Short-term therapy for mixed vaginal infections

Secnidazole for Trichomoniasis in Women and Men

INTRODUCTION

Secnidazole (SEC), newly FDA-approved for trichomoniasis, is a potent 5-nitroimidazole with selective toxicity against various infections. It has been used internationally to treat trichomoniasis, bacterial vaginosis, and other infections for decades. Trichomoniasis is the most common non-viral sexually transmitted infection worldwide and is associated with significant morbidity. In comparison to the only other approved treatments for trichomoniasis in the U.S.-metronidazole and tinidazole-SEC has favorable pharmacokinetics, including a longer half-life, and a lower minimal lethal concentration against Trichomonas vaginalis.

OBJECTIVES

Provide an updated, comprehensive review of the literature evaluating SEC as a treatment for trichomoniasis in women and men.

METHODS

We conducted a search to identify existing research on SEC and trichomoniasis. On August 6, 2021, we searched MEDLINE using the terms "secnidazole" and "trichomon.*" We excluded reviews, editorials, case reports, and small case series.

RESULTS

We identified 29 articles; 14 of which were included: 5 reported in vitro pharmacologic data on SEC, 6 were observational studies, and 4 were controlled clinical trials (1 observational study also reported in vitro pharmacologic data). Six studies reported data on women only, 1 on men only, and 3 on women and men. These studies showed that SEC-as a single dose or 3-day course-had comparable efficacy to multi-dose metronidazole for treating trichomoniasis in women and men, was generally well tolerated by patients, and had a favorable pharmacokinetic profile. A single 2-g dose of SEC also led to a microbiologic cure rate of 92.2% in the first randomized, double-blind, placebo-controlled study of trichomonas-infected US-based women.

CONCLUSION

SEC is an efficacious and safe treatment for women and men with trichomoniasis. Single-dose administration makes it a favorable treatment option for patients, especially in cases where adherence to other multi-dose treatment regimens could be problematic. Christina A. Muzny and Olivia T. Van Gerwen. Secnidazole for Trichomoniasis in Women and Men. Sex Med Rev 2022;10:255-262.

Secnidazole: next-generation antimicrobial agent for bacterial vaginosis treatment

Secnidazole is a next-generation 5-nitroimidazole approved for more than three decades in Europe, Asia, South America and Africa and recently in the USA as a single-dose (2 g) treatment of bacterial vaginosis (BV). Secnidazole is characterized by potent in vitro antimicrobial activity against BV-associated pathogens, as well as prolonged terminal elimination half-life and systemic exposure. These characteristics form the basis of effective and safe treatment of BV with a 2-g single-dose secnidazole regimen, which was recently confirmed in double-blind, placebo-controlled clinical trials conducted in the USA. The option to treat BV with single-dose secnidazole not only cures the primary infection but also may diminish risks of serious sequelae of untreated or undertreated infection.

Tinidazole for bacterial vaginosis

Tinidazole has been used for bacterial vaginosis (BV) outside the USA for almost four decades. Tinidazole has recently been resurrected and FDA approved for trichomoniasis and BV in the USA and is being restudied as an alternative to metronidazole for BV. In vitro antimicrobial activity and pharmacokinetics studies indicate that when compared directly with metronidazole, tinidazole has minor but possibly relevant antimicrobial as well as pharmacokinetic advantages. Clinical comparisons have been infrequent, although the limited head-to-head studies indicate minimal therapeutic advantage with tinidazole. Perhaps the more relevant differences relate to the enhanced tolerance and reduced toxicity of tinidazole. Currently, studies are still ongoing directly comparing the clinical efficacy of metronidazole and tinidazole. These studies should establish the role of tinidazole in the treatment of BV; however, cure rates are unlikely to be significantly different.

Bacterial vaginosis: an update on diagnosis and treatment

Bacterial vaginosis is the most common cause of vaginal complaints. Bacterial vaginosis is further associated with a sizeable burden of infectious complications. Diagnosis relies on standardized clinical criteria or on scoring bacterial cell morphotypes on a Gram-stained vaginal smear. A few point-of-care tests have not gained footage in clinical practice, but molecular diagnosis is now pending. Treatment remains cumbersome and clinicians are currently rather poorly armed to treat bacterial vaginosis in the long run. As an adjuvant to standard treatment with antibiotics, alternative treatments with antiseptics and disinfectants, vaginal-acidifying and -buffering agents, and probiotics hold some promise for long-term prevention.

Effectiveness of Two Tinidazole Regimens in Treatment of Bacterial Vaginosis

OBJECTIVE

To assess the effectiveness at 21-30 days after treatment of tinidazole administered orally at 1 g once daily for 5 days and 2 g once daily for 2 days, compared with placebo, in the treatment of bacterial vaginosis, using rigorous U.S. Food and Drug Administration (FDA)-recommended criteria to define cure.

METHODS

A total of 235 women at 10 U.S. centers participated in this prospective, randomized, double-blinded, placebo-controlled trial. Presence or absence of all five following criteria was required to define diagnosis or cure of bacterial vaginosis: 1) clue cells were at least 20% of squamous cells in microscopic examination of vaginal fluid; 2) positive potassium hydroxide whiff test; 3) a homogeneous, thin, white-gray vaginal discharge; 4) vaginal pH greater than 4.5; and 5) Nugent score greater than or equal to 4 on Gram-stained vaginal fluid. Compliance, tolerability, and safety were assessed using patient diaries and interviews at 8-10 days and 21-30 days after treatment. Cochran-Mantel-Haenszel statistical analysis with Bonferroni adjustment was used to compare outcomes.

RESULTS

Superior efficacy was demonstrated by tinidazole for the 1 g once daily for 5 days regimen (36.8% cured, P<.001, number needed to treat 3.2) and for the 2 g once daily for 2 days regimen (27.4% cured, P<.001, number needed to treat 4.5), when compared with placebo (5.1% cured) in the primary endpoint analysis. Using more traditional criteria for cure, efficacy was greater. Compliance with study therapy and tolerability were comparable in the three treatment groups.

CONCLUSION

Both tinidazole regimens studied provided effective treatment for bacterial vaginosis.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00229216

LEVEL OF EVIDENCE

I.

Tinidazole for the treatment of vaginal infections

Tinidazole has been used for vaginal infection worldwide but not in the US for > 40 years. Recently, tinidazole has been re-introduced and approved by the FDA for trichomoniasis and restudied as an alternative to metronidazole for bacterial vaginosis. In vitro antimicrobial activity and pharmacokinetics studies indicate that tinidazole has minor but possibly relevant antimicrobial as well as pharmacokinetic advantages when compared directly with metronidazole. Clinical comparison has been infrequent although the limited head-to-head studies indicate minimal therapeutic advantage with tinidazole. Perhaps the more relevant differences relate to the enhanced tolerance and reduced toxicity of tinidazole. Ongoing, as yet incomplete, studies directly comparing the clinical efficacy of metronidazole and tinidazole for bacterial vaginosis should clarify the status of tinidazole; however, cure rates are unlikely to be significantly different. Although uncommon, high-level trichomonal metronidazole resistance can be reliably cured by using tinidazole, which is an invaluable advantage.

Determination of secnidazole in human plasma by high-performance liquid chromatography with UV detection and its application to the bioequivalence studies

A simple, accurate, precise and sensitive HPLC-UV method was developed for the determination of secnidazole in human plasma. Secnidazole and tinidazole (IS) were extracted from 0.2 mL of human plasma by ethyl acetate. Secnidazole was then separated by HPLC on a Diamond C(18) column and quantified by ultraviolet detection at 319 nm. The mobile phase consisted of acetonitrile-aqueous 5 mm sodium acetate (30:70, v/v) containing of 0.1% acetic acid adjusted to pH 4.0, and the flow rate was 1.0 mL/min. The low limit of quantification was 0.1 microg/mL. The method was linear over the concentration range 0.1-25.0 microg/mL (R(2) = 1.000). The recovery of secnidazole from human plasma ranged from 76.5 to 89.1%. Inter- and intra-assay precision ranged from 3.3 to 10.7%. Secnidazole in plasma was stable when stored at ambient temperature for 8 h, at -20 degrees C for 2 weeks and at -20 degrees C for three freeze-thaw cycles. The developed method was successfully applied to the pharmacokinetic and bioequivalence studies between test and reference secnidazole tablets following a single 500 mg oral dosage to 20 healthy volunteers of both genders. Pharmacokinetics parameters T(max), C(max), AUC(0-)t, AUC(0-infinity), T(1/2) were determined of both preparations. The analysis of variance (ANOVA) did not show any significant difference between the two preparations and 90% confidence intervals fell within the acceptable range for bioequivalence. It was concluded that the two secnidazole preparations are bioequivalence and may be used interchangeably.