ECONAZOLE NITRATE
Clinical safety rating: safe
Animal studies have demonstrated safety
Econazole nitrate, an imidazole antifungal, inhibits fungal cytochrome P450 14α-demethylase (CYP51), blocking ergosterol synthesis, disrupting fungal cell membrane integrity and function.
| Metabolism | Hepatic metabolism primarily via CYP3A4 and CYP2C9 |
| Excretion | Primarily hepatic metabolism; <1% unchanged in urine; 30-45% in feces as metabolites; minimal biliary excretion. |
| Half-life | Terminal elimination half-life approximately 8-10 hours; clinical relevance: supports twice-daily topical dosing for sustained antifungal effect. |
| Protein binding | Approximately 98% bound, primarily to albumin. |
| Volume of Distribution | Approximately 2.5 L/kg, indicating extensive tissue distribution (e.g., skin, mucosa). |
| Bioavailability | Topical: negligible systemic absorption (<1% of applied dose); vaginal: approximately 5-10% absorbed systemically; oral: not available (not administered systemically). |
| Onset of Action | Topical: clinical improvement (e.g., reduction of erythema, scaling) typically noted within 24-72 hours; in vaginal candidiasis, symptom relief often begins within 1-3 days. |
| Duration of Action | Topical: antifungal activity persists for 24 hours after single application, with clinical cure typically requiring 2-4 weeks of daily therapy for dermatophytosis; vaginal cream: effects last 1-3 days post-dose, often requiring single-dose or 3-day regimen. |
Topical: Apply a thin layer to affected area twice daily (morning and evening). Vaginal: One applicatorful (150 mg) intravaginally at bedtime for 3 days. Rectal candidiasis: One 150 mg suppository rectally at bedtime for 3 days.
| Dosage form | CREAM |
| Renal impairment | No dosage adjustment required for renal impairment. Systemic absorption is minimal with topical application. |
| Liver impairment | No dosage adjustment required for hepatic impairment; topical use with minimal systemic absorption. No Child-Pugh data available; use with caution in severe hepatic impairment due to theoretical risk. |
| Pediatric use | Topical: Apply 2-3 times daily for 7-10 days; safety not established for intravaginal use. For diaper dermatitis: Apply thin layer with each diaper change. |
| Geriatric use | No specific dose adjustment; use same as adult dosing. Consider skin fragility with topical application; monitor for local irritation. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions For topical use only not for ophthalmic use.
| Breastfeeding | It is unknown if econazole is excreted in human milk after topical application. The manufacturer recommends caution during breastfeeding. Due to minimal systemic absorption, it is unlikely to reach significant levels in breast milk. The M/P ratio has not been determined. Use on the breast should be avoided to prevent infant ingestion. Consider an alternative antifungal agent if prolonged therapy is needed. |
| Teratogenic Risk | Econazole nitrate is classified as FDA Pregnancy Category C. Animal studies have shown embryotoxicity and fetotoxicity at high oral doses, but no teratogenicity. There are no adequate and well-controlled studies in pregnant women. The drug should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Systemic absorption after topical application is minimal (<10%), so risk to the developing fetus is considered low when used as directed. No specific first-trimester risks have been identified; however, use should be limited to short-term treatment of superficial infections. |
■ FDA Black Box Warning
None
| Common Effects | Skin irritation |
| Serious Effects |
Hypersensitivity to econazole nitrate, other imidazoles, or any component of the formulation
| Precautions | For external use only; avoid contact with eyes, nose, mouth, or other mucous membranes. If irritation or hypersensitivity develops, discontinue use. Not for ophthalmic or oral use. Use during pregnancy only if clearly needed (limited data). |
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| Fetal Monitoring | No specific maternal or fetal monitoring is required for topical use. Monitor for local irritation or allergic reaction at application site. If oral ingestion occurs, monitor for gastrointestinal symptoms (nausea, vomiting, diarrhea) and hepatic function due to potential hepatotoxicity from prolonged systemic exposure, though unlikely with topical use. |
| Fertility Effects | Animal studies with oral econazole showed impaired fertility and prolonged estrus cycles at high doses. No human data are available. It is not expected to affect fertility when used topically due to minimal systemic absorption. Reversible fertility impairment has not been reported in humans. |