<prompt> The following anti-HIV drug should not be combined with zidovudine because of mutual antagonismNevirapineRitonavirStavudineLamivudine  <response>: Stavudine d4T It is also a thymidine analogue which acts by utilizing the thymidine kinase for activation, AZTzidovudine antagonises the effect of stavudine and the two should not be used together. It should also not be combined with didanosine, because both cause peripheral neuropathy. side effects:- Frequent peripheral neuropathy, lipodystrophy, lactic acidosis, and rarely pancreatitis are noted. Ref:- kd tripathi; pg num:-807 