MICONAZOLE 3
Clinical safety rating: safe
Warfarin metabolism is inhibited increasing INR For topical use only not for ophthalmic use.
Miconazole inhibits fungal cytochrome P450 14α-demethylase (CYP51), thereby blocking the conversion of lanosterol to ergosterol, an essential component of the fungal cell membrane. This leads to increased membrane permeability, leakage of cellular contents, and fungal cell death.
| Metabolism | Miconazole is primarily metabolized in the liver via oxidative pathways, including CYP3A4-mediated metabolism. The main metabolites are inactive and excreted in feces and urine. Topical absorption is minimal (<1%), reducing systemic metabolism. |
| Excretion | Primarily hepatic metabolism; <1% excreted unchanged in urine; fecal elimination accounts for ~50% of metabolites. |
| Half-life | Terminal half-life is approximately 24 hours (range 20-30 hours) following topical vaginal application; prolonged in hepatic impairment. |
| Protein binding | ~90% bound primarily to albumin. |
| Volume of Distribution | 0.25-0.5 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Systemic absorption from vaginal administration is minimal (~1.4%); oral bioavailability is low (~25-30%) due to extensive first-pass metabolism. |
| Onset of Action | Vaginal administration: clinical improvement within 1-3 days; maximal effect by 7 days. |
| Duration of Action | Single vaginal dose provides therapeutic levels for 3-5 days; typical treatment course is 3-7 days. |
| Molecular Weight | 416.13 |
For vaginal candidiasis: 200 mg (one suppository) intravaginally at bedtime for 3 consecutive days.
| Dosage form | CREAM |
| Renal impairment | No dosage adjustment required for renal impairment. |
| Liver impairment | Mild to moderate hepatic impairment (Child-Pugh A or B): no adjustment necessary. Severe hepatic impairment (Child-Pugh C): insufficient data; consider alternative therapy. |
| Pediatric use | Not recommended for pediatric patients; safety and efficacy not established. |
| Geriatric use | No specific dosage adjustment; use standard adult dosing with caution due to potential comorbidities. |
| 1st trimester | Generally considered safe when used topically in recommended doses; limited systemic absorption. Avoid high-dose intravaginal use unless clearly needed. |
| 2nd trimester | Generally considered safe; minimal systemic absorption. Intravaginal use not associated with teratogenic risk. |
| 3rd trimester | Generally considered safe; use near term may increase risk of neonatal mucocutaneous candidiasis if high doses used. Avoid in third trimester unless benefit outweighs risk. |
Clinical note
Warfarin metabolism is inhibited increasing INR For topical use only not for ophthalmic use.
| FDA category | Human |
| Placental transfer | Low placental transfer; limited systemic absorption after topical or intravaginal administration. Significant transfer unlikely with standard doses. |
■ FDA Black Box Warning
None
| Common Effects | vaginal yeast infections |
| Serious Effects |
Hypersensitivity to miconazole or any component of the formulation
| Precautions | For external use only; avoid contact with eyes, mouth, or vagina (unless using vaginal formulation)., May cause hypersensitivity reactions including contact dermatitis; discontinue if irritation or sensitization occurs., Potential for cross-sensitivity with other azole antifungals., Use with caution in patients with hepatic impairment due to potential systemic absorption., Do not use occlusive dressings unless directed; may increase systemic absorption and adverse effects. |
| Food/Dietary | No known food interactions. Avoid alcohol during treatment due to potential disulfiram-like reaction (rare with topical use, theoretical). |
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| Breastfeeding |
| Minimal systemic absorption after topical or intravaginal use; not expected to cause adverse effects in breastfed infants. Oral gel forms should be used with caution due to potential infant ingestion. |
| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | Miconazole is an azole antifungal. Based on limited human data, there is no evidence of increased risk of major birth defects with topical or intravaginal use. For oral or intravenous use, avoid in first trimester unless benefit outweighs risk. In animal studies, high systemic doses caused fetal toxicity. No known association with specific malformations. |
| Fetal Monitoring | No specific monitoring required for topical or intravaginal use. For systemic use, monitor liver function tests (LFTs) and renal function. Assess for signs of hepatotoxicity or hypersensitivity. |
| Fertility Effects | No known adverse effects on fertility from standard topical or intravaginal doses. Systemic high doses may impair spermatogenesis or ovulation in animal studies at high doses, but data in humans are lacking for fertility. |
| Clinical Pearls | For intravaginal use only; not for oral or ophthalmic. Avoid use of tampons, douches, spermicides, or other vaginal products during treatment. Discontinue if hypersensitivity occurs. Use caution in patients with diabetes or immunocompromised states. May weaken latex condoms and diaphragms. |
| Patient Advice | Use at bedtime for 7 consecutive days for optimal efficacy. · Complete full course even if symptoms improve early. · Avoid sexual intercourse during treatment. · Do not use tampons; use sanitary pads instead. · Report persistent symptoms or vaginal irritation to healthcare provider. · If pregnant or breastfeeding, consult healthcare provider before use. |