Secnidazole (Monograph)

Brand name: Solosec
Drug class: Antiprotozoals, Nitroimidazole-derivative

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

Introduction

Antiprotozoal¹¹ and antibacterial;^{1 11} nitroimidazole derivative.^{1 4 5}

Uses for Secnidazole

Bacterial Vaginosis

Treatment of bacterial vaginosis.^{1 3}

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.^{344 345}

Treatment recommended in symptomatic women to relieve signs and symptoms of infection;^{344 345} routine treatment of male sexual partner(s) not usually recommended.^{344 345} Relapse or recurrence is common, regardless of treatment regimen used.^{344 345}

Secnidazole Dosage and Administration

Administration

Oral Administration

Administer orally without regard to meals.¹

Commercially available as single-dose packets containing 2 g of secnidazole as oral granules.¹

Take oral granules by sprinkling contents of single-dose packet onto applesauce, yogurt, or pudding;¹ granules will not dissolve and are not intended to be administered in any liquid.¹ Consume entire contents of the mixture within 30 minutes (without chewing or crunching the granules).¹ May drink a glass of water after administration to aid in swallowing.¹

Dosage

Adults

Bacterial Vaginosis

Oral

2 g as a single dose.¹

Special Populations

Manufacturer makes no specific dosage recommendations for patients with hepatic or renal impairment or for geriatric patients.¹

Cautions for Secnidazole

Contraindications

• Known hypersensitivity to secnidazole, other ingredients in the formulation, or other nitroimidazole derivatives.¹

Warnings/Precautions

Vulvovaginal Candidiasis

Use of secnidazole may result in vulvovaginal candidiasis.¹ Symptomatic vulvovaginal candidiasis may require treatment with an antifungal.¹

Carcinogenicity

Carcinogenicity observed in mice and rats treated chronically with nitroimidazole derivatives structurally related to secnidazole (e.g., metronidazole).^{1 10} In some rodent studies, lifetime exposure to nitroimidazoles was associated with tumors affecting liver, lung, mammary, and lymphatic tissues.¹

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.¹ Manufacturer states avoid chronic use of secnidazole.¹

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.¹

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.¹

When selecting or modifying anti-infective therapy, use results of culture and in vitro susceptibility testing.¹ In the absence of such data, consider local epidemiology and susceptibility patterns when selecting anti-infectives for empiric therapy.¹

Specific Populations

Pregnancy

Insufficient data on use during pregnancy.¹ 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.¹

Lactation

Not known if distributed into human milk, affects breast-fed infant, or affects milk production.¹ Other nitroimidazole derivatives are distributed into human milk.¹

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.¹ 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.¹

Pediatric Use

Safety and efficacy not established in pediatric patients <18 years of age.¹

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.¹

Hepatic Impairment

Not studied in patients with hepatic impairment.²

Renal Impairment

Not studied in patients with renal impairment.²

Common Adverse Effects

Vulvovaginal candidiasis,^{1 3} headache,^{1 3} GI effects (nausea,^{1 3} vomiting,¹ diarrhea,^{1 3} dysgeusia,¹ abdominal pain)^{1 3} , vulvovaginal pruritus.^{1 3}

Drug Interactions

Drugs Affecting or Metabolized by Hepatic Microsomal Enzymes

Minimally metabolized by CYP isoenzymes;² unlikely to be affected by CYP inducers or inhibitors.²

Specific Drugs

Secnidazole Pharmacokinetics

Absorption

Food

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.¹

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/mL¹ and median time to peak plasma concentrations is 4 hours.^{1 8} 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.¹

Peak plasma concentrations and AUC when secnidazole admixed in applesauce similar to those observed when admixed in pudding or yogurt.^{1 8}

Distribution

Plasma Protein Binding

<5% bound to plasma proteins.¹

Elimination

Metabolism

In vitro, ≤1% metabolized by CYP isoenzymes.¹

Elimination Route

Approximately 15% of single 2-g oral dose is excreted unchanged in urine.¹

Half-life

Approximately 17 hours.^{1 8}

Stability

Storage

Oral

Granules

20–25°C (may be exposed to 15–30°C).¹

Actions and Spectrum

• 5-Nitroimidazole antiprotozoal¹¹ and antibacterial.^{1 4 5 11}

• Exact mechanism of action not fully elucidated.⁴

• Secnidazole is a prodrug that is activated after entry into bacterial cells where the nitro group is reduced by bacterial enzymes to form short-lived radical anions.^{1 4} Radical anions believed to interfere with DNA synthesis of susceptible bacteria.¹

• Anaerobes: Active against Bacteroides,^{1 4 5} Gardnerella vaginalis,¹ Prevotella,^{1 5} Mobiluncus,¹ and Megasphaera-like type I/II.^{1 5}

• G. vaginalis^{5 6} and Mobiluncus⁵ with reduced in vitro susceptibility or resistance to secnidazole reported.^{5 6} Some bacteria with reduced in vitro susceptibility to metronidazole also have reduced susceptibility to secnidazole;¹ clinical importance of this possible cross-resistance not known.¹

• Protozoa: Active against Giardia duodenalis (also known as G. lamblia or G. intestinalis),^{11 12} Trichomonas vaginalis,^{11 13} and Entamoeba histolytica.¹¹

Advice to Patients

• Advise patients to read the patient information provided by the manufacturer.¹

• Advise patients that antibacterials (including secnidazole) should only be used to treat bacterial infections and not used to treat viral infections (e.g., the common cold).¹

• Instruct patients to sprinkle entire contents of single-dose packet of secnidazole granules on applesauce, yogurt, or pudding and consume entire mixture within 30 minutes (without chewing or crunching the granules).¹ Inform patients that the granules are not intended to be dissolved in any liquid.¹

• Advise patients that secnidazole may be taken without regard to meals.¹

• Advise patients that use of secnidazole may result in vulvovaginal candidiasis that may require treatment with an antifungal.¹

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs and herbal supplements, as well as any concomitant illnesses.¹

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.¹ Advise women not to breast-feed during and for 96 hours following administration of secnidazole.¹

• Importance of informing patients of other important precautionary information.¹ (See Cautions.)

Preparations

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.

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