FULVICIN P/G
Clinical safety rating: caution
Comprehensive clinical and safety monograph for FULVICIN P/G (FULVICIN P/G).
Binds to microtubule-associated proteins, disrupting mitotic spindle formation and inhibiting fungal cell division.
| Metabolism | Hepatic metabolism primarily via CYP enzymes, including CYP1A2 and CYP3A4 |
| Excretion | Renal (largely unchanged, <1% as metabolites); biliary/fecal (minor). Approximately 36% of a dose is excreted in urine within 6 hours, and up to 50% within 72 hours. |
| Half-life | Terminal elimination half-life: 9–24 hours (mean ~16 hours). Clinical context: prolonged half-life allows once-daily dosing; steady-state achieved within 2–3 days. |
| Protein binding | Highly protein-bound: approximately 97–99%, primarily to albumin. |
| Volume of Distribution | Vd: approximately 1.0 L/kg, indicating extensive tissue distribution, particularly to skin, hair, and nails. |
| Bioavailability | Oral: bioavailable fraction highly variable (20–80%) due to poor aqueous solubility and first-pass metabolism; absorption enhanced with fatty meals. |
| Onset of Action | Oral: detectable epidermal levels in 4–8 hours; clinical improvement of tinea infections usually within 2–4 weeks. |
| Duration of Action | Duration: up to 7 days after last dose due to accumulation in keratin; continued treatment required for 4–8 weeks for most dermatophyte infections. |
| Molecular Weight | 352.77 |
250 mg orally twice daily for tinea infections; 500 mg orally twice daily for onychomycosis. Administer with a fatty meal to enhance absorption.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. For severe impairment (GFR <30 mL/min), consider alternative therapy due to limited data; use with caution. |
| Liver impairment | Contraindicated in patients with Child-Pugh class B or C cirrhosis. For Child-Pugh class A, reduce dose by 50% and monitor liver function. |
| Pediatric use | For children ≥2 years: 10 mg/kg/day orally in divided doses (twice daily) for tinea infections; up to 20 mg/kg/day for severe infections. Maximum 1 g/day. |
| Geriatric use | No specific dose adjustment. Monitor renal and hepatic function due to age-related decline; consider lower end of dosing range to avoid accumulation. |
| 1st trimester | Avoid use. Griseofulvin is teratogenic in animals; human data limited. Contraindicated in pregnancy. |
| 2nd trimester | Avoid use. Risk of fetal abnormalities; contraindicated in pregnancy. |
| 3rd trimester | Avoid use. Potential for fetal harm; contraindicated in pregnancy. |
Clinical note
Comprehensive clinical and safety monograph for FULVICIN P/G (FULVICIN P/G).
| Placental transfer | Griseofulvin crosses the placenta in animals; human data limited but presumed. |
| Breastfeeding | Griseofulvin is excreted into human milk. Due to potential for adverse effects in nursing infants (e.g., hepatotoxicity, carcinogenesis), breastfeeding is not recommended during therapy. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Serious Effects |
PregnancyPorphyriaHepatocellular failureHypersensitivity to griseofulvin
| Precautions | Hepatotoxicity, Photosensitivity reactions, Lupus erythematosus exacerbation, Hematologic effects (leukopenia, neutropenia), Monitoring hepatic function recommended |
| Food/Dietary | Absorption is significantly increased with high-fat meals. Avoid alcohol. No specific food restrictions beyond ensuring adequate fat intake for absorption. |
| Clinical Pearls | FULVICIN P/G (griseofulvin) is a fungistatic agent used for dermatophyte infections. It is not effective against Candida or bacteria. Administer with fatty meals to enhance absorption. Monitor for hepatotoxicity and photosensitivity. Avoid in porphyria and severe liver disease. Check for drug interactions with warfarin (increases INR), oral contraceptives (reduces efficacy), and phenobarbital (decreases griseofulvin levels). |
Loading safety data…
| L5 (Avoid) |
| Teratogenic Risk | FULVICIN P/G (griseofulvin) is contraindicated in pregnancy. First trimester: High risk of teratogenicity based on animal studies (multiple congenital anomalies, including conjoined twins in dogs). Second and third trimesters: Avoid due to potential fetal harm; no well-controlled human studies. Consider alternative therapy. |
| Fetal Monitoring | Monitor maternal liver function tests (LFTs), complete blood count (CBC) with differential, and renal function periodically. Assess for signs of hepatotoxicity or blood dyscrasias. Fetal monitoring with ultrasound if inadvertent exposure during pregnancy. |
| Fertility Effects | Animal studies show reduced spermatogenesis and testicular changes at high doses; human data limited. May impair fertility in males. Effects on female fertility not well characterized. |
| Patient Advice | Take this medication with a fatty meal (e.g., milk, ice cream) to improve absorption. · Complete the full course of treatment even if symptoms improve. · Avoid prolonged sun exposure and use sunscreen due to increased risk of photosensitivity. · Report signs of liver problems: yellowing of skin/eyes, dark urine, fatigue. · Inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding. · This medication may reduce the effectiveness of oral contraceptives; use additional birth control methods. · Avoid alcohol as it may increase risk of liver toxicity. |