aDivision of Clinical Pharmacology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Stellenbosch, South Africa;

bDepartment of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Stellenbosch, South Africa; and

cAMS-PHPT Research Collaboration, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.

Correspondence to: Tracy Kellermann, PhD, Office 7031, 7th Floor, Clinical Building, Francie Van Zijl Boulevard, Tygerberg Hospital, P.O. Box 241, Cape Town, 8000, South Africa (e-mail: [email protected]).

The authors have no funding or conflicts of interest to disclose.