Case Report: Is it safe to switch from stavudine to zidovudine after developing symptomatic hyperlactatemia?

Introduction: The prognosis of Ugandan patients with HIV infection has improved with increased access to free antiretroviral therapy (ART). The first-line combination therapy recommended by the National Guidelines includes zidovudine or stavudine plus lamivudine, in combination with either nevirapine or efavirenz 1 . Stavudine 2-4 and to a much lesser extent zidovudine 5 use is associated with type B lactic acidosis (without hypoxemia). Because most of patients are started on stavudine containing regimens, this rare, but potentially fatal syndrome has become of great concern in resource limited settings (RLS) 6-7 . Both diagnosis and management of this condition are difficult, leading to high mortality among patients (7- 21%) 6, 7 . The treatment of lactic acidosis/symptomatic hyperlactatemia is supportive (intravenous fluids, mechanical ventilation, and dialysis) and presumed causative drugs should be discontinued and substituted with a nucleoside reverse transcriptase inhibitors (NRTI) less likely to cause this syndrome such as tenofovir and abacavir. However these agents are expensive and often not available in RLS. Therefore patients who develop stavudine induced hyperlactatemia are often switched to zidovudine on the basis of published studies 8, 9 that demonstrate that this agent can be a safe alternative.Recently however, we observed a case of relapse of symptomatic hyperlactatemia in a patient that was switched from stavudine to zidovudine.