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Secnidazole (Monograph)

Brand name: Solosec
Drug class:

Medically reviewed by on Apr 10, 2024. Written by ASHP.


Antiprotozoal and antibacterial; nitroimidazole derivative.

Uses for Secnidazole

Bacterial Vaginosis

Treatment of bacterial vaginosis.

Bacterial vaginosis is a polymicrobial syndrome that can occur when normal vaginal hydrogen peroxide-producing Lactobacillus are replaced by overgrowth of various anaerobic bacteria (e.g., Atopobium vaginae, Bacteroides, Mobiluncus, Prevotella), Gardnerella vaginalis, Ureaplasma urealyticum, Mycoplasma hominis, or other bacteria.

Treatment recommended in symptomatic women to relieve signs and symptoms of infection; routine treatment of male sexual partner(s) not usually recommended. Relapse or recurrence is common, regardless of treatment regimen used.

Secnidazole Dosage and Administration


Oral Administration

Administer orally without regard to meals.

Commercially available as single-dose packets containing 2 g of secnidazole as oral granules.

Take oral granules by sprinkling contents of single-dose packet onto applesauce, yogurt, or pudding; granules will not dissolve and are not intended to be administered in any liquid. Consume entire contents of the mixture within 30 minutes (without chewing or crunching the granules). May drink a glass of water after administration to aid in swallowing.



Bacterial Vaginosis

2 g as a single dose.

Special Populations

Manufacturer makes no specific dosage recommendations for patients with hepatic or renal impairment or for geriatric patients.

Cautions for Secnidazole



Vulvovaginal Candidiasis

Use of secnidazole may result in vulvovaginal candidiasis. Symptomatic vulvovaginal candidiasis may require treatment with an antifungal.


Carcinogenicity observed in mice and rats treated chronically with nitroimidazole derivatives structurally related to secnidazole (e.g., metronidazole). In some rodent studies, lifetime exposure to nitroimidazoles was associated with tumors affecting liver, lung, mammary, and lymphatic tissues.

Not known if positive tumor findings in rodent studies using other nitroimidazoles indicate a risk to patients receiving a single dose of secnidazole to treat bacterial vaginosis. Manufacturer states avoid chronic use of secnidazole.

Selection and Use of Anti-infectives

To reduce development of drug-resistant bacteria and maintain effectiveness of secnidazole and other anti-infectives, use only for treatment of infections proven or strongly suspected to be caused by susceptible bacteria.

Prescribing secnidazole in the absence of proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases risk of development of drug-resistant bacteria.

When selecting or modifying anti-infective therapy, use results of culture and in vitro susceptibility testing. In the absence of such data, consider local epidemiology and susceptibility patterns when selecting anti-infectives for empiric therapy.

Specific Populations


Insufficient data on use during pregnancy. In animal reproduction studies, no evidence of adverse developmental outcomes when oral secnidazole used in pregnant rats and rabbits during organogenesis at exposures up to fourfold greater than recommended human dose.


Not known if distributed into human milk, affects breast-fed infant, or affects milk production. Other nitroimidazole derivatives are distributed into human milk.

Due to the potential for serious adverse effects, including tumorigenicity, breast-feeding not recommended during secnidazole treatment and for 96 hours after administration of the drug. In this situation, nursing mother may choose to pump and discard her breast milk during and for 96 hours after secnidazole treatment and feed infant with stored human milk or formula during this period.

Pediatric Use

Safety and efficacy not established in pediatric patients <18 years of age.

Geriatric Use

Clinical studies did not include a sufficient number of patients ≥65 years of age to determine if they respond differently than younger adults.

Hepatic Impairment

Not studied in patients with hepatic impairment.

Renal Impairment

Not studied in patients with renal impairment.

Common Adverse Effects

Vulvovaginal candidiasis, headache, GI effects (nausea, vomiting, diarrhea, dysgeusia, abdominal pain) , vulvovaginal pruritus.

Drug Interactions

Drugs Affecting or Metabolized by Hepatic Microsomal Enzymes

Minimally metabolized by CYP isoenzymes; unlikely to be affected by CYP inducers or inhibitors.

Specific Drugs




Estrogens and progestins

Oral contraceptive containing ethinyl estradiol and norethindrone: Concomitant use with secnidazole does not result in clinically important changes in ethinyl estradiol or norethindrone exposures

Oral contraceptive containing ethinyl estradiol and norethindrone: Secnidazole may be used concomitantly


No effect on aldehyde dehydrogenase activity at clinically important doses

Secnidazole Pharmacokinetics



Administration of single 2-g dose of secnidazole (as granules admixed with applesauce) followed by a high-fat meal does not affect peak plasma concentrations or AUC of the drug compared with administration in fasting state.

Plasma Concentrations

Following oral administration of single 2-g dose (as granules admixed with applesauce) in healthy, fasting adult females, mean peak plasma concentrations of the drug are 45.4 mcg/mL and median time to peak plasma concentrations is 4 hours. Mean plasma concentrations are 22.1, 9.2, 3.8, and 1.4 mcg/mL at 24, 48, 72, and 96 hours, respectively, after the dose.

Peak plasma concentrations and AUC when secnidazole admixed in applesauce similar to those observed when admixed in pudding or yogurt.


Plasma Protein Binding

<5% bound to plasma proteins.



In vitro, ≤1% metabolized by CYP isoenzymes.

Elimination Route

Approximately 15% of single 2-g oral dose is excreted unchanged in urine.


Approximately 17 hours.





20–25°C (may be exposed to 15–30°C).

Actions and Spectrum

Advice to Patients


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.



Dosage Forms


Brand Names




2 g



AHFS DI Essentials™. © Copyright 2024, Selected Revisions April 10, 2024. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

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