Pharmacokinetic (PK) studies in children are usually small and have ethical constraints due to the medical complexities of drawing blood in this special population. Often, population PK models for the drug(s) of interest are available in adults, and these models can be extended to incorporate the expected deviations seen in children. As a consequence, there is increasing interest in the use of optimal design methodology to design PK sampling schemes in children that maximize information using a small sample size and limited number of sampling times per dosing period. As a case study, we use the novel tuberculosis drug delamanid, and show how applications of optimal design methodology can result in highly efficient and model-robust designs in children for estimating PK parameters using a limited number of sampling measurements. Using developed population PK models based on available data from adults living with and without HIV, and limited data on children without HIV, competing designs for children living with HIV were derived and assessed based on robustness to model uncertainty.

Background

Human immunodeficiency virus (HIV)-infected children receiving antiretroviral therapy (ART) have increased prevalence of hyperlipidemia and risk factors for cardiovascular disease. No studies have investigated the efficacy and safety of statins in this population.

Methods

HIV-infected youth 10 to <24 years of age on stable ART with low-density lipoprotein cholesterol (LDL-C) ≥130 mg/dL for ≥6 months initiated atorvastatin 10 mg once daily. Atorvastatin was increased to 20 mg if LDL-C efficacy criteria (LDL-C < 110 mg/dL or decreased ≥30% from baseline) were not met at week 4. Primary outcomes were safety and efficacy.

Results

Twenty-eight youth initiated atorvastatin; 7 were 10-15 years and 21 were 15-24 years. Mean baseline LDL-C was 161 mg/dL (standard deviation 19 mg/dL). Efficacy criteria were met at week 4 by 17 of 27 (63%) participants. Atorvastatin was increased to 20 mg in 10 participants. Mean LDL-C decreased from baseline by 30% (90% confidence interval: 26%, 35%) at week 4, 28% (90% confidence interval: 23%, 33%) at week 24 and 26% (90% confidence interval: 20%, 33%) at week 48. LDL-C was less than 110 mg/dL in 44% at week 4, 42% at week 12 and 46% at weeks 24 and 48. Total cholesterol, non high-density lipoprotein (non-HDL)-C and apolipoprotein B decreased significantly, but IL-6 and high-sensitivity C-reactive protein did not. Two participants in the younger age group discontinued study for toxicities possibly related to atorvastatin.

Conclusions

Atorvastatin lowered total cholesterol, LDL-C, non HDL-C and apolipoprotein B in HIV-infected youth with ART-associated hyperlipidemia. Atorvastatin could be considered for HIV-infected children with hyperlipidemia, but safety monitoring is important particularly in younger children.

Background

Human immunodeficiency virus (HIV)-infected children receiving antiretroviral therapy (ART) have increased prevalence of hyperlipidemia and risk factors for cardiovascular disease. No studies have investigated the efficacy and safety of statins in this population.

Methods

HIV-infected youth 10 to <24 years of age on stable ART with low-density lipoprotein cholesterol (LDL-C) ≥130 mg/dL for ≥6 months initiated atorvastatin 10 mg once daily. Atorvastatin was increased to 20 mg if LDL-C efficacy criteria (LDL-C < 110 mg/dL or decreased ≥30% from baseline) were not met at week 4. Primary outcomes were safety and efficacy.

Results

Twenty-eight youth initiated atorvastatin; 7 were 10-15 years and 21 were 15-24 years. Mean baseline LDL-C was 161 mg/dL (standard deviation 19 mg/dL). Efficacy criteria were met at week 4 by 17 of 27 (63%) participants. Atorvastatin was increased to 20 mg in 10 participants. Mean LDL-C decreased from baseline by 30% (90% confidence interval: 26%, 35%) at week 4, 28% (90% confidence interval: 23%, 33%) at week 24 and 26% (90% confidence interval: 20%, 33%) at week 48. LDL-C was less than 110 mg/dL in 44% at week 4, 42% at week 12 and 46% at weeks 24 and 48. Total cholesterol, non high-density lipoprotein (non-HDL)-C and apolipoprotein B decreased significantly, but IL-6 and high-sensitivity C-reactive protein did not. Two participants in the younger age group discontinued study for toxicities possibly related to atorvastatin.

Conclusions

Atorvastatin lowered total cholesterol, LDL-C, non HDL-C and apolipoprotein B in HIV-infected youth with ART-associated hyperlipidemia. Atorvastatin could be considered for HIV-infected children with hyperlipidemia, but safety monitoring is important particularly in younger children.

Tuberculosis is a major cause of morbidity and mortality in women of childbearing age (15-44 years). Despite increased tuberculosis risk during pregnancy, optimal clinical treatment remains unclear: safety, tolerability, and pharmacokinetic data for many tuberculosis drugs are lacking, and trials of promising new tuberculosis drugs exclude pregnant women. To advance inclusion of pregnant and postpartum women in tuberculosis drug trials, the US National Institutes of Health convened an international expert panel. Discussions generated consensus statements (>75% agreement among panelists) identifying high-priority research areas during pregnancy, including: (1) preventing progression of latent tuberculosis infection, especially in women coinfected with human immunodeficiency virus; (2) evaluating new agents/regimens for treatment of multidrug-resistant tuberculosis; and (3) evaluating safety, tolerability and pharmacokinetics of tuberculosis drugs already in use during pregnancy and postpartum. Incorporating pregnant women into clinical trials would extend evidence-based tuberculosis prevention and treatment standards to this special population.

Background

Pregnancy increases the risk of tuberculosis and its complications. A 3-month regimen of weekly isoniazid and rifapentine (3HP) is safe and effective for tuberculosis prevention in adults and children, including those with HIV, but 3HP has not been evaluated in pregnancy.

Methods

IMPAACT 2001 was a phase I/II trial evaluating the pharmacokinetics and safety of 3HP among pregnant women with indications for tuberculosis preventative therapy in Haiti, Kenya, Malawi, Thailand, and Zimbabwe (NCT02651259). Isoniazid and rifapentine were provided at standard doses (900 mg/week). Pharmacokinetic sampling was performed with the first (second/third trimester) and twelfth (third trimester/postpartum) doses. Nonlinear mixed-effects models were used to estimate drug population pharmacokinetics.

Results

Of 50 participants, 20 had HIV and were taking efavirenz-based antiretroviral therapy. Among women without HIV, clearance of rifapentine was 28% lower during pregnancy than postpartum (1.20 vs 1.53 L/hour, P < .001), with area under the concentration-time curve (AUCSS) of 786 and 673 mg × hour/L, respectively. In pregnant women with HIV, clearance was 30% higher than women without HIV (P < .001), resulting in lower AUCss (522 mg × hour/L); clearance did not change significantly between pregnancy and postpartum. Pregnancy did not impact isoniazid pharmacokinetics. There were no drug-related serious adverse events, treatment discontinuations, or tuberculosis cases in women or infants.

Conclusions

3HP does not require dose adjustment in pregnancy. Rifapentine clearance is higher among women with HIV, but all women achieved exposures of rifapentine and isoniazid associated with successful tuberculosis prevention. The data support proceeding with larger safety-focused studies of 3HP in pregnancy.

Clinical trials registration

ClinicalTrials.gov, NCT02651259.