Zidovudine and Lamivudine for HIV Infection

Abstract

Zidovudine and lamivudine (ZDV and 3TC) are long-standing nucleoside analog-reverse transcriptase inhibitors (NRTIs) with extensive clinical experience in a wide spectrum of patients from in utero through childhood and adult ages. The safety profiles of both drugs are well-known and side effects for ZDV most commonly include nausea/vomiting, fatigue, anemia/neutopenia, and lipoatrophy; while 3TC is well-tolerated. ZDV-3TC is currently a viable alternative NRTI backbone for initial three-drug therapy of HIV infection when tenofovir disoproxil fumarate-emtricitabine (TDF-FTC) cannot be used because of a relative or absolute contraindication. ZDV-3TC continue to be viable alternatives for children, pregnant women and in resource limited settings where other recommended options are not readily available. ZDV-3TC penetrate the Central Nervous System (CNS) well, which makes ZDV-3TC attractive for use in patients with HIV-associated neurological deficits. Additional benefits of these drugs may include the use of ZDV in combination with certain NRTIs to exert selective pressure to prevent particular drug resistance mutations from developing, and giving a short course of ZDV-3TC to prevent resistance after prophylactic single dose nevirapine.

Figure 1

Chemical structures for ZDV and 3TC. From the National Library of Medicine USA.

Figure 2

(1) thymidine kinase I (ZDV) and deoxycytidine kinase (3TC); (2) thymidylate kinase (ZDV) uridylate/cytidylate kinase (3TC); (3) nucleotide diphosphate kinase or 3’ phosphoglycerate kinase; (4) thymidine kinase 2 (ZDV); (5) deoxyribonucleoside monophosphate kinases; (6) nucleoside diphosphate kinase H4; (7) cytosolic 5’-nucleotidase; (8) mitochondrial 5’-nucleotidase. Abbervations: MRP, Multidrug resistance protein; CNT, concentrative nucleoside transporter; mDNC, mitochondrial deoxyribonucleotide carrier; ENT, equilibrative nucleoside transporter.