Grifulvin V (griseofulvin microsize) is an oral antifungal agent specifically formulated for the systemic treatment of dermatophyte infections that are unresponsive to topical therapy. As a fungistatic antibiotic derived from Penicillium griseofulvum, it works by depositing in newly forming skin, hair, and nails, binding to keratin and protecting it from fungal invasion. It is the therapeutic cornerstone for tinea infections of the scalp (tinea capitis), body (tinea corporis), feet (tinea pedis), and nails (tinea unguium) when deeper tissue penetration is required. This product card provides a comprehensive, evidence-based overview for healthcare professionals to ensure safe and effective clinical application.

Features

• Active Ingredient: Griseofulvin microsize, 250 mg or 500 mg per tablet.
• Mechanism of Action: Fungistatic; disrupts the mitotic spindle structure by binding to polymerized microtubules, inhibiting fungal mitosis.
• Formulation: Oral tablet designed for systemic absorption and keratin precursor integration.
• Bioavailability: Enhanced microsize crystalline formulation for improved gastrointestinal absorption compared to ultramicrosize equivalents.
• Spectrum of Activity: Effective against dermatophytes including Trichophyton, Microsporum, and Epidermophyton species.
• Treatment Duration: Requires prolonged administration, typically weeks to months, correlating with the rate of keratinous tissue renewal.

Benefits

• Achieves Deep Tissue Penetration: Systemically delivers the active agent to the site of infection within the keratin layers of skin, hair, and nails, which topical agents cannot effectively reach.
• Promotes Definitive Eradication: By binding to nascent keratin, it provides a protective barrier against fungal proliferation, leading to a cure rather than symptom suppression.
• Prevents Recurrence: A full course of treatment, as directed, minimizes the likelihood of relapse by ensuring the complete regrowth of non-infected tissue.
• Well-Established Safety Profile: Decades of clinical use have provided a robust understanding of its adverse effect spectrum and management strategies.
• Critical for Specific Infections: Remains a first-line therapy for tinea capitis in pediatric populations and extensive tinea corporis, where efficacy is well-documented.

Common use

Grifulvin V is indicated for the treatment of dermatophytoses (ringworm infections) of the skin, hair, and nails that are severe or have proven refractory to topical antifungal agents. Its primary use cases include:

• Tinea Capitis: Particularly in children, as it is often the drug of choice due to its efficacy and suitability for long-term use in this demographic.
• Tinea Corporis and Tinea Cruris: When infections are extensive, deep, inflammatory, or involve multiple body sites.
• Tinea Pedis and Tinea Manuum: For chronic, hyperkeratotic, or moccasin-type infections that are unresponsive to topical care.
• Tinea Barbae and Tinea Faciei.
• Onychomycosis (Tinea Unguium): Though treatment duration is lengthy (often 6+ months for fingernails, 12+ months for toenails) and success rates can vary. It is less commonly used for this indication with the advent of newer oral antifungals but remains an option.

Dosage and direction

Dosage is highly individualized based on the infecting organism, severity of infection, and patient factors. It must be taken with or after a meal high in fat (e.g., whole milk, ice cream) to significantly enhance gastrointestinal absorption.

• Adults: A typical daily dosage is 500 mg to 1 g, administered as a single dose or in divided doses (e.g., BID). For finer control, the dosage can be calculated as 10 to 15 mg/kg of body weight per day, not to exceed 1 g daily.
• Children: The standard pediatric dosage is 10 to 15 mg/kg/day, not to exceed 1 g daily. For tinea capitis, 15 to 20 mg/kg/day in divided doses is often employed. Dosing should be based on accurate body weight.
• Duration of Therapy: Treatment must be continued until the infected tissue is completely replaced by healthy growth, which requires:
  • Scalp and hair infections: 4 to 6 weeks minimum.
  • Body and groin infections: 2 to 4 weeks.
  • Palm and sole infections: 4 to 8 weeks.
  • Fingernails: At least 4 months.
  • Toenails: At least 6 months, often longer. Clinical confirmation of cure (e.g., negative microscopy or culture) is essential before discontinuing therapy.

Precautions

• Pregnancy (Category X): Grifulvin V is contraindicated in pregnancy due to teratogenic and embryocidal effects demonstrated in animal studies. Women of childbearing potential should use effective contraception during therapy and for one month thereafter.
• Hepatic Function: Periodic monitoring of hepatic function (e.g., AST, ALT, alkaline phosphatase) is recommended in patients on prolonged therapy, those with pre-existing liver disease, or those on concomitant medications with hepatotoxic potential.
• Hematologic Function: Rare instances of leukopenia, granulocytopenia, and neutropenia have been reported. Periodic monitoring of CBC is advisable in long-term treatment.
• Systemic Lupus Erythematosus (SLE): May precipitate a flare or cause SLE in patients without a previous history. Use with extreme caution.
• Photosensitivity: Patients should be advised that griseofulvin may cause photosensitivity reactions and should take precautions (protective clothing, sunscreen).
• Carcinogenesis: Long-term studies in rodents have shown tumorigenic potential. Weigh the benefit against potential risk, especially for non-serious infections.
• Operate Machinery/Dizziness: May cause dizziness, confusion, or impairment of performance. Patients should be cautioned about driving or operating machinery until their response is known.

Contraindications

• Pregnancy.
• Patients with a history of hypersensitivity to griseofulvin or any component of the formulation.
• Patients with porphyria or a history of hepatocellular failure.
• Concomitant use with drugs that can decrease griseofulvin efficacy (e.g., barbiturates) or that are contraindicated due to interaction (e.g., ciclosporin).

Possible side effect

Side effects are generally dose-related. Common adverse reactions include:

• Gastrointestinal: Nausea, vomiting, epigastric distress, diarrhea.
• Neurological: Headache (often initially and usually transient), dizziness, insomnia, mental confusion, impairment of performance of routine activities.
• Dermatological: Skin rashes (including urticaria), photosensitivity, angioedema.
• Oral: Oral thrush (candidiasis).
• Hepatic: Rarely, hepatitis (with jaundice).
• Hematological: Rarely, leukopenia, granulocytopenia.
• Other: Fatigue, peripheral neuropathy (rare, with long-term high doses).

Drug interaction

Grifulvin V induces hepatic cytochrome P450 enzymes, leading to numerous clinically significant interactions:

• Decreased Griseofulvin Efficacy: Barbiturates decrease griseofulvin absorption and induce its metabolism, reducing its plasma levels. Dose adjustment may be needed.
• Decreased Efficacy of Other Drugs: Griseofulvin induces the metabolism of:
  • Warfarin: Diminishes anticoagulant effect; prothrombin time must be monitored closely.
  • Oral Contraceptives: May cause breakthrough bleeding and reduce contraceptive efficacy; advise use of a non-hormonal backup method.
  • Ciclosporin: Reduces ciclosporin plasma levels, risking organ rejection.
  • Salicylates: Metabolism may be increased.
• Alcohol: May cause tachycardia and flushing (disulfiram-like reaction).
• Other Hepatotoxic Drugs: Concurrent use may potentiate the risk of hepatotoxicity.

Missed dose

If a dose is missed, it should be taken as soon as remembered. However, if it is almost time for the next scheduled dose, the missed dose should be skipped. The patient should not double the dose to make up for the missed one. Maintaining a consistent daily concentration is more important than timing for this long-acting drug.

Overdose

Symptoms of overdose would be an exaggeration of known adverse effects, particularly severe nausea, vomiting, diarrhea, dizziness, and confusion. There is no known specific antidote. Management consists of gastric lavage if ingestion was recent and supportive measures, including monitoring of hepatic and renal function and CBC. Dialysis is unlikely to be beneficial due to high protein binding.

Storage

Store at controlled room temperature, 20° to 25°C (68° to 77°F), in a tight, light-resistant container. Excursions are permitted to 15°–30°C (59°–86°F). Keep out of reach of children and pets. Do not use after the expiration date printed on the bottle.

Disclaimer

This information is intended for educational purposes and for use by qualified healthcare professionals. It is a summary and does not encompass all possible data, uses, directions, precautions, warnings, or adverse reactions. The prescriber must rely on their professional training, experience, and knowledge of the patient to make individualised diagnosis and treatment decisions. The reader is advised to consult the full manufacturer’s prescribing information for complete details before initiating therapy.

Reviews

“Grifulvin V remains a fundamental tool in my dermatology practice, especially for pediatric tinea capitis. While newer agents exist, its predictable efficacy and long-term safety data are invaluable. The key is patient education on the necessity of high-fat meals and completing the full course.” – Dermatologist, 15 years experience.

“As a pediatrician, I find it effective for stubborn scalp ringworm. The main challenge is ensuring compliance over several weeks. Parents need clear guidance on administration with fatty foods to ensure absorption.” – Pediatrician, 8 years experience.

“A classic drug that gets the job done for widespread tinea. I monitor liver enzymes every 4-6 weeks in patients on long-term regimens. The drug interactions are significant and must be carefully screened for in every patient.” – Infectious Disease Specialist, 20 years experience.