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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VANDAZOLE (VANDAZOLE).
| Breastfeeding | Metronidazole is excreted into human breast milk. Following a single 2 g oral dose, the milk-to-plasma (M/P) ratio is approximately 1.0. However, vaginal administration results in lower systemic absorption (plasma levels ~2% of oral dose), leading to negligible infant exposure. The American Academy of Pediatrics considers metronidazole compatible with breastfeeding when used vaginally. Caution is advised if oral metronidazole is used concurrently. |
| 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. |
■ 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 nitroimidazoles; first trimester of pregnancy (unless other treatment options are not available); concomitant use with disulfiram (within 2 weeks) or alcohol-containing products.
| 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. |
Loading safety data…
| 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. |