Original articles

Prevalence of drug-drug interactions of antiretroviral agents in the private health care sector in South Africa

Norah Lucky Katende-Kyenda, M S Lubbe, J H P Serfontein, I Truter


Human immunodefiency virus (HIV) infection can be effectively treated with highly active antiretroviral therapy (HAART), requiring concomitant administration of three to four different agents, often with a high potential for drug-drug interactions (DDIs). This study aimed to determine the prevalence of possible DDIs between antiretrovirals (ARVs) themselves and other drugs.

Design. Retrospective drug-utilisation study using data from from a national medicine claims database for the period 1 January to 31 December 2004.

Setting. A section of the private healthcare sector in South Africa.

Subjects. All ARV prescriptions (N=43482) claimed during 2004. The possible DDIs found were classified according to a clinical significant rating as described by Tatro7 (2005) in his book, “Drug Interactions – Facts and comparisons.”

Results. A total of 5305882 medicine items were prescribed, of these, 1.92% (N=101 938) accounted for ARVs. Of the total number of 2595254 prescriptions, 1.68% (N=43 482), were ARVs. A total number of 18035 DDIs (81 different types) were identified, of these, 83.89%, (n=15130) were DDIs between ARVs and other drugs, while 16.11% (n=2905) were DDIs between ARVs themselves. Possible DDIs with a clinical significance level of 1 (major, n=17) and 2 (moderate, n=1436) represented 8.06% (n=1 453) of the total number of identified interactions.

Conclusions. Since concomitant use of ARVs and other drugs used to treat HIV complications is increasing, there is a great need of understanding and anticipating these DDIs, overcoming them by dose adjustments and patient education by pharmacists, so that they are not life threatening to HIV/AIDS patients.

Authors' affiliations

Norah Lucky Katende-Kyenda, SA Pharmacy Council

M S Lubbe,

J H P Serfontein,

I Truter,

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Drug-drug interactions, Antiretroviral agents

Cite this article

South African Medical Journal 2008;98(2):109.

Article History

Date submitted: 2007-07-12
Date published: 2008-02-11

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