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

  • N L Katende-Kyenda
  • M S Lubbe
  • J H Serfontein
  • I Truter


Objectives. Human immunodeficiency 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 a national medicine claims database for the period 1 January to 31 December 2004. Setting. A section of the private health care sector in South Africa. Subjects. All ARV prescriptions (N=43 482) claimed during 2004. The possible DDIs found were classified according to a clinical significance rating described by Tatro (2005) in his book Drug Interaction Facts. Results. A total of 5 305 882 medicine items were prescribed; of these, 1.92% (N=101 938) were ARVs. Of the total number of 2 595 254 prescriptions, 1.68% (N=43 482) contained ARVs. A total number of 18 035 DDIs (81 different types) were identified; of these, 83.89% (N=15 130) were DDIs between ARVs and other drugs, while 16.11% (N=2 905) were DDIs between ARVs themselves. Possible DDIs with a clinical significance level of 1 (major, N=17) and 2 (moderate, N=1 436) 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 need to understand and anticipate these DDIs and to overcome them by dose adjustments and patient education, so that they are not life threatening to HIV/AIDS patients.

South African Medical Journal Vol. 98 (2) 2008: pp. 109-113

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