griseofulvin (Gris-Peg, Grifulvin V, Griseofulvin Ultramicrosize) (cont.)

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  • Oral suspension (microsize): 125 mg/5ml
  • Microsize: Oral tablets: 250 mg, 500 mg
  • Ultramicrosize oral tablets: 125 mg, 250 mg,

STORAGE: Griseofulvin should be stored at room temperature, between 15 C and 30 C (59 F and 86 F).



  • The recommended dose is 375 mg daily or 250 mg three times daily of the ultramicrosize formulation depending on the type of infection. 
  • The dosing recommendation for the microsize formulation is 500 mg once or twice daily, or 1000 mg as a single dose depending on the type of fungal infection.

The duration of treatment varies and is generally continued until the fungal infection is completed eradicated. It is usually taken for

  • 2 to 4 weeks for skin infections,
  • 4 to 6 weeks for hair and scalp infections,
  • 4 to 8 weeks for foot infections,
  • 3 to 4 months for fingernail infections, and
  • a minimum of at least 6 months for toenail infections.

DRUG INTERACTIONS: Griseofulvin interacts with many drugs. Patients should consult the prescribing information for a complete list of drugs that interact with griseofulvin. Known drug interactions include:

  • Griseofulvin increases the activity of CYP3A4 liver enzymes. Griseofulvin should not be combined with other drugs that are metabolized (broken down) by CYP3A4 enzymes because griseofulvin may decrease their blood concentrations, decreasing treatment effectiveness. Examples of drugs metabolized by CYP3A4 enzymes include atazanavir (Reyataz), bedaquiline (Sirturo), daclatasvir (Daklinza), darunavir (Prezista), gefitinib (Iressa), nilotinib (Tasigna), palbociclib (Ibrance), telithromycin (Ketek), and several other drugs.
  • Use of griseofulvin with birth control pills may reduce the effectiveness of birth control pills and cause breakthrough bleeding. Patients should use an alternative or additional form of birth control (contraception) while on griseofulvin therapy and for up to 1 month after stopping treatment.
  • The effectiveness of warfarin (Coumadin, Jantoven) may be reduced by griseofulvin because griseofulvin may increase the breakdown warfarin by enzymes in the liver.
Medically Reviewed by a Doctor on 10/14/2015

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