HIV Drug Resistance
To the Editor: Clavel and Hance (March 4 issue)1 review resistance to drugs used for the treatment of human immunodeficiency virus infection. Few data are available concerning patterns of antiretroviral-drug resistance among patients in developing countries. However, the fact that the expected virologic success rates of commonly used regimens containing nucleoside reverse-transcriptase inhibitors is approximately 65 percent at 48 weeks is cause for alarm.2
Access to second-line regimens is restricted by their cost, which is currently 10 to 20 times that of first-line regimens. For example, the second-line regimen of tenofovir, didanosine, and either ritonavir or lopinavir, recommended by the World Health Organization, costs up to $6,000 (U.S. dollars) per patient per year.3,4 In the past four years, generic competition has brought the price of first-line drugs down from $10,000 to less than $300 (U.S. dollars) per person per year.5 A similar market situation must be encouraged for second-line medicines.
Moreover, the diagnosis of virologic failure (based on clinical data or the CD4 cell count) is often delayed owing to a lack of affordable and easy-to-use viral-load monitoring. New tools must also be developed to diagnose early virologic failure to control viral replication more efficiently, to improve the clinical outcome, and to prevent the development of resistance to second-line medicines.
Alexandra Calmy, M.D.
Fernando Pascual, Pharm.D.
Nathan Ford, B.Sc.
1. Clavel F, Hance AJ. HIV drug resistance. N Engl J Med 2004;350:1023-1035.
2. Van Leth F, Phanuphak P, Ruxrungtham K, et al. Comparison of first-line antiretroviral therapy with regimens including nevirapine, efavirenz, or both drugs, plus stavudine and lamivudine: a randomised open-label trial, the 2NN Study. Lancet 2004;363:1253-1263.
3. Scaling up antiretroviral therapy in resource-limited settings: treatment guidelines for a public health approach. Geneva: World Health Organization, December 2003.
4. Untangling the web of price reductions: a pricing guide for the purchase of ARVs for developing countries. 5th ed. Geneva: Médecins Sans Frontières, December 2003.
5. von Schoen Angerer T, Wilson D, Ford N, Kasper T. Access and activism: the ethics of providing antiretroviral therapy in developing countries. AIDS 2001;15:Suppl