Trichomoniasis Medication

Updated: Jan 02, 2020
  • Author: Darvin Scott Smith, MD, MSc, DTM&H; Chief Editor: Michael Stuart Bronze, MD  more...
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Medication

Medication Summary

The following treatment options are recommended by the CDC:

  • Single-dose 2-g oral metronidazole therapy
  • Prolonged metronidazole therapy with 500 mg twice daily for 7 days
  • Single-dose 2-g oral tinidazole therapy

Single-dose tinidazole or metronidazole appears to be equally effective in the treatment of trichomoniasis. Tinidazole is generally more expensive than metronidazole but may have fewer side-effects and remains in serum longer. Single-dose therapy with metronidazole or tinidazole improves patient compliance and results in a lower total dose than the week-long metronidazole schedule, although the week-long schedule may be useful in some situations, such as in patients with HIV infection or those who are breastfeeding. [11] Topical treatments are not recommended due to inadequate therapeutic levels. [11] Treatment with oral metronidazole has not been shown to have teratogenic effects [122, 123] and may prevent transmission to the infant. The CDC does not offer a definitive recommendation on treating pregnant patients with symptomatic trichomoniasis but currently recommends that a single 2-g dose of metronidazole be used when treatment is prescribed. [11] Infected asymptomatic pregnant women may wish to defer treatment to after 37 weeks’ gestation. [48] Tinidazole is a pregnancy Class C agent and should not be used by pregnant women.

Drug-resistance in T vaginalis infection is rare, despite the prevalent use of nitroimidazole drugs. Treatment failures may require a higher-dose regimen, a longer course of the agent, or the use of different nitroimidazoles. In cases of resistance, nimorazole, ornidazole, furazolidone, ornidazole, and hamycin have been used with success. [117]

Consultation with CDC experts may be advisable for patients in whom treatment fails and in whom reinfection is ruled out (770-488-4115). Consultation with an infectious diseases specialist, a gynecologist, or both may be helpful.

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Antiprotozoal agents

Class Summary

Antiprotozoal therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting. In the treatment of trichomoniasis, 5-nitroimidazole drugs are the only widely used antiprotozoal agents. [11] 5-Nitroimidazoles are believed to disrupt the helical structure of DNA in trichomonads, ultimately leading to cell death. [115] The exact mechanisms of many antiprotozoal agents, including 5-nitroimidazoles, are not well understood.

Metronidazole (Flagyl)

Metronidazole is highly effective in the treatment of many anaerobic bacterial and protozoal infections. Oral metronidazole is the drug of choice for trichomoniasis. Single-dose therapy with 2 g orally is as effective as prolonged therapy with 500 mg twice daily for 7 days. Single-dose therapy increases compliance. Cure rates of 90-95% for trichomoniasis have been reported with these recommended dosages. Treating the patient's sexual partners further improves the cure rate. Trichomonal resistance to this agent has also been reported; current resistance rates are reported at 5-10%.

If treatment with either single-dose or multidose therapy fails, a regimen of 2 g of oral metronidazole or tinidazole for 5 days may be considered. Metronidazole gel is not recommended for the treatment of trichomoniasis because therapeutic levels are not reached.

Patients should not consume alcohol during the course of treatment and for 24 hours after the last dose. The CDC currently recommends that infected symptomatic pregnant females be treated with 2 g metronidazole in a single dose. Infected asymptomatic pregnant women may wish to defer treatment to after 37 weeks' gestation.

The mode of action of metronidazole is not well understood. The drug appears to be absorbed into cells; intermediate metabolites bind DNA and inhibit protein synthesis, causing cell death.

Tinidazole (Tindamax)

Tinidazole has a longer half-life (12-14 h) than metronidazole (6-7 h). Therapy consists of a single oral 2-g dose taken with food. Reported cure rates for trichomoniasis range from 86-100%. Randomized clinical trials comparing single 2-g doses have shown metronidazole and tinidazole to be equally effective. The CDC has reported cases of metronidazole-resistant T vaginalis that was susceptible to tinidazole.

Patients on tinidazole therapy should not consume alcohol during therapy or for 72 hours after completion of the medication. Tinidazole is not recommended for the treatment of trichomoniasis in pregnant women.

Tinidazole is a 5-nitroimidazole derivative used for susceptible protozoal infections. The nitro group is reduced by a cell extract of Trichomonas. The free nitro radical generated is thought to be responsible for antiprotozoal activity against T vaginalis. The advantage of tinidazole over metronidazole is that it has fewer adverse effects, including nausea and vomiting, and may be better tolerated in a single high dose.

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