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Although, metronidazole, tinidazole, ornidazole, secnidazole, are all nitroimidazole drugs, for the amoeba, giardia, trichomoniasis and other protozoa, Gram-positive bacteria, Gram-negative Anaerobic bacteria have a powerful effect, but there are certain differences between the four drugs.

1. Secnidazole: approved only for antigenic insects

Secnidazole has the longest elimination half-life of about 17 to 29 hours. The half-lives of metronidazole, tinidazole and ornidazole are: 7~8 hours, 12~13 hours, 12~14 hours.

Secnidazole, together with metronidazole, tinidazole, and ornidazole, are 5-nitroimidazole derivatives, all of which have certain antigenic and anti-anaerobic activity.

However, the anti-anaerobic activity of secnidazole is slightly better than metronidazole and is not superior to tinidazole and ornidazole. It is currently only approved for trichomoniasis, amebiasis, and giardiasis.

2. Ornidazole: does not cause a disulfiram-like reaction

In vitro studies showed that ornidazole and ornidazole were similar or slightly stronger than the anti-anaerobic activity of metronidazole. The incidence of adverse reactions: left ornidazole < ornidazole < metronidazole.

One of the most important features of ornidazole is that it does not interfere with the metabolism of acetaldehyde and does not cause a disulfiram-like reaction.

Metronidazole: during and 2 weeks after drug withdrawal; tinidazole: during and after 3 days of withdrawal; secnidazole: alcoholic beverages or foods are prohibited during and after the drug withdrawal.

3. Pregnant male: careful use of tinidazole, ornidazole

5-nitroimidazole antibiotics, long-term high-dose applications have carcinogenic effects on rodents, but there is no evidence of a significant increase in the risk of cancer in humans.

Although animal experiments have not seen teratogenic effects of 5-nitroimidazole antibacterial drugs, they can pass through the placental barrier; they can be secreted into milk, and the concentration in milk is equivalent to the plasma concentration.

It is worth reminding that tinidazole and ornidazole have reversible inhibition on the reproductive function of male rats, and men who are pregnant should be used cautiously.

4. Tinidazole: antibacterial activity is 2 to 4 times that of metronidazole

The anti-anaerobic activity and anti-protozoal activity of tinidazole is better than that of metronidazole, which is about 2 to 4 times that of metronidazole, and the adverse reaction is also significantly lower than that of metronidazole.

5. Special attention: metronidazole can cause encephalopathy

The most common adverse reactions of nitroimidazole pituitary drugs are headache, nausea, metallic taste, dry mouth, glossitis, stomatitis, etc., usually do not affect treatment.

Metronidazole can penetrate the blood-brain barrier and cause neurotoxic reactions. Metronidazole encephalopathy can occur in any age group of male and female adults, mainly manifested as cerebellar dysfunction, altered mental status or seizures.

Metronidazole encephalopathy is associated with long-term, high cumulative doses of metronidazole treatment, usually occurring several weeks after administration.

Inform patients:

1 When exercise disorders, ataxia, convulsions and encephalopathy occur, the drug must be discontinued;

2 Should be discontinued when numbness or paresthesia occurs in the limbs (can cause severe sensory neuropathy).

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