Effects of metronidazole, tinidazole, captopril and valsartan on taste and serum levels of zinc and magnesium

OBJECTIVE: To study the effect of metronidazole, tinidazole, captopril and valsartan on the levels of zinc and magnesium in the serum of rabbits and humans and the histology of taste buds in rabbits.

METHODS: We conducted this study in the College of Medicine and Teaching Hospital, Basrah, Iraq from April 2005 to September 2006. It was in 2 parts: a clinical observational study of 54 patients treated with one of these drugs. The second part involved oral administration of metronidazole (45mg/kg), tinidazole (40mg/kg), captopril (3mg/kg) or valsartan (3mg/kg) or normal saline to 42 rabbits randomly. Serum zinc and magnesium were measured, and histological sections of tongues were examined for taste buds.

RESULTS: In rabbits, oral metronidazole (13.6%) or tinidazole (7%) resulted in a significant reduction in serum zinc. Reductions in captopril (6.7%) and valsartan (4.2%) were smaller and insignificant. Body weight increased by 15.5gm (1391±225.3 gm to 1407±223.2 gm) in the control group, a lesser increase of approximately 8 gm, was found in the metronidazole group (1452±222.6 gm to 1460±221.9 gm). Rabbit tongues showed moderate degeneration of taste buds caused by tinidazole, severe degeneration of captopril and minimal changes of valsartan. In humans, the drugs did not result in significant changes in serum zinc or magnesium. Approximately 73.3% of patients in the metronidazole group and 11.1% in the valsartan group had taste changes.

CONCLUSION: It is concluded that metronidazole and tinidazole, but not captopril or valsartan resulted in a significant reduction of zinc level in rabbit, but not in human. Captopril and not valsartan caused severe degeneration in taste buds. Serum zinc level seems not to be related to taste buds changes.