Tetany: possible adverse effect of bevacizumab.

Background: Bevacizumab a recombinant humanized monoclonal antibody was approved in 2004 by US FDA for metastatic colorectal cancer. It is reported to cause potentially serious toxicities including severe hypertension, proteinuria, and congestive heart failure.

Aim: To correlate adverse event tetany with the use of bevacizumab.

Materials And Methods: World Health Organization's Uppsala Monitoring Centre, Sweden, for reporting of adverse drug reactions from all over the world, identified 7 cases with tetany-related symptoms to bevacizumab from four different countries. These 7 patients reported to UMC database developed adverse events described as musculoskeletal stiffness (1), muscle spasm (1), muscle cramps (1), lock jaw or jaw stiffness (4), and hypertonia (1), with hypocalcaemia.

Results: After detailed study of the possible mechanism of actions of bevacizumab and factors causing tetany, it is proposed that there is a possibility of tetany by bevacizumab, which may occur by interfering with calcium metabolism. Resorption of bone through osteoclasts by affecting VEGF may interfere with calcium metabolism. Another possibility of tetany may be due to associated hypomagnesaemia, hypokalemia, or hyponatremia.

Conclusions: Tetany should be considered as a one of the signs. Patient on bevacizumab should carefully watch for tetany-related symptoms and calcium and magnesium levels for their safety.