saharan Africa. Due to its endemicity, co-infection with malaria is common. The diseases cause anaemia and impaired nutritional status among children. We investigated the prevalence of intestinal schistosomiasis and its association with malaria, anaemia and nutritional status among school children.

METHODS

This was a cross sectional survey among 830 children in Nyamikoma village along Lake Victoria in Tanzania. A pre-tested questionnaire was used to collect socio-demographic data, history of drug use, and clinical data. Two faecal samples were collected on two consecutive days and analyzed using thick smears Kato Katz method. Diagnosis of malaria was done by malaria rapid diagnostic test, and haemoglobin concentration was determined using HemoCue. Nutritional status was assessed by anthropometric measurements.

RESULTS

The overall prevalence of intestinal schistosomiasis was 90.6% (95% CI = 88.6% - 92.6%). Intensity of infection was light 24.1% (200/830), moderate 38.4% (319/830) and heavy 28.1% (233/830). Pre-adolescents (≤12 years) were more infected with intestinal schistosomiasis (93.2%) than adolescents (>12 years) (84.7%) (p < 0.001). Prevalence of malaria was 1.7% (14/824), and that of intestinal schistosomiasis-malaria co-infection was 1.6% (13/824). The overall prevalence of anaemia was 24.6% (95%CI = 18.7% - 30.5%). Severe anaemia was found in 2.3% (19/824) of study participants. The prevalence of stunting and wasting were 29.0% and 11.3%, respectively. On both univariate and multivariate regression analysis, only lower age was significantly associated intestinal schistosomiasis infection, but not anemia, malaria, stunting or wasting. However among those infected, a negative binomial regression analysis indicated independent significant association of male sex, loose stool consistency, and stunting with high eggs count/gram of stool.

CONCLUSIONS

Despite several rounds of annual mass praziquantel administration, intestinal schistosomiasis is highly prevalent among school children particularly in younger children living in the study area. Biannual targeted mass praziquantel treatments or alternative regimens may be considered in future in the study area to redress the situation.