FULVICIN-U/F
Clinical safety rating: caution
Comprehensive clinical and safety monograph for FULVICIN-U/F (FULVICIN-U/F).
Inhibition of fungal cell mitosis by binding to microtubules, disrupting spindle formation and nuclear division.
| Metabolism | Hepatic oxidation via CYP450 enzymes (primarily CYP3A4), producing inactive metabolites. |
| Excretion | Primarily hepatic metabolism; <1% excreted unchanged in urine; metabolites excreted in bile and feces. |
| Half-life | Terminal half-life approximately 9.5 hours; may be prolonged in liver disease. |
| Protein binding | Approximately 97% bound to plasma proteins (mainly albumin). |
| Volume of Distribution | Apparent volume of distribution is 0.5 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral bioavailability is 35-70% due to variable absorption from the gastrointestinal tract (enhanced with high-fat meals). |
| Onset of Action | Onset of action is slow; clinical improvement in dermatophyte infections typically seen after 2-3 weeks of oral therapy. |
| Duration of Action | Duration of action is prolonged; drug persists in skin, hair, and nails for up to 2 weeks after cessation, aiding in eradication of fungi. |
125 mg orally once daily with a high-fat meal for 7 days, then 125 mg every other day for 7 days (total 13 doses).
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for renal impairment; pharmacokinetics not significantly affected. |
| Liver impairment | Contraindicated in Child-Pugh class C; for class A or B, use with caution and monitor liver function; no specific dose reduction guidelines. |
| Pediatric use | Not recommended for use in children due to lack of safety and efficacy data. |
| Geriatric use | No specific dose adjustment; use with caution due to potential age-related renal and hepatic decline; monitor for adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for FULVICIN-U/F (FULVICIN-U/F).
| Breastfeeding | Griseofulvin is excreted into breast milk. The M/P ratio is approximately 0.5. The amount ingested by a nursing infant is likely subtherapeutic but may cause adverse effects (e.g., diarrhea, rash). Caution is advised; consider alternative therapies or temporarily discontinue breastfeeding during treatment. |
| Teratogenic Risk | Pregnancy Category X. Griseofulvin is contraindicated in pregnant women and women who may become pregnant. Animal studies have demonstrated teratogenic and embryotoxic effects (e.g., skeletal abnormalities, cleft palate) in multiple species. There is no adequate human data; therefore, fetal risk cannot be excluded. Use during the first trimester carries the highest risk. Effective contraception should be used during and for 1 month after therapy. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to griseofulvin or any component; porphyria; severe liver disease; pregnancy (category C); caution with alcohol.
| Precautions | Hepatotoxicity (monitor liver function); photosensitivity (avoid prolonged sun exposure); caution in alcoholics or liver disease; possible exacerbation of porphyria; lupus-like syndrome; hypersensitivity reactions. |
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| Fetal Monitoring | Monitor liver function tests (AST, ALT, alkaline phosphatase) periodically due to potential hepatotoxicity. Monitor renal function (BUN, creatinine) if renal impairment suspected. Assess for hypersensitivity reactions (rash, urticaria). In pregnant patients (if inadvertently exposed), perform a fetal ultrasound to assess for structural anomalies. |
| Fertility Effects | Griseofulvin has been shown to cause testicular atrophy and reduced spermatogenesis in animal studies. In humans, impaired fertility has been reported, particularly with long-term use. It may also interfere with oral contraceptive efficacy via enzyme induction (CYP3A4). Patients planning pregnancy should discontinue therapy and use alternative contraception. |