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Issue No. 18 | April 27, 2012

News and Features

FDA Issues Safety Announcement with Updated Information on Drug Interactions Between Boceprevir (Victrelis) and Certain Ritonavir-Boosted HIV Protease Inhibitor Drugs

“The U.S. Food and Drug Administration (FDA) is notifying the public that co-administration of Victrelis (boceprevir), a hepatitis C virus (HCV) protease inhibitor, along with certain ritonavir-boosted human immunodeficiency virus (HIV) protease inhibitors, is not recommended at this time because of the possibility of reducing the effectiveness of the medicines, permitting the amount of HCV or HIV virus in the blood (viral load) to increase. Ritonavir-boosted HIV protease inhibitors include ritonavir-boosted Reyataz (atazanavir), ritonavir-boosted Prezista (darunavir), and Kaletra (lopinavir/ritonavir).

“Patients should not stop taking any of their hepatitis C or HIV medicines without talking to their healthcare professional.  Patients should contact their healthcare professional with any questions or concerns.

“Healthcare professionals who started patients infected with both chronic HCV and HIV on Victrelis while the patient was taking antiretroviral therapy containing one of these ritonavir-boosted protease inhibitors should closely monitor patients for treatment response (no HCV virus detected in the blood) and for potential HCV or HIV virologic rebound (HCV or HIV virus is detected in the blood again after becoming undetectable). …

“In light of both the findings of the drug-drug interaction study and the clinical trial, FDA has revised the Victrelis drug label to state that co-administration of Victrelis with ritonavir-boosted Reyataz (atazanavir), ritonavir-boosted Prezista (darunavir), or Kaletra (lopinavir/ritonavir) to patients infected with both chronic HCV and HIV is not recommended at this time.”

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Study Suggests Osteoporotic Fracture Risk Is Associated with Cumulative Exposure to Tenofovir and Other Antiretrovirals

“Whereas tenofovir (TDF) exposure has been associated with decreased bone density, it remains unclear whether it is associated with increased risk of osteoporotic fractures. …

“Patients with any osteoporotic fracture (defined as wrist, vertebral or hip fracture) occurring after HIV diagnosis were identified by International Classification of Diseases - 9th Revision (ICD-9) code in the Veterans Affairs' Clinical Case Registry from 1988 to 2009. Osteoporotic fracture risk associated with cumulative exposure to TDF and other antiretrovirals was examined in univariate analysis and multivariate model 1 (MV1 - controlling for race, age, tobacco use, diabetes, body mass index, and hepatitis C status) and model 2 (MV2 - controlling for MV1 variables + concomitant antiretroviral exposures). …

“Among 56660 patients evaluated, TDF exposure (total 46062 person-years) was associated with an osteoporotic fracture hazard ratio of 1.080 [95% confidence interval (CI) 1.02-1.15, P<0.001] in univariate analysis, 1.06 (0.99-1.12) in MV1 and 1.06 (0.99-1.14) in MV2. Among patients entering the cohort in the highly active antiretroviral therapy (HAART) era (n=32439), TDF exposure was associated with a yearly hazard ratio for osteoporotic fracture of 1.16 (95% CI 1.08-1.24, P < 0.001) in univariate model, 1.13 (1.05-1.21, P=0.001) in MV1 and 1.12 (1.03-1.21, P=0.011) in MV2. Boosted protease inhibitor exposure was associated with hazard ratio of 1.11 (1.05-1.18, P=0.001) in univariate model, 1.08 (1.01-1.15, P=0.026) in MV1 and 1.05 (0.97-1.13, P=0.237) in MV2. Among protease inhibitors, lopinavir/ritonavir (LPV/RTV) had an osteoporotic fracture hazard ratio of 1.09 (CI 1.00-1.20, P=0.051) in MV2. …

“Cumulative exposure to TDF and, among protease inhibitors, LPV/RTV was independently predictive of increased risk of osteoporotic fracture in the HAART era.”

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