Spanish doctors have reported what is believed to be the first case of lactic acidosis attributed to treatment with tenofovir. The case report appears in the September 27 edition of the British Medical Journal.
A 45 year old woman had previously received treatment with ddI, d4T and nevirapine, but that regimen was discontinued due to elevated liver enzymes (the woman had hepatitis C). Liver enzymes normalised, and treatment was resumed with d4T 30mg bid, ddI 250mg qd and tenofovir (300mg qd).
Within days the woman developed vomiting, abdominal pain, confusion and reduced alertness, jaundice and elevated liver enzymes and bilirubin. Her lactic acid levels were 16.38 mmol/l (normal range 0.6-1.7, threshold for discontinuing therapy 5mmol/l).
Antiretroviral treatment was discontinued immediately and bicarbonate, vitamin K, thiamin and riboflavin were given in order to bring the hyperlactatemia under control. Treatment failed, and the woman died 36 hours later.
The authors suggest that because the patient had received prior treatment with ddI and d4T without mishap, the addition of tenofovir was to blame for the development of lactic acidosis. But, in a response to the letter, another Spanish doctor argues that it is more plausible that lactic acidosis was caused by elevated levels of didanosine as a result of the interaction between tenofovir and ddI. In this case, the didanosine dose had been reduced to the recommended 250mg to accommodate the average 40-60% increase in ddI levels seen when the drug is combined with tenofovir.
Further information on this website
HIV-positive man dies of kidney failure and lactic acidosis due to tenofovir/ddI interaction - new story April 8, 2003.
Tenofovir/ddI interaction: pancreatitis death highlights risk - news story, November 23 2002.
Tenofovir - drug overview.
Rivas P et al. Drug points: Fatal lactic acidosis associated with tenofovir. British Medical Journal 327: 711, 2003.