VANDAZOLE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VANDAZOLE (VANDAZOLE).
VANDAZOLE is a nitroimidazole antimicrobial agent that undergoes reduction by bacterial nitroreductases, forming cytotoxic free radicals that damage DNA and inhibit nucleic acid synthesis.
| Metabolism | Primarily hepatic via CYP450 enzymes (including CYP2A6, CYP3A4, and CYP2C9) with glucuronidation; major metabolite is 2-hydroxymethyl metronidazole. |
| Excretion | Primarily renal (40-70% unchanged), with biliary/fecal elimination accounting for 15-20% as metabolites. |
| Half-life | Approximately 8-10 hours in adults; prolonged to 20-25 hours in hepatic impairment. |
| Protein binding | Approximately 20% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | 0.5-0.8 L/kg, indicating distribution into total body water and moderate tissue penetration. |
| Bioavailability | Oral: 90-100%; topical: approximately 10% systemic absorption. |
| Onset of Action | Intravenous: within 2-4 hours; oral: 24-48 hours; topical: 2-4 weeks for clinical response. |
| Duration of Action | 12-24 hours after single IV dose; clinical effect persists for 24-48 hours; topical therapy requires 2-4 weeks for sustained effect. |
| Molecular Weight | 171.15 |
2 g orally as a single dose once daily for 2 days.
| Dosage form | GEL |
| Renal impairment | No adjustment required for mild to moderate renal impairment. For severe renal impairment (CrCl <10 mL/min), not recommended. |
| Liver impairment | Child-Pugh Class A and B: No adjustment. Child-Pugh Class C: Avoid use due to lack of data. |
| Pediatric use | Weight-based: 25 mg/kg orally as a single dose once daily for 2 days; maximum 2 g per dose. |
| Geriatric use | No specific dose adjustment recommended; use with caution due to potential for reduced hepatic and renal function. |
| 1st trimester | Contraindicated due to teratogenicity in animal studies; avoid use in first trimester. |
| 2nd trimester | Use only if clearly needed; potential risk of fetal harm based on animal data. |
| 3rd trimester | Avoid near term due to possible risk of neonatal hemolysis (if G6PD deficient) or kernicterus. |
Clinical note
Comprehensive clinical and safety monograph for VANDAZOLE (VANDAZOLE).
| Placental transfer | Crosses placenta readily; achieves fetal serum levels similar to maternal. |
| Breastfeeding | Excreted into breast milk in small amounts; caution with prolonged therapy; monitor infant for diarrhea or oral thrush. |
| Lactation Rating |
■ FDA Black Box Warning
Carcinogenicity: Vandazole has been shown to be carcinogenic in mice and rats. Avoid chronic use unless necessary.
| Serious Effects |
Hypersensitivity to metronidazole or other nitroimidazole derivativesFirst trimester of pregnancy (unless alternative not available and life-threatening infection)Concurrent use with disulfiram or ethanol (potential disulfiram-like reaction)
| Precautions | May cause peripheral neuropathy (paresthesias, seizures) with prolonged therapy; discontinue if neurological symptoms occur. Use with caution in patients with CNS conditions, hepatic impairment, or history of blood dyscrasias. Prolonged use may result in candidiasis. Avoid alcohol during therapy and for 48 hours after due to disulfiram-like reaction. |
| Food/Dietary | Avoid alcohol and any products containing alcohol or propylene glycol during treatment and for 48 hours after the last dose. No specific food interactions noted. |
Loading safety data…
| L3 (Moderately Safe) |
| Teratogenic Risk | Vandazole (metronidazole vaginal gel) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated teratogenic effects, but there are no adequate and well-controlled studies in pregnant women. Use during pregnancy should be reserved for cases where clearly needed, especially during the first trimester due to theoretical risk. However, CDC and ACOG consider metronidazole safe for use in all trimesters for treatment of bacterial vaginosis. |
| Fetal Monitoring | No specific fetal monitoring is required with vaginal metronidazole due to minimal systemic absorption. However, if used orally or intravenously in pregnancy, monitoring for maternal adverse effects (e.g., gastrointestinal, neurological) and fetal growth via ultrasound may be considered. No routine drug level monitoring is needed. |
| Fertility Effects | There is no evidence that Vandazole (metronidazole vaginal gel) adversely affects female or male fertility. Animal studies with oral metronidazole have shown no impairment of fertility. In humans, no fertility-related adverse effects have been reported with vaginal administration. |
| Clinical Pearls | Vandazole (metronidazole vaginal gel) is indicated for bacterial vaginosis. Administer one full applicator intravaginally once or twice daily for 5 days. Avoid alcohol during therapy and for 48 hours after last dose due to disulfiram-like reaction. May cause metallic taste, even with topical use. Not effective for trichomoniasis or candidiasis. |
| Patient Advice | Use the gel exactly as prescribed, usually once or twice daily for 5 days. · Wash applicator with mild soap and water after each use. · Avoid sexual intercourse or use condoms during treatment. · Do not drink alcohol or use alcohol-containing products during treatment and for 48 hours after the last dose. · You may experience a metallic taste in your mouth; this is normal. · Seek medical attention if you experience severe abdominal pain, vomiting, or signs of allergic reaction. |