To The Editor:
The HIV/AIDS epidemic has already killed an estimated 24 million people, with 40 million currently infected. Potent antiretroviral therapy can significantly improve the clinical course of HIV infection, but its use has been very limited due to its cost. Generic antiretroviral medications are available at a cost as low as 97% less than brand name drugs. 1 Recently, a patient returned to Minneapolis after initiating a course of generic zidovudine (AZT) + 3TC (lamivudine) (Duovir, Cipla) overseas secondary to a possible sexual exposure to HIV. Evaluation revealed adverse effects attributable to the medications and a low risk for HIV transmission so treatment was discontinued.
Because few data have been published regarding the purity of generic antiretroviral medications, an evaluation of the chemical purity of Duovir compared to Combivir (GlaxoSmithKline) was performed at the University of Minnesota Antiviral Pharmacology Laboratory.
One tablet each of Combivir (AZT 300 mg + 3TC 150 mg/capsule; Glaxo-Smith-Kline lot #1ZP2346) and Duovir (AZT 300 mg + 3TC 150 mg/capsule; Cipla lot #C10237) were analyzed for AZT and 3TC content using a procedure derived from United States Pharmacopeia (USP) guidelines for AZT tablets (USP 24-NF19). Solutions from analytical standards and each drug product were independently prepared to achieve final concentrations of 1.25 μg/mL for 3TC and 2.50 μg/mL for AZT. High-performance liquid chromatographic analysis was performed using a validated method for nucleoside analogues. 2 The mean peak areas of the triplicate injections were used for comparison. The tolerance allowed by the USP protocol is 90–110% of the analytical standard target. Combivir was 109 and 95.7%, respectively, and Duovir was 112 and 95.5%, respectively, of target concentrations for 3TC and AZT.
Cipla generic antiretroviral medications are on the World Health Organization list of vital medications. 3 Cipla has offered to sell generic antiretroviral medications to resource poor-countries. 4 The Combivir tablet was within the allowed USP tolerances for both AZT and 3TC. The Duovir tablet was within specification for AZT but slightly beyond the upper tolerance at 112% for 3TC. The difference in results between AZT and 3TC could be due to the preparation of the analytical standard for 3TC or some unknown factor. The cost of a 30-day supply of Duovir is 95% less than the cost of a 30-day supply of Combivir ($34.25 according to the Web site: http://www.cipla.com) vs. $675.69 (at the University-Fairview Pharmacy, respectively). Further studies comparing the purity and pharmacokinetics of generic vs. branded antiretrovirals are important to optimize use of antiretrovirals in resource-poor countries. 5
Keith Henry, MD
Richard Brundage, PhD
Omobosola Akinsete, MD
Anita Shet, MD
1. Binswanger HP. HIV/AIDS treatment for the millions. Science
. 2002: 292:221–223.
2. Kakuda TN, Page LM, Anderson PL, et al. Pharmacologic basis for concentration-controlled therapy with zidovudine, lamivudine, and indinavir. Antimicrob Agents Chemother
3. World Health Organization. Access to HIV/AIDS Drugs and Diagnostics of Acceptable Quality.
3rd ed. 2002.
4. McNeil DG. Indian company offers to supply AIDS drugs at low cost in Africa. New York Times
. February 7, 2002: A10.
5. Theekachunhatean S, Kanthawatana S, Tonsuwannont W, et al. Bioequivalence of a generic preparation of oral zidovudine in healthy Thai volunteers. J Med Assoc Thai
. 1996; 79: 558–562.