Tinidazole vs. Metronidazole

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Nitroimidazoles: Tinidazole and Metronidazole

Side-by-side diagrams of tinidazole and metronidazole molecules show they have identical imidazole rings and nitro groups, but they differ in their substituents.

Figure 1

Metronidazole and tinidazole belong to a class of drugs called the nitroimidazoles. (Metronidazole is a first generation nitroimidazole and tinidazole is a second generation nitroimidazole.)

Nitroimidazoles are organic compounds that are effective against many parasitic infections, including trichomoniasis, giardiasis, and intestinal amebiasis. They are also used to fight certain infections caused by rod-shaped, Gram negative, anaerobic bacteria.

Nitroimidazoles are characterized by a five-sided imidazole ring with an attached nitro group. The biologic activity of the nitroimidazoles results from the reduction of their nitro groups, which occurs best in an anaerobic environment.1

Changing the substituents on the imidazole ring may render one compound more therapeutically desirable than another.2 While tinidazole and oral metronidazole are similarly effective in the treatment of (non-metronidazole-resistant) trichomoniasis, tinidazole offers a number of advantages over metronidazole:3-7

  • Tinidazole has a better pharmacokinetic and pharmacodynamic profile.
  • Tinidazole has a better safety and tolerability spectrum.
  • Tinidazole has a preserved activity against some metronidazole-resistant bacteria.
  1. Müller M. Reductive activation of nitroimidazoles in anaerobic microorganisms. Biochem Pharmacol. 1986 Jan 1;35(1):37-41.
  2. Goldman P. The development of 5-nitroimidazoles for the treatment and prophylaxis of anaerobic bacterial infections. J Antimicrob Chemother. 1982 Aug;10 Suppl A:23-33.
  3. Manes G, Balzano A. Tinidazole: from protozoa to Helicobacter pylori--the past, present and future of a nitroimidazole with peculiarities. Expert Rev Anti Infect Ther. 2004 Oct;2(5):695-705.
  4. Crowell AL, Sanders-Lewis KA, Secor WE. In vitro metronidazole and tinidazole activities against metronidazole-resistant strains of Trichomonas vaginalis. Antimicrob Agents Chemother. 2003 Apr;47(4):1407-9.
  5. Sobel JD, Nyirjesy P, Brown W. Tinidazole therapy for metronidazole-resistant vaginal trichomoniasis. Clin Infect Dis. 2001 Oct 15;33(8):1341-6. Epub 2001 Sep 17.
  6. Mammen-Tobin A, Wilson JD. Management of metronidazole-resistant Trichomonas vaginalis--a new approach. Int J STD AIDS. 2005 Jul;16(7):488-90.
  7. Nanda N, Michel RG, Kurdgelashvili G, Wendel KA. Trichomoniasis and its treatment. Expert Rev Anti Infect Ther. 2006 Feb;4(1):125-35.