Research Articles >
College of Health Sciences >
Please use this identifier to cite or link to this item:
|Title: ||Population pharmacokinetics of efavirenz in HIV and TB/HIV coinfected children: the significance of genotype-guided dosing|
|Authors: ||Alghamdi, Wael A.|
Peloquin, Charles A.
|Issue Date: ||2019|
|Publisher: ||J Antimicrob Chemother|
|Abstract: ||The current WHO weight-based dosing recommendations for efavirenz result in a wide variability of
drug exposure in children. Our objectives are to characterize the effects of rifampicin- and isoniazid-containing
anti-TB therapy and CYP2B6 activity on efavirenz concentrations in children, using non-linear mixed-effects
Methods: This is a pharmacokinetic (PK) substudy of a prospective study that examined the interactions between
anti-TB therapy and efavirenz in HIV-infected children with and without TB. PK samples were obtained
4 weeks after starting efavirenz (PK1) and repeated 4 weeks after completing TB therapy (PK2) in TB/HIV
coinfected patients. Drug concentrations were measured using LC-MS/MS. Composite CYP2B6 516/983/15582
genotype was determined. Population PK modelling was performed in Monolix. Simulations were performed to
obtain the predicted mid-dose concentrations (C12).
Results: One hundred and five HIV-infected Ghanaian children (46 with TB/HIV) were included. The median age
and weight were 7 years and 19 kg. The efavirenz concentrations over time were adequately described using a
one-compartment model. Weight, composite CYP2B6 genotype and PK visit had a significant influence on the
PK parameters, while TB therapy had no significant effect. Simulations showed adequate C12 for intermediate
composite CYP2B6 metabolizers only.
Conclusions: Our model showed that rifampicin- and isoniazid-containing anti-TB therapy does not influence
efavirenz PK parameters. On the other hand, it describes the effect of efavirenz autoinduction after completing
TB treatment. In addition, dosing efavirenz in children based only on weight results in a large variability in drug
exposure.We propose dose adjustments for slow and extensive composite CYP2B6 metabolizers.|
|Description: ||This article is published in J Antimicrob Chemother and also available at doi:10.1093/jac/dkz238|
|Appears in Collections:||College of Health Sciences|
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.