Pharmacokinetics of Nevirapine in HIV Infected Children from Resource Limited Settings Using Fixed Dose Anti-retroviral Combinations

Introduction: The pharmacokinetics of nevirapine in paediatric populations are important to consider for those receiving anti-retroviral treatment in resource limited settings. High rate of adherence is required to achieve therapeutic success with good record keeping system for monitoring and follow-ups.

Discussion: Children up to 2 years old have a higher rate of elimination for nevirapine compared to adult population and older children. Elimination rate in children less than 8 years are about twice those in adults. Prescriptions for the drug based on body surface area have been found to be too complex for use in resource limited settings and calculations based on weight bands are used. Though weight bands make drug administration easier the lower weight bands are likely to receive sub therapeutic doses when drug is administered especially when adult fixed dose combinations are used. Chewable paediatric tablets offer better pharmacokinetic profile compared to liquids or oral tablets, however availability of such dosage forms remains low. Solid dosage forms tend to give better nevirapine exposure when taken whole and not broken into halves or quarters as is the case in resource limited settings. Absorption and bioavailability of nevirapine may be affected by nutritional status when they is changes in fat/lean body mass ratio and physiological function due to malnutrition.

Conclusion: Effective antiretroviral treatment is limited by low availability of formulations for nevirapine only or fixed dose combinations for use in paediatric populations. Paediatric formulations are more accurate in achieving trough concentrations and sufficient nevirapine exposure. Adult tablets usually have to be broken in halves or quarters and this can affect the bioavailability of nevirapine and lead to sub therapeutic concentrations.