Paediatric Fixed-dose Combination Research Articles

Paediatric antiretroviral therapy challenges with emerging integrase resistance.

Universal antiretroviral (ART) coverage and virological suppression are fundamental to ending AIDS in children by 2030. Availability of new paediatric dolutegravir (DTG)-based ART formulations is a major breakthrough and will undoubtedly help achieve this goal, but treatment challenges still remain. Paediatric formulations remain limited compared to those for adults, especially for young children, those unable to tolerate DTG or with DTG-based first-line ART failure. Tenofovir alafenamide is virologically superior to standard-of-care backbone drugs in second-line, but paediatric formulations are not widely available. The roles of resistance testing and recycling of backbone drugs following first-line ART failure remain to be determined. Results of trials of novel treatment strategies including dual therapy and long-acting agents are awaited. Although numbers are currently small, safe and effective ART options are urgently required for children developing DTG resistance. The antiretroviral treatment gap between adults and children persists. The potential benefits from rollout of new paediatric DTG-based fixed-dose combination ART for first-line treatment are considerable. However, children remain disadvantaged when DTG-based first-line ART fails or cannot be used. Research efforts to address this inequity require prioritisation in order to ensure health outcomes are optimised for all ages in all settings.

Abacavir Drug Exposures in African Children Under 14 kg Using Pediatric Solid Fixed Dose Combinations According to World Health Organization Weight Bands.

The pharmacokinetics of abacavir (ABC) in African children living with HIV (CLHIV) weighing <14 kg and receiving pediatric fixed dose combinations (FDC) according to WHO weight bands dosing are limited. An ABC population pharmacokinetic model was developed to evaluate ABC exposure across different World Health Organization (WHO) weight bands. Children enrolled in the LIVING study in Kenya and Uganda receiving ABC/lamivudine (3TC) dispersible tablets (60/30 mg) according to WHO weight bands. A population approach was used to determine the pharmacokinetic parameters. Monte Carlo simulations were conducted using an in silico population with demographic characteristics associated with African CLHIV. ABC exposures (AUC0-24) of 6.4-50.4 mg h/L were used as targets. Plasma samples were obtained from 387 children. A 1-compartment model with allometric scaling of clearance (CL/F) and volume of distribution (V/F) according to body weight best characterized the pharmacokinetic data of ABC. The maturation of ABC CL/F was characterized using a sigmoidal Emax model dependent on postnatal age (50% of adult CL/F reached by 0.48 years of age). Exposures to ABC were within the target range for children weighing 6.0-24.9 kg, but children weighing 3-5.9 kg were predicted to be overexposed. Lowering the ABC dosage to 30 mg twice daily or 60 mg once daily for children weighing 3-5.9 kg increased the proportion of children within the target and provided comparable exposures. Further clinical study is required to investigate clinical implications and safety of the proposed alternative ABC doses.

Shorter Treatment for Nonsevere Tuberculosis in African and Indian Children

BackgroundTwo thirds of children with tuberculosis have nonsevere disease, which may be treatable with a shorter regimen than the current 6-month regimen.MethodsWe conducted an open-label, treatment-shortening, noninferiority trial involving children with nonsevere, symptomatic, presumably drug-susceptible, smear-negative tuberculosis in Uganda, Zambia, South Africa, and India. Children younger than 16 years of age were randomly assigned to 4 months (16 weeks) or 6 months (24 weeks) of standard first-line antituberculosis treatment with pediatric fixed-dose combinations as recommended by the World Health Organization. The primary efficacy outcome was unfavorable status (composite of treatment failure [extension, change, or restart of treatment or tuberculosis recurrence], loss to follow-up during treatment, or death) by 72 weeks, with the exclusion of participants who did not complete 4 months of treatment (modified intention-to-treat population). A noninferiority margin of 6 percentage points was used. The primary safety outcome was an adverse event of grade 3 or higher during treatment and up to 30 days after treatment.ResultsFrom July 2016 through July 2018, a total of 1204 children underwent randomization (602 in each group). The median age of the participants was 3.5 years (range, 2 months to 15 years), 52% were male, 11% had human immunodeficiency virus infection, and 14% had bacteriologically confirmed tuberculosis. Retention by 72 weeks was 95%, and adherence to the assigned treatment was 94%. A total of 16 participants (3%) in the 4-month group had a primary-outcome event, as compared with 18 (3%) in the 6-month group (adjusted difference, −0.4 percentage points; 95% confidence interval, −2.2 to 1.5). The noninferiority of 4 months of treatment was consistent across the intention-to-treat, per-protocol, and key secondary analyses, including when the analysis was restricted to the 958 participants (80%) independently adjudicated to have tuberculosis at baseline. A total of 95 participants (8%) had an adverse event of grade 3 or higher, including 15 adverse drug reactions (11 hepatic events, all but 2 of which occurred within the first 8 weeks, when the treatments were the same in the two groups).ConclusionsFour months of antituberculosis treatment was noninferior to 6 months of treatment in children with drug-susceptible, nonsevere, smear-negative tuberculosis. (Funded by the U.K. Medical Research Council and others; SHINE ISRCTN number, ISRCTN63579542.)

Pharmacokinetics of First-Line Drugs in Children With Tuberculosis, Using World Health Organization-Recommended Weight Band Doses and Formulations.

BackgroundDispersible pediatric fixed-dose combination (FDC) tablets delivering higher doses of first-line antituberculosis drugs in World Health Organization–recommended weight bands were introduced in 2015. We report the first pharmacokinetic data for these FDC tablets in Zambian and South African children in the treatment-shortening SHINE trial.MethodsChildren weighing 4.0–7.9, 8.0–11.9, 12.0–15.9, or 16.0–24.9 kg received 1, 2, 3, or 4 tablets daily, respectively (rifampicin/isoniazid/pyrazinamide [75/50/150 mg], with or without 100 mg ethambutol, or rifampicin/isoniazid [75/50 mg]). Children 25.0–36.9 kg received doses recommended for adults <37 kg (300, 150, 800, and 550 mg/d, respectively, for rifampicin, isoniazid, pyrazinamide, and ethambutol). Pharmacokinetics were evaluated after at least 2 weeks of treatment.ResultsIn the 77 children evaluated, the median age (interquartile range) was 3.7 (1.4–6.6) years; 40 (52%) were male and 20 (26%) were human immunodeficiency virus positive. The median area under the concentration-time curve from 0 to 24 hours for rifampicin, isoniazid, pyrazinamide, and ethambutol was 32.5 (interquartile range, 20.1–45.1), 16.7 (9.2–25.9), 317 (263–399), and 9.5 (7.5–11.5) mg⋅h/L, respectively, and lower in children than in adults for rifampicin in the 4.0–7.9-, 8–11.9-, and ≥25-kg weight bands, isoniazid in the 4.0–7.9-kg and ≥25-kg weight bands, and ethambutol in all 5 weight bands. Pyrazinamide exposures were similar to those in adults.ConclusionsRecommended weight band–based FDC doses result in lower drug exposures in children in lower weight bands and in those ≥25 kg (receiving adult doses). Further adjustments to current doses are needed to match current target exposures in adults. The use of ethambutol at the current World Health Organization–recommended doses requires further evaluation.

The Roll-out of Child-friendly Fixed-dose Combination TB Formulations in High-TB-Burden Countries: A Case Study of STEP-TB

Childhood tuberculosis (TB) has hitherto been treated through estimation of pediatric doses through the crushing of adult pills, but the bitter taste of the pills and the inaccuracy of this dosing method presents a challenge for both patients and healthcare providers, leading to poor treatment outcomes. The TB Alliance therefore launched the Speeding Treatments to End Pediatric-Tuberculosis (STEP-TB) project to incentivize the introduction of pediatric Fixed-Dose Combinations (FDCs) of TB drugs. This case study describes the elements of this project, evaluates its impact, and highlights future challenges for pediatric TB treatment. The impact assessment incorporates both market impact as well as projected public health impact, evaluating the availability, affordability, and quality of the FDCs, and lastly providing a projection of lives saved as a result of scale-up of the FDCs to near-universal availability and utilization, based on a publicly available pediatric TB-specific model. STEP-TB resulted in the development of two child-friendly FDCs that were successfully brought to market and made available in 20 of the project’s 22 high-burden countries. On the basis of a country-specific projection of pediatric TB mortality in Kenya, scale-up to near-universal availability and utilization of the new FDCs could reduce pediatric TB-associated mortality by 2660 cases over the next 5 years. Future challenges include maintaining affordable prices for the FDCs and considering mechanisms to incentivize their introduction among high-risk groups in low-burden countries.

Optimization of a paediatric fixed dose combination mini-tablet and dosing regimen for the first line treatment of tuberculosis

We aim to optimize the paediatric dosing regimen of isoniazid, rifampicin and pyrazinamide for the first-line treatment of tuberculosis, based on a fixed dose combination (FDC) mini-tablet using simulations. An optimization problem was set up to determine the 3 strengths of the drugs of the mini-tablet and 4 cutoff points that define the weight bands of a dosing chart, simultaneously. Using Monte Carlo simulations, first, exposure targets were determined for the 3 drugs, from published population pharmacokinetic models for adults, assuming that the approved doses for adults are de facto efficacious. Then optimal strengths and cutoff points were determined by matching children exposures generated from population pharmacokinetic models to the adults targets. The optimal dosing strengths of the FDC tablet were found to be 95 mg of rifampicin, 200 mg of pyrazinamide and 75 mg of isoniazid, and the 4 body weight bands for 1 to 4 mini-tablets, respectively were: 4 to 8 kg, 8 to 12 kg, 12 to 18 kg and 18 to 28 kg. Children with body weight ≥ 28 kg will be treated with adult dosages. The higher doses proposed were evaluated to be much closer to the adult targets compared to the existing recommended by WHO paediatric doses.

Evidence-Based Design of Fixed-Dose Combinations: Principles and Application to Pediatric Anti-Tuberculosis Therapy.

Background and ObjectivesFixed-dose combination formulations where several drugs are included in one tablet are important for the implementation of many long-term multidrug therapies. The selection of optimal dose ratios and tablet content of a fixed-dose combination and the design of individualized dosing regimens is a complex task, requiring multiple simultaneous considerations.MethodsIn this work, a methodology for the rational design of a fixed-dose combination was developed and applied to the case of a three-drug pediatric anti-tuberculosis formulation individualized on body weight. The optimization methodology synthesizes information about the intended use population, the pharmacokinetic properties of the drugs, therapeutic targets, and practical constraints. A utility function is included to penalize deviations from the targets; a sequential estimation procedure was developed for stable estimation of break-points for individualized dosing. The suggested optimized pediatric anti-tuberculosis fixed-dose combination was compared with the recently launched World Health Organization-endorsed formulation.ResultsThe optimized fixed-dose combination included 15, 36, and 16% higher amounts of rifampicin, isoniazid, and pyrazinamide, respectively. The optimized fixed-dose combination is expected to result in overall less deviation from the therapeutic targets based on adult exposure and substantially fewer children with underexposure (below half the target).ConclusionThe development of this design tool can aid the implementation of evidence-based formulations, integrating available knowledge and practical considerations, to optimize drug exposures and thereby treatment outcomes.Electronic supplementary materialThe online version of this article (doi:10.1007/s40262-017-0577-6) contains supplementary material, which is available to authorized users.

A randomized two-way crossover bioequivalence study in healthy adult volunteers of paediatric zidovudine/lamivudine/nevirapine fast-disintegrating fixed-dose combination tablet.

The bioequivalence study was conducted to compare the developed paediatric fixed-dose combination (FDC) zidovudine/lamivudine/nevirapine (60/30/50 mg) tablet - the test formulation - with the combined mixture of single-entity innovator products (reference product). A single-dose open-label randomized two-way crossover study was conducted in healthy adult African volunteers after an informed consent was obtained. The 24 volunteers, divided into two groups, were administered the products after an overnight fast on two treatment days with 14 days of washout period. Blood samples were collected for 96 h and analysed using a validated RP-HPLC-UV assay method. Pharmacokinetic (PK) parameters (non-compartmental model) were assessed with WinNonlin® software. Analysis of variance (ANOVA) and FDA bioequivalence statistical criterion of 90% CI or 80% to 125% range (set at P < 0.05) of least square geometric means (LSGM) ratios of test: reference product for Cmax , AUC0-t , and AUC0-∞ were determined. ANOVA indicated that the period, sequence and formulation had no significant effect on the PK parameters (P > 0.05). The 90% CIs for all the drugs were within the 80% to 125% range. The developed FDC tablet is bioequivalent to the reference product.

Development and in vivo evaluation of child-friendly lopinavir/ritonavir pediatric granules utilizing novel in situ self-assembly nanoparticles

The aim of this study was to develop a nanotechnology to formulate a fixed-dose combination of poorly water-soluble drugs in a children-friendly, flexible solid dosage form. For diseases like HIV, pediatric patients are taking multiple drugs for effective treatments. Fixed-dose combinations could reduce pill burdens and costs as well as improving patient adherence. However, development of fixed-dose combinations of poorly water-soluble drugs for pediatric formulations is very challenging. We discovered a novel nanotechnology that produced in situ self-assembly nanoparticles (ISNPs) when the ISNP granules were introduced to water. In this study, antiretroviral drug granules, including lopinavir (LPV) ISNP granules and a fixed-dose combination of LPV/ritonavir (RTV) ISNP granules, were prepared using the ISNP nanotechnology, which spontaneously produced drug-loaded ISNPs in contact with water. Drug-loaded ISNPs had particle size less than 158nm with mono-dispersed distribution, over 95% entrapment efficiency for both LPV and RTV and stability over 8h in simulated physiological conditions. Drug-loaded ISNP granules with about 16% of LPV and 4% of RTV were palatable and stable at room temperature over 6months. Furthermore, LPV/RTV ISNP granules displayed a 2.56-fold increase in bioavailability and significantly increased LPV concentrations in tested tissues, especially in HIV sanctuary sites, as compared to the commercial LPV/RTV tablet (Kaletra®) in rats. Overall, the results demonstrated that the novel ISNP nanotechnology is a promising platform to manufacture palatable, “heat” stable, and flexible pediatric granules for fixed-dose combinations that can be used as sachets and sprinkles. To the best of our knowledge, this is the first report on this kind of novel nanotechnology for pediatric fixed-dose combinations of poorly water-soluble drugs.

Formulation and Evaluation of Fixed Dose Combination Suppositories Containing Stavudine, Lamivudine and Nevirapine for Pediatric Applications

Suppositories are the convenient way of administering drugs in infants. In view of the lack of suitable pediatric antiretroviral formulations in the market, suppositories containing fixed dose combination (FDC) of stavudine, lamivudine and nevirapine (SLN) were developed to allow administration of the correct weight-related dose in pediatric HIV patients as recommended by WHO. Suppositories containing 10 mg of stavudine, 40 mg of lamivudine and 70 mg of nevirapine were prepared by the fusion method using Witepsol H15 semi-synthetic suppository base. All the prepared suppositories were evaluated for various physical parameters like weight variation, melting point, drug content and hardness. The rate and extent of drug release was evaluated using USP apparatus I and samples were analyzed by a validated UV-multicomponent method. The use of surfactants significantly increased the drug release from formulations manufactured with Witepsol H 15 fatty base. The development of pediatric fixed-dose combination formulations represent a new era and mark an important milestone for children living with HIV/AIDS.

A Randomized Phase I Bioequivalence Clinical Trial of a Paediatric Fixed-Dose Combination Antiretroviral Reconstitutable Suspension in Healthy Adult Volunteers

This study aimed to test the hypothesis that the paediatric fixed-dose combination granule for reconstitution (comprising lamivudine/zidovudine/nevirapine 30/60/50 mg per 5 ml) as a test product is bioequivalent to the coadministered single entities of the referenced products. Fixed-dose combination anti-retroviral therapy provides adequate suppression of HIV-1 replication, provides barrier to the development of resistance, simplifies dosage regimen and improves adherence. An open label, randomized, two-way crossover study was conducted on 24 health adults under fasted conditions, with a washout period of 14 days between treatments. A total of 15 blood samples were collected before dosing and up to 96 h post dosing. The drugs were extracted from plasma and anlaysed using a validated high performance liquid chromatography- ultraviolet method. Non- compartmental pharmacokinetic (PK) analysis was performed to obtain the PK parameters, maximum plasma concentration (C max), area under the curve of plasma concentration-time curves from the time zero to last measurable concentration (AUC0-t) and the area under the curve extrapolated to infinity (AUC 0-∞) ANOVA test was performed to determine the effect of model factors on the PK parameters. The two one-sided t-tests were performed on the log-transformed data to determine the 90% CL for the ratio of test to reference PK parameters. The drugs were well tolerated and safe with minimal adverse events. The ANOVA test indicated the absence of any significant effects ( P>0.05) due to the model parameters. The 90% Cl for the geometric mean ratio of the test/reference for the Cmax, AUC0-t and the AUC0-∞ for lamivudine, zidovudine and nevirapine were within 80-125% bioequivalence limits. This single dose randomized study found that the test and reference products met the criteria for bioequivalence in the fasting healthy adult volunteers.

Pharmacokinetics and Safety of a New Paediatric Fixed-Dose Combination of Zidovudine/Lamivudine/Nevirapine in HIV-Infected Children

Alternatives to the available stavudine-containing paediatric fixed-dose combination (FDC) tablets are rapidly needed due to concerns regarding the cumulative toxicity of long-term stavudine exposure. We report the bioavailability and short-term safety of a novel paediatric FDC tablet of zidovudine (ZDV)/lamivudine (3TC)/nevirapine (NVP; 30/15/28 mg) in HIV-infected children. In this Phase I/II open-label pharmacokinetic study, 42 children weighing 6-30 kg treated with NVP-based HAART for ≥4 weeks were randomized to receive the FDC tablets (GPO-VIR Z30) or the liquid formulations. Dosing was weight-based. Intensive 12-h blood sampling was performed after 2 weeks; subjects then crossed-over to the alternate formulation at equal doses and sampling repeated 2 weeks later. Pharmacokinetic parameters were determined by non-compartmental analysis. Buccal-swab samples were collected for cytochrome P450 (CYP)2B6 polymorphism analysis. With the FDC tablet, the geometric mean (90% CI) area under the curve (AUC) for ZDV, 3TC and NVP was 1.58 (1.49-1.68), 7.78 (7.38-8.19) and 68.88 (62.13-76.36) μg•h/ml, respectively. Rules for NVP therapeutic inadequacy were defined a priori, and despite lower NVP exposure with the tablet (P<0.001), the levels remained therapeutically adequate. ZDV AUC was similar between formulations. 3TC exposure was significantly higher with the tablet but comparable to historical data in adults and children taking branded tablets. While receiving the tablet, NVP AUC in children with CYP2B 516 GG (45%), GT (45%) and TT (10%) genotypes were 67.0, 74.5 and 106.4 μg•h/ml, respectively (P=0.04). Disparities in drug exposure between formulations were observed; however, the FDC tablet delivered therapeutically adequate exposures of each drug and could well play an important role in simplifying antiretroviral treatment for children.

Antiretroviral Drugs in Pediatric HIV-Infected Patients

Antiretroviral (ARV) therapy has been shown to achieve high therapeutic efficacy in treating pediatric HIV disease. The delivery of affordable, child friendly, and easy to store and administer ARV drugs is key to the successful management of HIV in children. In recent years, significant progress has been made in scaling up the access to pediatric ARV therapy among children worldwide. Despite the improved ARV drug access, multiple challenges remain concerning palatability and efficient delivery of ARV drugs to children from infancy into adolescence. Data are limited regarding developmental changes in pharmacokinetics of individual ARV drugs, and pediatric and adult fixed-dose combinations. This review provides a practical discussion regarding the pharmacokinetics of ARV agents in pediatric HIV-infected patients, as well as the practical challenges of currently available formulations, such as palatability of liquid formulations, challenges of crushing tablets, and using adult and pediatric fixed-dose combinations.

Artesunate-mefloquine combination therapy in acute Plasmodium falciparum malaria in young children: a field study regarding neurological and neuropsychiatric safety

BackgroundMefloquine-artesunate combination therapy for uncomplicated falciparum malaria is one of the treatments used in African children. Data concerning neurological safety in adults and children treated with mefloquine and artesunate combination therapy is well documented in Asia. Safety data for neurological and neuropsychiatric side effects of mefloquine and artesunate combination therapy in African children are scarce, although WHO recommends this therapy in Africa.MethodsA phase IV, open label, single arm study was conducted among African children between 10 and 20 kg with acute uncomplicated falciparum malaria. They were treated over three consecutive days with a paediatric fixed-dose combination of artesunate (50 mg/d) and mefloquine (125 mg/d). Parasitological, clinical and neurological examinations and standardized questions about neuropsychiatric symptoms were carried out on days 0, 4, 7, 28 and 63. The primary objective was to assess the neurological and neuropsychiatric safety of artesunate-mefloquine combination therapy in young children.ResultsFrom December 2007 to March 2009, 220 children with uncomplicated Plasmodium falciparum malaria were treated with artesunate and mefloquine. 213 children were analysed according to study protocol. 50 neurological and neuropsychiatric adverse events occurred in 28 patients. Eleven drug-related neurological and neuropsychiatric adverse events occurred in eight patients. Sleeping disorders were present in 2.3%, neurological disorders in 1.4%, neuropsychiatric disorders in 1% and eating disorders in 0.5% of the patients. Adverse events were of mild to moderate intensity and resolved spontaneously.ConclusionAfrican children showed a low percentage of self-limited neurological and neuropsychiatric adverse events, confirming studies on neurological safety in Asian children treated with artesunate and mefloquine. Sleeping disorders were most frequently observed.

The global pediatric antiretroviral market: analyses of product availability and utilization reveal challenges for development of pediatric formulations and HIV/AIDS treatment in children

BackgroundImportant advances in the development and production of quality-certified pediatric antiretroviral (ARV) formulations have recently been made despite significant market disincentives for manufacturers. This progress resulted from lobbying and innovative interventions from HIV/AIDS activists, civil society organizations, and international organizations. Research on uptake and dispersion of these improved products across countries and international organizations has not been conducted but is needed to inform next steps towards improving child health.MethodsWe used information from the World Health Organization Prequalification Programme and the United States Food and Drug Administration to describe trends in quality-certification of pediatric formulations and used 7,989 donor-funded, pediatric ARV purchase transactions from 2002-2009 to measure uptake and dispersion of new pediatric ARV formulations across countries and programs. Prices for new pediatric ARV formulations were compared to alternative dosage forms.ResultsFewer ARV options exist for HIV/AIDS treatment in children than adults. Before 2005, most pediatric ARVs were produced by innovator companies in single-component solid and liquid forms. Five 2-in1 and four 3-in-1 generic pediatric fixed-dose combinations (FDCs) in solid and dispersible forms have been quality-certified since 2005. Most (67%) of these were produced by one quality-certified manufacturer. Uptake of new pediatric FDCs outside of UNITAID is low. UNITAID accounted for 97-100% of 2008-2009 market volume. In total, 33 and 34 countries reported solid or dispersible FDC purchases in 2008 and 2009, respectively, but most purchases were made through UNITAID. Only three Global Fund country recipients reported purchase of these FDCs in 2008. Prices for pediatric FDCs were considerably lower than liquids but typically higher than half of an adult FDC.ConclusionPediatric ARV markets are more fragile than adult markets. Ensuring a long-term supply of quality, well-adapted ARVs for children requires ongoing monitoring and improved understanding of global pediatric markets, including country-based research to explain and address low uptake of new, improved formulations. Continued innovation in pediatric ARV development may be threatened by outdated procurement practices failing to connect clinicians making prescribing decisions, supply chain staff dealing with logistics, donors, international organizations, and pharmaceutical manufacturers. Perceptions of global demand must be better informed by accurate estimates of actual country-level demand.

A Chewable Pediatric Fixed-dose Combination Tablet of Stavudine, Lamivudine, and Nevirapine

Pediatric fixed-dose combinations (FDCs) are needed to facilitate antiretroviral therapy in children. We evaluated the relative bioavailability, safety, and therapeutic adequacy of a novel chewable pediatric FDC tablet of stavudine (7 mg), lamivudine (30 mg), and nevirapine (50 mg), referred to as GPO-VIR S7, and compared it with the individual original brand-name liquid formulations in human immunodeficiency virus-infected Thai children. The International Maternal Pediatric Adolescent AIDS Clinical Trials group (IMPAACT) P1056 study was a phase I/II, 2-arm, randomized, open-label, multidose pharmacokinetic cross-over study. Children ≥6 to ≤30 kg receiving nevirapine-based HAART for at least 4 weeks were randomized to receive GPO-VIR S7 chewable tablets or the equivalent liquid formulations. Children were stratified by weight and dosing was weight-based. Intensive 12-hour blood sampling was performed on day 28, and subjects then crossed-over to the alternate formulation at equal doses with identical 12-hour sampling on day 56. Pharmacokinetic indices were determined by noncompartmental analysis. Thirty-four children completed the study. While taking Government Pharmaceutical Organization (GPO)-VIR S7 the geometric mean (90% CI) area under the curve was 1.54 μg·hr/mL (1.42-1.67) for stavudine, 6.39 (5.82-7.00) for lamivudine, and 74.06 (65.62-83.60) for nevirapine. Nevirapine drug exposure for GPO-VIR S7 was therapeutically adequate. Geometric mean area under the curve ratios (90% CI) of GPO-VIR S7/liquid formulation for stavudine, lamivudine, and nevirapine were 0.97 (0.92-1.02), 1.41 (1.30-1.53), and 1.08 (1.04-1.13), respectively. No serious drug-related toxicity was reported. The chewable FDC was safe and provided therapeutically adequate plasma drug exposures in human immunodeficiency virus-infected children. Substituting the FDC for liquid formulations can simplify antiretroviral therapy.

Limited Sampling Models to Predict the Pharmacokinetics of Nevirapine, Stavudine, and Lamivudine in HIV-Infected Children Treated With Pediatric Fixed-Dose Combination Tablets

Full 12-hour pharmacokinetic profiles of nevirapine, stavudine, and lamivudine in HIV-infected children taking fixed-dose combination antiretroviral tablets have been reported previously by us. Further studies with these formulations could benefit from less-intensive pharmacokinetic sampling. Data from 65 African children were used to relate area under the plasma concentration versus time curve over 12 hours (AUC) to plasma concentrations of nevirapine, stavudine, or lamivudine at times t = 0, 1, 2, 4, 6, 8, and 12 hours after intake using linear regression. Limited sampling models were developed using leave-one-out crossvalidation. The predictive performance of each model was evaluated using the mean relative prediction error (mpe%) as an indicator of bias and the root mean squared relative prediction error (rmse%) as a measure of precision. A priori set criteria to accept a limited sampling model were: 95% confidence limit of the mpe% should include 0, rmse% less than 10%, a high correlation coefficient, and as few (convenient) samples as possible. Using only one sample did not lead to acceptable AUC predictions for stavudine or lamivudine, although the 6-hour sample was acceptable for nevirapine (mpe%: -0.8%, 95% confidence interval: -2.2 to +0.6); rmse%: 5.8%; r: 0.98). Using two samples, AUC predictions for stavudine and lamivudine improved considerably but did not meet the predefined acceptance criteria. Using three samples (1, 2, 6 hours), an accurate and precise limited sampling model for stavudine AUC (mpe%: -0.6%, 95% confidence interval: -2.2 to +1.0; rmse%: 6.5%; r: 0.98) and lamivudine AUC (mpe%: -0.3%, 95% confidence interval: -1.7 to +1.1; rmse%: 5.6%; r: 0.99) was found; this model was also highly accurate and precise for nevirapine AUC (mpe%: -0.2%, 95% confidence interval: -1.0 to +0.7; rmse%: 3.4%; r: 0.99). A limited sampling model using three time points (1, 2, 6 hours) can be used to predict nevirapine, stavudine, and lamivudine AUC accurately and precisely in HIV-infected African children.

A Visual Dosing Aid for First-line Pediatric Antiretroviral Treatment in Resource-poor Settings

The visual dosing aid (VDA) was developed to facilitate dosing calculations in response to children's; growth and weight during antiretroviral treatment. The theoretical accuracy of the VDA was assessed using anthropometric data from 55 children receiving care in the USA and 324 children in the Democratic Republic of the Congo. The VDA dose was similar to the WHO recommended dose. A potentially significant relative dosing difference of >or=20% occurred in <3% of children for NVP, AZT and d4T, but was observed in 20% for 3TC, overdosing being more frequent. The VDA compared well with generic pediatric fixed dose combination tablets. Results did not differ between sites. The VDA enables accurate dosing of pediatric ART in distinct populations and could facilitate roll-out of pediatric ART in resource-poor settings.

Nevirapine, stavudine and lamivudine pharmacokinetics in African children on paediatric fixed-dose combination tablets

Triomune Baby and Junior have been developed in response to the urgent need for appropriate paediatric fixed-dose combination antiretroviral tablets, with higher nevirapine to stavudine and lamivudine ratios than adult tablets, in accordance with paediatric recommendations. We determined whether this ratio results in optimal exposure in the target population. Seventy-one Zambian children were treated with Triomune Baby or Junior dosed according to weight bands. After 4 weeks or more, a 12-h pharmacokinetic curve was recorded. Antiretroviral plasma concentrations were assayed by high-performance liquid chromatography. Six children were excluded because of poor adherence. Of the remaining 65, 24 (37%) were female, 24 (37%) weighed less than 15 kg and most were malnourished. Mean (range) nevirapine C12h, Cmax and AUC12h of 6.0 (1.4, 16.9) mg/l, 10.0 (3.8, 22.5) mg/l and 94.4 (32.1, 232) mg/l per hour were higher than those reported in adults. Nevirapine C12h was subtherapeutic (< 3.0 mg/l) in four children (6%). Mean stavudine and lamivudine C12h, Cmax, AUC12h (< 0.015 mg/l, 0.45 mg/l, 1.05 mg/l per hour and 0.09 mg/l, 1.33 mg/l, 5.42 mg/l per hour) were comparable to adults. There was no evidence of a difference in nevirapine AUC12h across weight bands (P = 0.2), whereas the difference in stavudine (P = 0.0003) and lamivudine AUC12h (P = 0.01) was driven by the single weight band with unequal dosing. Nevirapine concentrations were higher but more variable than in adults; the pharmacokinetic parameters of stavudine and lamivudine were comparable to adults. As nevirapine underdosing is of greater concern than overdosing, the Triomune Baby and Junior ratio appears to be appropriate for children weighing 6 kg and over. Further research is required for children under 6 kg.

A single-dose, randomized, open-label, two-period crossover bioequivalence study of a fixed-dose pediatric combination of lamivudine 40-mg, nevirapine 70-mg, and stavudine 10-mg tablet for oral suspension with individual liquid formulations in healthy adult male volunteers

Background: Because of the lack of suitable pediatric antiretroviral (ARV) agents, adult fixed-dose ARVs are commonly used in children. This practice poses concerns about dose inaccuracy, which may lead to resistance or toxicity. Objective: The objective of the present study was to evaluate the bioequivalence of a new pediatric fixed-dose combination (FDC) ARV tablet for oral suspension as compared with individual liquid formulations. Methods: The FDC ARV tablet for oral suspension contained lamivudine 40 mg, nevirapine 70 mg, and stavudine 10 mg. This formulation was compared with 4 mL of lamivudine 10 mg/mL, 7 mL of nevirapine 50 mg/5 mL, and 10 mL of stavudine 1 mg/mL. This was an open-label, balanced, randomized, 2-treatment, 2-period, 2-sequence, single-dose crossover study in 36 Indian male volunteers under fasting conditions. Blood samples were collected before dosing and at 0.167, 0.25, 0.333, 0.5, 0.667, 0.833, 1, 1.25, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 12, 16, 24, 36, 48, 72, 96, 120, 144, 168, and 192 hours after dosing in each period. Results: The mean (SD) age, weight, and height of the Indian volunteers were 24.78 (5.31) years (range, 18–38 years), 57.06 (8.59) kg (range, 45–77 kg), and 165.14 (5.34) cm (range, 156–176 cm), respectively. The mean (SD) values for T max, C max, and AUC 0-t for the FDC and the individual liquid formulations, respectively, were as follows: lamivudine, 0.71 (0.22) and 0.89 (0.50) hour, 594 (167) and 514 (139) ng/mL, 2382 (617) and 2227 (666) ng /mL per hour; nevirapine, 1.7 (1.1) and 2.5 (1.2) hours, 1248 (275) and 1185 (238) ng/mL, 70,372 (14,869) and 71,278 (17,435) ng/ mL per hour; and stavudine, 0.44 (0.11) and 0.43 (0.11) hour, 348 (82) and 395 (107) ng/mL, and 576 (113) and 631 (142) ng/mL per hour. The ratios and 90% CIs for the least-squares mean Cmax and AUC values were found to be within the prespecified range of 80% to 125% for each component. Conclusion: The FDC pediatric formulation of lamivudine, nevirapine, and stavudine was bioequivalent to the individual liquid formulations in these fasting, healthy Indian men.