Effects of Uridine Supplementation on Metabolic Side Effects of Stavudine and Zidovudine

Treatment of HIV infection with nucleoside analogue reverse transcriptase inhibitors (NRTIs) has been associated with numerous toxicities that have been attributed to impaired mitochondrial function secondary to a reduction in the levels of mitochondrial DNA (mtDNA). Abnormalities in mitochondrial function have been implicated in the development of insulin resistance in patients with HIV infection and have also been hypothesized to underlie many of the pathophysiologic features of type 2 diabetes mellitus in non-HIV infected individuals. Uridine, a pyrimidine nucleoside that plays an essential role in the synthesis of RNA and other key physiologic processes, has been proposed as a therapy for NRTI-induced mitochondrial dysfunction. Uridine supplementation protected bone marrow cells from the toxicity of zidovudine, normalized the growth of neurons exposed to NRTIs, and abrogated mitochondrial toxicity of NRTIs in HepG2 cells in vitro. A food supplement called NucleomaxX®, extracted from the stem of sugar cane, raises plasma uridine concentrations to levels known to prevent mitochondrial toxicity in vitro. In a recent case report, oral administration of uridine, given in the form of NucleomaxX®, ameliorated the mitochondrial toxicity caused by stavudine and led to improvements in myalgias and liver and muscle enzymes, despite continuing treatment with stavudine. In a clinical study of 14 HIV-infected patients treated with stavudine or zidovudine, NucleomaxX® led to improved hepatic mitochondrial function as assessed by the 13C-methionine breath test. We will perform a randomized double-blind placebo-controlled study in 20 HIV-positive subjects who are currently undergoing treatment with antiretroviral regimens containing stavudine or zidovudine and who have evidence of impaired mitochondrial function and insulin resistance. Subjects will be hospitalized in the SFGH CTSI Clinical Research Center (CCRC) for 6 days to undergo comprehensive metabolic studies. Subjects will then be randomized, in a 1:1 fashion, to receive either NucleomaxX® or placebo for two months, after which they will repeat the 6-day CCRC-based assessments. This study is designed to test the hypothesis that, in comparison to placebo, uridine supplementation will enhance mitochondrial function, and this will be associated with concomitant improvements in glucose and lipid metabolism.