[india-drug] Re: Metallic taste with nitroimidazoles (3)

["Medicine Information Centre @ NIPER" <medinfo@niper.ac.in>]

Re: Metallic taste with nitroimidazoles (3)
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4.07.06

Dear Dr. Aggarwal,

Further to your query on nitroimidazoles, I am pleased to provide the required information. 

The metallic taste of metronidazole and ornidazole is attributed to nitro moiety present in both these drugs. Though the nitroimidazole moiety is same in both of them but there is difference in their parent chain.

Metronidazole is 2-(2-methyl-5-nitro-imidazol-1-yl) ethanol and ornidazole is 1-chloro-3-(2-methyl-5-nitroso-imidazol-1-yl) propan-2-ol. 

In view of the chemical structures of the two drugs, the only reason for smaller extent of metallic taste of ornidazole can be difference in the doses.  It seems that ornidazole is used in smaller doses and hence has less metallic taste in comparison to metronidazole. 
(In case of amoebiasis, metronidazole 400 to 800 mg TID, ornidazole 500mg TID and in amoebic dysentery, metronidazole 1.5-2.5 g OD, ornidazole 1.5 g OD)

Finally, as mentioned in Micromedex  2005, the metallic taste in the mouth and gastrointestinal complaints occur frequently particularly at higher doses.
So, the smaller dose of ornidazole seems to be the most likely reason for the lesser metallic taste as compared to metronidazole.

I hope you find the information useful. Please do not hesitate to write back.

Thanks, 

Ms. Sukhpreet
Medicine Information Centre
NIPER, S A S NAGAR (PUNJAB), INDIA
http://www.niper.gov.in/medicine.htm
Contact us via email at medinfo@niper.ac.in

P.S.  The structures of metronidazole and ornidazole can not be given because of the limitation of the e-group.

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