Metronidazole Vaginal

Metronidazole vaginal gel is indicated for the treatment of bacterial vaginosis in females 12 years of age and older. Metronidazole vaginal gel is a nitroimidazole antimicrobial indicated for the treatment of bacterial vaginosis in females 12 years of age and older. ( 1 )

Vaginal gel (1.3%) containing 65 mg of metronidazole in 5 grams of gel in a pre-filled applicator. Vaginal gel: 65 mg of metronidazole in 5 grams of gel (1.3%) in a prefilled applicator (3)

• History of hypersensitivity to metronidazole, parabens, other ingredients of the formulation, or other nitroimidazole derivatives (4.1)
• Concomitant use of disulfiram or within 2 weeks of disulfiram ( 4.2 , 7.1 )
• Concomitant use of alcohol ( 4.3 , 7.2 )

4.1 Hypersensitivity Metronidazole vaginal gel is contraindicated in persons who have shown hypersensitivity to metronidazole, parabens, other ingredients of the formulation, or other nitroimidazole derivatives.

4.2 Use of Disulfiram Psychotic reactions have been reported with co-administration of disulfiram and oral metronidazole. Do not administer concurrently with or within 2 weeks of disulfiram.

4.3 Concomitant Alcohol Disulfiram-like reactions to alcohol have been reported with co-administration of oral metronidazole; do not consume ethanol or propylene glycol, during and for at least 24 hours following treatment.

• Central and peripheral nervous system effects: Convulsive seizures and peripheral neuropathy have been reported in patients treated with oral or intravenous metronidazole. Discontinue promptly if abnormal neurologic signs develop. ( 5.1 )
• Interference with laboratory tests: Metronidazole may interfere with certain serum chemistry laboratory values. ( 5.3 )

5.1 Central and Peripheral Nervous System Effects Convulsive seizures, encephalopathy, aseptic meningitis, optic and peripheral neuropathy, the latter characterized mainly by numbness or paresthesia of an extremity, have been reported in patients treated with oral or intravenous metronidazole. Metronidazole vaginal gel should be administered with caution to patients with central nervous system diseases. Discontinue promptly if abnormal neurologic signs develop.

5.2 Carcinogenicity in Animals Metronidazole has been shown to be carcinogenic at high doses administered orally in mice and rats [see Nonclinical Toxicology ( 13.1 )] . Unnecessary use of metronidazole should be avoided. Use of Metronidazole vaginal gel should be reserved for the treatment of bacterial vaginosis [see Indications and Usage ( 1 )] .

5.3 Drug/Laboratory Test Interactions Metronidazole may interfere with certain types of determinations of serum chemistry values, such as aspartate aminotransferase (AST, SGOT), alanine aminotransferase (ALT, SGPT), lactate dehydrogenase (LDH), triglycerides, and glucose hexokinase. Values of zero may be observed. All of the assays in which interference has been reported involve enzymatic coupling of the assay to oxidation reduction of nicotinamide-adenine dinucleotides (NAD + NADH). Interference is due to the similarity in absorbance peaks of NADH (340 nm) and metronidazole (322 nm) at pH 7.

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice The most common adverse reactions observed in adult clinical studies (incidence ≥1%) were vulvovaginal candidiasis, headache, vulvovaginal pruritus, nausea, diarrhea, and dysmenorrhea. The most common adverse reactions observed in pediatric clinical studies (incidence ≥1%) was vulvovaginal discomfort. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact. Encube Ethicals Private Limited, at 1-833-285-4151 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1 Clinical Trials Experience Clinical Trial Experience in Adult Patients The safety of metronidazole vaginal gel was evaluated in a randomized, double-blind, vehicle-controlled study in subjects with bacterial vaginosis. A total of 321 non-pregnant females with a mean age of 33.4 years (range 18 to 67 years) received metronidazole vaginal gel. Subjects were primarily Black/African American (58.3%) or White (39.3%).Subjects administered a single dose of metronidazole vaginal gel at bedtime on the first day of the study. There were no deaths or serious adverse reactions in this trial. Adverse reactions were reported by 19.0% of subjects treated with metronidazole vaginal gel versus 16.1% of subjects treated with Vehicle Gel. Adverse reactions occurring in ≥1% of subjects receiving metronidazole vaginal gel were: vulvovaginal candidiasis (5.6%), headache (2.2%), vulvovaginal pruritus (1.6%), nausea (1.6%), diarrhea (1.2%), and dysmenorrhea (1.2%). No subjects discontinued treatment due to adverse reactions. Clinical Trial Experience in Pediatric Patients The safety of metronidazole vaginal gel was evaluated in a multicenter, open-label study evaluating the safety and tolerability of metronidazole vaginal gel in 60 pediatric subjects between the ages of 12 and less than 18 years old all of whom were treated with a single dose of metronidazole vaginal gel administered once at bedtime intravaginally. Most subjects in this study were either Black/African-American, non-Hispanic (47%) or Hispanic (35 %) Safety in pediatric female patients aged 12 to less than 18 years old was comparable to adult women. No deaths occurred and no subjects discontinued due to adverse reactions. Adverse reactions occurring in ≥ 1% of pediatric subjects included: vulvovaginal discomfort (2%).

6.2 Other Metronidazole Formulations Other Vaginal Formulations Other reactions that have been reported in association with the use of other formulations of metronidazole vaginal gel include: unusual taste and decreased appetite. Topical (Dermal) Formulations Other reactions that have been reported in association with the use of topical (dermal) formulations of metronidazole include skin irritation, transient skin erythema, and mild skin dryness and burning. None of these adverse reactions exceeded an incidence of 2% of patients. Oral and Parenteral Formulations The following adverse reactions and altered laboratory tests have been reported with the oral or parenteral use of metronidazole: Cardiovascular: Flattening of the T-wave may be seen in electrocardiographic tracings. Nervous System: The most serious adverse reactions reported in patients treated with oral metronidazole have been convulsive seizures, encephalopathy, aseptic meningitis, optic and peripheral neuropathy, the latter characterized mainly by numbness or paresthesia of an extremity. In addition, patients have reported syncope, vertigo, incoordination, ataxia, confusion, dysarthria, irritability, depression, weakness, and insomnia [see Warnings and Precautions ( 5.1 )]. Gastrointestinal: Abdominal discomfort, nausea, vomiting, diarrhea, an unpleasant metallic taste, anorexia, epigastric distress, abdominal cramping, constipation, “furry” tongue, glossitis, stomatitis, pancreatitis, and modification of taste of alcoholic beverages. Genitourinary: Overgrowth of Candida in the vagina, dyspareunia, decreased libido, proctitis. Hematopoietic: Reversible neutropenia, reversible thrombocytopenia. Hypersensitivity Reactions: Urticaria; erythematous rash; Stevens-Johnson Syndrome, toxic epidermal necrolysis, flushing; nasal congestion; dryness of the mouth, vagina, or vulva; fever; pruritus; fleeting joint pains [see Contraindications ( 4 )]. Renal: Dysuria, cystitis, polyuria, incontinence, a sense of pelvic pressure, darkened urine.

The intravaginal administration of a single dose of metronidazole vaginal gel results in lower systemic exposure to metronidazole that is approximately 2% to 4% of that achieved following oral administration of 500 mg metronidazole tablets [see Clinical Pharmacology ( 12.3 )]. The following drug interactions were reported for oral metronidazole.

• Warfarin and other coumarin anticoagulants: Prolonged anticoagulant effects of warfarin and other coumarin anticoagulants have been reported with co-administration of oral metronidazole. ( 7.3 )
• Lithium: Elevated plasma lithium concentrations have been reported with oral metronidazole. ( 7.4 )

7.1 Disulfiram Use of oral metronidazole has been associated with psychotic reactions in alcoholic patients who are using disulfiram concurrently. Metronidazole vaginal gel should not be used by patients who have taken disulfiram within the last two weeks [see Contraindications ( 4.2 )].

7.2 Alcoholic Beverages Use of oral metronidazole has been associated with a disulfiram-like reaction (abdominal cramps, nausea, vomiting, headaches, and flushing) to alcohol. Alcoholic beverages and preparations containing ethanol or propylene glycol should not be consumed during and for at least 24 hours after metronidazole vaginal gel therapy [see Contraindications ( 4.3 )] .

7.3 Coumarin and Other Oral Anticoagulants Use of oral metronidazole has been reported to potentiate the anticoagulant effect of warfarin and other coumarin anticoagulants, resulting in a prolongation of prothrombin time. This possible drug interaction should be considered when metronidazole vaginal gel is prescribed for patients on this type of anticoagulant therapy.

7.4 Lithium Short-term use of oral metronidazole has been associated with elevation of plasma lithium concentrations and, in a few cases, signs of lithium toxicity in patients stabilized on relatively high doses of lithium.

7.5 Cimetidine Use of oral metronidazole with cimetidine may prolong the half-life and decrease plasma clearance of metronidazole. No dose adjustment of metronidazole vaginal gel is necessary.

Lactation: A lactating patient may pump and discard breastmilk during treatment and for 48 hours after the last dose. ( 8.2 )

8.1 Pregnancy Risk Summary There are no data available on the use of metronidazole vaginal gel in pregnant women. Metronidazole usage in pregnancy has been associated with certain congenital anomalies (see Data ) . In animal reproduction studies, no fetotoxicity or teratogenicity was observed when metronidazole was administered orally to pregnant rats and rabbits, during organogenesis at up to 30 times and 60 times the recommended human dose based on body surface area comparison, respectively (see Data ) . The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Data Human Data Blood levels following metronidazole vaginal administration are lower than those achieved with oral metronidazole. Following a single intravaginal 5 g dose of metronidazole vaginal gel, mean maximum concentration (Cmax) and total exposure (AUC0-∞) are approximately 2% and 4%, respectively, of those following a single oral 500 mg dose of metronidazole tablets [see Clinical Pharmacology ( 12.3 )] . Metronidazole crosses the placental barrier and enters the fetal circulation rapidly. There are published data from case-control studies, cohort studies, and 2 meta-analyses that include more than 5000 pregnant women who used metronidazole during pregnancy. Many studies included first trimester exposures. One study showed an increased risk of cleft lip, with or without cleft palate, in infants exposed to metronidazole in utero; however, these findings were not confirmed . In addition, more than ten randomized placebo-controlled clinical trials enrolled more than 5000 pregnant women to assess the use of antibiotic treatment (including metronidazole) for bacterial vaginosis on the incidence of preterm delivery. Most studies did not show an increased risk for congenital anomalies or other adverse fetal outcomes following metronidazole exposure during pregnancy . Three studies conducted to assess the risk of infant cancer following metronidazole exposure during pregnancy did not show an increased risk; however, the ability of these studies to detect such a signal was limited . Animal Data No fetotoxicity or teratogenicity was observed when metronidazole was administered orally to pregnant rabbits at up to 200 mg/kg (about 60 times the maximum human dose based on body surface area comparison). Similarly, no fetotoxic or teratogenic effects were observed in five studies in rats where dosing was administered orally in the diet or by gastric intubation at doses up to 200 mg/kg (about 30 times the maximum human dose based on body surface area comparison). As well, no fetotoxicity or teratogenicity was observed when metronidazole was administered orally to pregnant mice at doses up to 100 mg/kg (about 7 times the maximum human dose based on body surface area comparison). However, some intrauterine deaths were observed in Swiss Webster mice administered metronidazole intraperitoneally at doses up to 15 mg/kg (about 1 times the maximum human dose based on body surface area comparison). The relationship of these intraperitoneal findings in mice to the vaginal use of metronidazole vaginal gel is unknown.

8.2 Lactation Risk Summary There are no data on the presence of metronidazole in human milk following intravaginal administration. Metronidazole is present in human milk following oral metronidazole administration, at concentrations similar to those found in plasma ( see Data ). The metronidazole vaginal gel achieves 2% of the mean maximum serum concentration of a 500 mg oral metronidazole dose [see Clinical Pharmacology ( 12.3 )]. The published literature reports no adverse effects in infants exposed through breastmilk to maternal orally administered metronidazole. There are no data on the effects on milk production. Animal studies have shown the potential for tumorigenicity after oral metronidazole was administered chronically to rats and mice [see Nonclinical Toxicology ( 13.1 )]. The clinical relevance of these findings is unclear. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for metronidazole vaginal gel, and any potential adverse effects on the breastfed child from metronidazole gel or from the underlying maternal condition. Alternatively, a lactating patient may interrupt breastfeeding and choose to pump and discard breastmilk during treatment with metronidazole vaginal gel and for 48 hours after the last dose and feed her infant previously stored human milk or formula. Data In a study of lactating women receiving oral metronidazole 600 mg (n=11) or 1200 mg (n=4) daily, mean maternal plasma concentrations were 5.0 and 12.5 mcg/mL respectively, within 2 hours following administration; the milk: maternal plasma ratio was approximately 1.

8.4 Pediatric Use The safety and effectiveness of metronidazole vaginal gel have been established in pediatric subjects between the ages of 12 and less than 18 years old. Use of metronidazole vaginal gel in this age group is supported by evidence from a multicenter, open-label safety and tolerability study in 60 pediatric patients with bacterial vaginosis [see Adverse Reactions ( 6.1 )] and, evidence from adequate and well-controlled studies in adult women. The safety and effectiveness of metronidazole vaginal gel in pediatric subjects below the age of 12 years have not been established.

8.5 Geriatric Use Clinical studies with metronidazole vaginal gel did not include sufficient numbers of subjects 65 years of age or older to determine whether they respond differently than younger subjects.

Metronidazole is an antimicrobial drug [see Microbiology ( 12.4 )] .