Protease Inhibitors Can Impair Muscle Repair

HIV protease inhibitors have been suspected to play a role in muscle wasting, and now Canadian researchers may have discovered why. Scientists from the Lady Davis Institute for Medical Research in Montreal studied the effects of the protease inhibitors Crixivan and Norvir on muscle cells, and discovered that the drugs impair the formation of muscle cells known as myotubes by interfering with calpain enzymes that play a role in muscle development. Muscle cells exposed to the protease inhibitors exhibited reduced calpain activity, and the cells failed to developed multinucleated myotubes. 'Our in vitro data suggest that the protease inhibitors present in [antiretroviral therapy] might contribute to the muscle wasting by reducing muscle repair and remodeling,' the researchers conclude. The full study appears in the October issue of AIDS Research and Human Retroviruses.