14 March 2018

In Clinical Pharmacokinetics Stein Schalkwijk, Rob ter Heine, Angela Colbers and David Burger, described the feasibility to reduce the efavirenz dose in HIV-positive pregnant women to minimize treatment costs and limit toxicity.​


Reducing the dose of efavirenz can improve safety, reduce costs, and increase access for patients with HIV infection. According to the World Health Organization, a similar dosing strategy for all patient populations is desirable for universal roll-out; however, it remains unknown whether the 400 mg daily dose is adequate during pregnancy.


We developed a mechanistic population pharmacokinetic model using pooled data from women included in seven studies (1968 samples, 774 collected during pregnancy). Total and free efavirenz exposure (AUC24 and C12) were predicted for 400 (reduced) and 600 mg (standard) doses in both pregnant and non-pregnant women.


Using a 400 mg dose, the median efavirenz total AUC24 and C12 during the third trimester of pregnancy were 91 and 87% of values among non-pregnant women, respectively. Furthermore, the median free efavirenz C12 and AUC24 were predicted to increase during pregnancy by 11 and 15%, respectively.


It was predicted that reduced-dose efavirenz provides adequate exposure during pregnancy. These findings warrant prospective confirmation.

Stein Schalkwijk, Rob ter Heine, Angela Colbers and David Burger are members within the theme Infectious diseases and global health.
A Mechanism-Based Population Pharmacokinetic Analysis Assessing the Feasibility of Efavirenz Dose Reduction to 400 mg in Pregnant Women. Schalkwijk S, Ter Heine R, Colbers AC, Huitema ADR, Denti P, Dooley KE, Capparelli E, Best BM, Cressey TR, Greupink R, Russel FGM, Mirochnick M, Burger DM. Clin Pharmacokinet. 2018 Mar 8. doi: 10.1007/s40262-018-0642-9.

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