FEMSTAT 3
Clinical safety rating: caution
Comprehensive clinical and safety monograph for FEMSTAT 3 (FEMSTAT 3).
Butoconazole nitrate, an imidazole antifungal, inhibits fungal cytochrome P450 14α-demethylase, preventing ergosterol synthesis and disrupting fungal cell membrane integrity.
| Metabolism | Minimal systemic absorption; primarily metabolized in the liver via oxidation and conjugation. |
| Excretion | Following topical vaginal administration of butoconazole nitrate, approximately 5% of the dose is absorbed systemically. The absorbed fraction is primarily metabolized in the liver and excreted via the biliary/fecal route. Renal excretion accounts for less than 3% of the administered dose. |
| Half-life | The terminal elimination half-life of butoconazole following topical vaginal administration is approximately 21-24 hours. This prolonged half-life supports once-daily dosing for 3 days in the treatment of vulvovaginal candidiasis. |
| Protein binding | Butoconazole is extensively bound to plasma proteins, primarily albumin, with a binding of approximately 98-99%. |
| Volume of Distribution | Due to low systemic absorption after topical vaginal administration, the volume of distribution (Vd) for the absorbed fraction is not well characterized. However, based on systemic studies of similar azole antifungals, the apparent Vd is estimated to be large (> 200 L), indicating extensive tissue distribution. For topical vaginal use, the local Vd is not clinically relevant. |
| Bioavailability | The systemic bioavailability of butoconazole after topical vaginal administration is approximately 5% (range 1-10%). This low systemic absorption minimizes systemic side effects while maintaining high local concentrations for antifungal efficacy. |
| Onset of Action | Clinical improvement (reduction in symptoms such as itching, burning, and discharge) is typically observed within 24-72 hours after initiating therapy. However, symptomatic relief may begin as early as 12-24 hours after the first dose. |
| Duration of Action | The therapeutic effect, as measured by mycological cure, persists for the 3-day treatment course and beyond. With once-daily dosing for 3 days, clinical cure rates are approximately 80-90% at 1-2 weeks post-treatment. The drug provides sustained local antifungal activity at the vaginal mucosa for the duration of treatment. |
| Molecular Weight | 440.55 Da (as butoconazole nitrate; base: 377.9 Da) |
Intravaginal cream: 1 applicatorful (5 g of 2% butoconazole nitrate) intravaginally at bedtime for 3 consecutive days.
| Dosage form | CREAM |
| Renal impairment | No dose adjustment required for renal impairment; pharmacokinetics not significantly altered by decreased GFR. |
| Liver impairment | No specific dose adjustment guidelines available for hepatic impairment; use caution in severe hepatic disease. |
| Pediatric use | Pediatric (≥12 years): same as adult dosing (intravaginal cream 2% once daily for 3 days). Safety and efficacy not established for children <12 years. |
| Geriatric use | No specific dose adjustment required; use same as adult dosing. Consider age-related genital mucosal atrophy and potential for increased systemic absorption in elderly. |
| 1st trimester | Butoconazole is categorized as pregnancy category C. There are no adequate and well-controlled studies in pregnant women. Use only if clearly needed and potential benefit justifies risk to the fetus. Intravaginal use is preferred due to minimal systemic absorption. |
| 2nd trimester | Limited data suggest no increased risk of major malformations. Consider avoidance during second trimester unless necessary; Intravaginal use is preferred. |
| 3rd trimester | Avoid use near term (after 37 weeks) as vaginal antifungal therapy may be associated with an increased risk of preterm birth in some studies. Intravaginal use is preferred if clinically necessary. |
Clinical note
Comprehensive clinical and safety monograph for FEMSTAT 3 (FEMSTAT 3).
| Placental transfer | Negligible placental transfer due to low systemic absorption after intravaginal administration. No specific data on placental crossing. |
| Breastfeeding |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to butoconazole, other imidazoles, or any component of the formulation
| Precautions | For intravaginal use only; not for ophthalmic or oral use., Discontinue if hypersensitivity or irritation occurs., Avoid use during menstruation., May weaken latex condoms or diaphragms; use alternative contraception for 72 hours after treatment. |
| Food/Dietary | No clinically significant food interactions. Grapefruit juice does not interact with topical butoconazole. Alcohol consumption is not contraindicated but may increase vaginal irritation in some patients. |
| Clinical Pearls |
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| Butoconazole is minimally absorbed after intravaginal administration (<2% bioavailability). It is expected that systemic concentrations in breast milk are negligible. Caution is advised with prolonged application near the nipple area. The manufacturer recommends caution during breastfeeding. |
| Lactation Rating | L2 (Probably Compatible) - Limited data, minimal absorption. |
| Teratogenic Risk | Butoconazole nitrate is an azole antifungal for intravaginal use. Systemic absorption is minimal (approximately 1.7%), thus fetal exposure is negligible. No teratogenic effects have been observed in animal studies at doses up to 100 mg/kg/day. Pregnancy Category C: Insufficient human data; use only if clearly needed. First trimester: Avoid unless potential benefit outweighs risk. Second and third trimesters: Considered safe for use; no increased risk of major birth defects reported. |
| Fetal Monitoring | No specific fetal monitoring required. Monitor for local irritation or hypersensitivity reactions. If clinical signs of systemic infection occur (fever, chills), evaluate for alternative diagnosis. In pregnancy, monitor for persistence of symptoms; repeat cultures if symptoms do not resolve. |
| Fertility Effects | No known adverse effects on fertility. Animal studies have not shown impaired fertility at therapeutic doses. Butoconazole is used locally for vulvovaginal candidiasis and does not affect ovulation or conception when used as directed. |
| FEMSTAT 3 (butoconazole nitrate 2% vaginal cream) is a topical azole antifungal for vulvovaginal candidiasis. It requires only a 3-day regimen, which may improve adherence. Avoid use during first trimester of pregnancy unless clearly necessary; it is pregnancy category C. Do not use with intravaginal devices such as tampons or diaphragms during treatment. If symptoms persist beyond 7 days, re-evaluate for alternative diagnoses including resistant Candida or bacterial vaginosis. |
| Patient Advice | Use the applicator to insert one full applicator dose into the vagina at bedtime for 3 consecutive nights. · Wash hands before and after insertion; clean applicator with soap and water after each use. · Do not use tampons, douches, spermicides, or other vaginal products during treatment. · Avoid sexual intercourse during treatment and for 3 days after therapy to allow healing. · Continue using cream even if menstruation starts; do not skip doses. · Inform your healthcare provider if you are pregnant, breastfeeding, or have diabetes. · Seek medical attention if symptoms worsen, or if you experience severe abdominal pain, chills, or fever. · Avoid tight-fitting synthetic underwear; wear cotton underwear to promote healing. |