Griseofulvin-FP

Griseofulvin [Microsize] is an antifungal agent indicated for superficial fungal infections of the skin, hair, and nails caused by dermatophytes.

Approved Indications:

• Tinea capitis (scalp ringworm): Effective against Trichophyton species causing hair and scalp infections.
• Tinea corporis (ringworm of the body): Superficial dermatophyte infections of glabrous skin.
• Tinea cruris (jock itch): Dermatophyte infections of the groin and adjacent areas.
• Tinea pedis (athlete’s foot): Chronic or recurrent infections caused by dermatophytes.
• Onychomycosis (nail fungal infection): Limited efficacy; usually for nail involvement due to Trichophyton species.

Clinically Accepted Off-Label Uses:

• Prevention of recurrent dermatophyte infections in high-risk populations.
• Adjunct therapy for refractory fungal infections not responding to topical agents.

Adults:

• Microsize griseofulvin: 500 mg orally once daily or 250 mg twice daily.
• Duration:
• Tinea capitis: 6–8 weeks
• Tinea corporis/cruris/pedis: 4–6 weeks
• Onychomycosis: 3–6 months (depending on nail involvement)

Pediatrics:

• Microsize griseofulvin: 10–20 mg/kg/day orally in divided doses.
• Duration:
• Tinea capitis: 6–12 weeks
• Other dermatophyte infections: 4–8 weeks

Elderly:

• Standard dosing; monitor for hepatic function and drug interactions.

Special Populations:

• Renal impairment: No dose adjustment required; excretion is primarily hepatic.
• Hepatic impairment: Use with caution; monitor liver function.

Administration Notes:

• Take with fatty meals or milk to enhance absorption.
• Swallow tablets whole; do not crush or chew.

Griseofulvin [Microsize] inhibits fungal mitosis by binding to fungal microtubules, disrupting the mitotic spindle formation. This prevents cell division and inhibits fungal growth. Griseofulvin also binds to keratin in skin, hair, and nails, making newly formed keratin resistant to fungal invasion. Over time, infected keratin is replaced with drug-protected keratin, eradicating the infection.

• Absorption: Poorly absorbed orally; microsize formulation improves bioavailability.
• Distribution: Concentrates in keratin-rich tissues (skin, hair, nails).
• Protein Binding: ~90%.
• Metabolism: Hepatic metabolism via CYP450 enzymes (mainly CYP3A4).
• Active Metabolites: Not clinically significant.
• Excretion: Primarily via bile and feces; minor renal excretion.
• Half-Life: 9–12 hours
• Onset: Clinical improvement often observed after several weeks due to slow keratin turnover.

• Pregnancy: Category X — contraindicated; griseofulvin is teratogenic and may cause fetal malformations. Effective contraception is recommended during treatment.
• Lactation: Excreted in breast milk; breastfeeding not recommended during therapy.
• Note: Women of childbearing potential should avoid pregnancy during and for at least one month after therapy.

• Primary Class: Antifungal
• Subclass: Systemic dermatophyte agent

• Known hypersensitivity to griseofulvin or any excipients.
• Pregnancy (teratogenic risk).
• Severe hepatic impairment.
• Porphyria or history of porphyric disorders.

• High-risk patients:
• Hepatic dysfunction — monitor liver function tests.
• Porphyria — may precipitate attacks.
• Systemic lupus erythematosus — caution due to potential exacerbation.
• Serious risks:
• Hepatotoxicity, neutropenia, or severe dermatologic reactions (rare).
• Photosensitivity — patients should avoid prolonged sun exposure.
• Monitoring:
• Liver function tests for long-term therapy.
• Complete blood count if therapy exceeds 4–6 weeks.
• Early signs of hypersensitivity: rash, fever, jaundice.

Common:

• Headache
• Gastrointestinal upset (nausea, vomiting, diarrhea)
• Fatigue
• Mild rash

Serious/Rare:

• Hepatotoxicity (elevated liver enzymes, jaundice)
• Neutropenia or leukopenia
• Photosensitivity reactions
• Exacerbation of porphyria
• Severe allergic reactions (rare)

• Drug-Drug:
• Reduces efficacy of warfarin — monitor INR.
• Reduces effectiveness of oral contraceptives — use alternative contraception.
• Induces CYP450 enzymes, potentially reducing efficacy of other drugs metabolized via CYP3A4.
• Drug-Food: High-fat meals improve absorption.
• Drug-Alcohol: Avoid alcohol — may increase hepatotoxicity risk.
• Enzyme Systems: CYP3A4 induction; affects metabolism of co-administered drugs.

• Current guidelines: Microsize griseofulvin preferred over ultramicrosize for improved absorption and efficacy.
• Safety: Emphasis on avoiding use in pregnancy and monitoring liver function during prolonged therapy.
• Treatment recommendations: Duration of therapy tailored to site of infection; tinea capitis typically requires 6–12 weeks, while nail infections may require months of therapy.

• Store at 20°C–25°C (room temperature).
• Protect from moisture and light.
• Keep container tightly closed.
• Do not freeze.
• Keep out of reach of children.