GRISEOFULVIN MICRO-SIZE

GRISEOFULVIN MICRO-SIZE
(gri-see-oh-ful'vin)
Fulvicin-U/F, Grifulvin V, Grisactin, Grisovin-FP

GRISEOFULVIN ULTRAMICROSIZE
Fulvicin P/G, Grisactin Ultra, Gris-PEG
Classifications: antibiotic; antifungal;
Therapeutic: antifungal antibiotic
Pregnancy Category: C

Availability

Griseofulvin Micro-Size: 250 mg, 500 mg tablets, 250 mg capsules; 125 mg/5 mL suspension

Griseofulvin Ultramicrosize: 125 mg, 165 mg, 250 mg, 330 mg tablets.

Action

Fungistatic antibiotic derived from species of Penicillium. Arrests metaphase of cell division by disrupting mitotic spindle structure in fungal cells. Deposits in keratin precursor cells and has special affinity for diseased tissue. It is tightly bound to new keratin of skin, hair, and nails, that becomes highly resistant to fungal invasion.

Therapeutic Effect

Effective against various species of Epidermophyton, Microsporum, and Trichophyton (has no effect on other fungi, including Candida, bacteria, and yeasts).

Uses

Mycotic disease of skin, hair, and nails not amenable to conventional topical measures. Concomitant use of appropriate topical agent may be required, particularly for tinea pedis.

Unlabeled Uses

Raynaud's disease, angina pectoris, and gout.

Contraindications

SLE; pregnancy (category C), lactation, children ≤2 y, prophylaxis against fungal infections.

Cautious Use

Penicillin-sensitive patients (possibility if cross-sensitivity with penicillin exists; however, reportedly penicillin-sensitive patients have been treated without difficulty); porphyria; hepatic disease.

Route & Dosage

Tinea Corporis, Tinea Cruris, Tinea Capitis
Adult: PO 500 mg micro-size or 330–375 mg ultramicrosize daily in single or divided doses
Child: PO 10–20 mg/kg/d micro-size or 5–10 mg/kg/d ultramicrosize in single or divided doses

Tinea Pedis, Tinea Unguium
Adult: PO 0.75–1 g micro-size or 660–750 mg ultramicrosize daily in single or divided doses (decrease micro-size dose to 500 mg/d after response is noted)
Child: PO 10–20 mg/kg/d micro-size or 5–10 mg/kg/d ultramicrosize in single or divided doses

Administration

Oral

Give with or after meals to allay GI disturbances.
Give the micro-size formulations with a high fat content meal (increases drug absorption rate) to enhance serum levels. Consult physician.
Store at 15°–30° C (59°–86° F) in tightly covered containers unless otherwise directed.

Adverse Effects (≥1%)

Body as a Whole: Hypersensitivity (urticaria, photosensitivity, skin rashes, pruritus, fixed drug eruption, serum sickness syndromes, severe angioedema). CNS: Severe headache, insomnia, fatigue, mental confusion, impaired performance of routine functions, psychotic symptoms, vertigo. GI: Heartburn, nausea, vomiting, diarrhea, flatulence, dry mouth, thirst, decreased taste acuity, anorexia, unpleasant taste, furred tongue, oral thrush. Hematologic: Leukopenia, neutropenia, granulocytopenia, punctate basophilia, monocytosis. Urogenital: Nephrotoxicity (proteinuria); hepatotoxicity; estrogen-like effects (in children); aggravation of SLE. Other: Overgrowth of nonsusceptible organisms; candidal intertrigo.

Interactions

Drug: Alcohol may cause flushing and tachycardia; barbiturates may decrease activity of griseofulvin; may decrease hypoprothrombinemic effects of oral anticoagulants; may increase estrogen metabolism, resulting in break through bleeding, and decrease contraceptive efficacy of oral contraceptives.

Pharmacokinetics

Absorption: Absorbed primarily from duodenum; micro-size is variably and unpredictably absorbed; ultramicrosize is almost completely absorbed. Peak: 4–8 h. Distribution: Concentrates in skin, hair, nails, fat, and skeletal muscle; crosses placenta. Metabolism: In liver. Elimination: Mainly in urine; some excretion in perspiration. Half-Life: 9–24 h.

Nursing Implications

Assessment & Drug Effects

Inquire about history of sensitivity to griseofulvin, penicillins, or other allergies prior to initiating treatment.
Monitor food intake. Drug may alter taste sensations, and this may cause appetite suppression and inadequate nutrient intake.
Lab tests: WBC with differential at least once weekly during first month of therapy or longer; periodic renal and hepatic function tests are also advised.
Continue treatment until there is clinical improvement or until 2 or 3 consecutive weekly cultures are negative.

Patient & Family Education

Continuing treatment as prescribed to prevent relapse, even if you experience symptomatic relief after 48–96 h of therapy.
Note: Duration of treatment depends on time required to replace infected skin, hair, or nails, and thus varies with infection site. Average duration of treatment for tinea capitis (scalp ringworm), 4–6 wk; tinea corporis (body ringworm), 2–4 wk; tinea pedis (athlete's foot), 4–8 wk; tinea unguium (nail fungus), at least 4 mo for fingernails, depending on rate of growth, and 6 mo or more for toenails.
Avoid exposure to intense natural or artificial sunlight, because photosensitivity-type reactions may occur.
Note: Headaches often occur during early therapy but frequently disappear with continued drug administration.
Disulfiram-type reaction (see Appendix F) are possible with ingestion of alcohol during therapy.
Pharmacologic effects of oral contraceptives may be reduced. Breakthrough bleeding and pregnancy may occur. Alternative forms of birth control should be used during therapy.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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