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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Fulvicin P/g 165
Generic Name
Ultramicrosize Griseofulvin
Active Ingredient
GriseofulvinCategory
Tubulin Inhibiting Agent [EPC]
Variants
1
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 165 mg/1 | TABLET | ORAL | 69499-435 |
Detailed information about Fulvicin P/g 165
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Fulvicin P/g 165, you must consult a qualified healthcare professional.
Griseofulvin is a potent antifungal medication belonging to the tubulin inhibiting agent class, primarily used to treat skin, hair, and nail infections caused by dermatophytes.
The dosage of Griseofulvin depends heavily on the type of infection being treated and the formulation (microsize vs. ultramicrosize) prescribed by your healthcare provider.
Griseofulvin is frequently used in children, particularly for tinea capitis. Dosage is calculated based on the child's weight.
Because Griseofulvin is primarily metabolized by the liver, significant dose adjustments are rarely required for patients with mild to moderate kidney disease. However, caution is advised in severe renal failure.
Griseofulvin is contraindicated (should not be used) in patients with hepatocellular failure (severe liver disease). In patients with mild liver impairment, healthcare providers will monitor liver function tests (LFTs) closely.
Clinical studies did not include sufficient numbers of subjects aged 65 and over to determine if they respond differently than younger subjects. In general, dose selection for an elderly patient should be cautious, starting at the low end of the dosing range due to the higher frequency of decreased hepatic or renal function.
To ensure the medication works effectively, follow these specific instructions:
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and return to your regular schedule. Do not double the dose to catch up.
Symptoms of a Griseofulvin overdose are generally rare but may include lethargy, confusion, or severe GI distress. If an overdose is suspected, contact a Poison Control Center or seek emergency medical attention immediately. Treatment is supportive and may include gastric lavage (stomach pumping) if performed shortly after ingestion.
> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose without medical guidance. Long-term therapy requires periodic monitoring of blood, liver, and kidney functions.
Griseofulvin is generally well-tolerated, but some side effects are common, especially during the first few weeks of treatment:
> Warning: Stop taking Griseofulvin and call your doctor immediately if you experience any of these serious symptoms:
With prolonged use (often necessary for nail infections), there is an increased risk for organ toxicity. Animal studies have shown that Griseofulvin may have carcinogenic (cancer-causing) and mutagenic (DNA-damaging) potential. While these effects have not been definitively proven in humans, healthcare providers limit the duration of therapy to the minimum necessary to clear the infection. Long-term use also necessitates regular blood work to monitor the liver and bone marrow.
No FDA black box warnings for Griseofulvin. However, it carries significant warnings regarding its use during pregnancy and its potential for liver toxicity. The FDA-approved label emphasizes that Griseofulvin should not be used in pregnant women due to reports of fetal abnormalities and conjoined twins.
Report any unusual symptoms to your healthcare provider. Early detection of side effects is key to preventing long-term complications.
Griseofulvin is a powerful systemic medication that requires careful medical supervision. It is not a first-line treatment for minor skin infections that can be managed with topical creams. Patients must be aware that this drug affects cell division and can interact with various biological processes beyond the fungal infection.
No FDA black box warnings for Griseofulvin. However, the FDA-approved labeling includes a Category X pregnancy warning, which is the highest level of warning regarding fetal risk.
Because Griseofulvin is often taken for long periods, regular monitoring is essential:
Griseofulvin may cause dizziness, confusion, or impaired coordination in some individuals. You should not drive or operate heavy machinery until you know how the medication affects you. If you experience significant dizziness or mental clouding, contact your doctor.
Alcohol should be avoided or used with extreme caution while taking Griseofulvin. The drug can potentiate (increase) the effects of alcohol, leading to rapid heart rate, flushing, and nausea (a disulfiram-like reaction). Furthermore, both alcohol and Griseofulvin stress the liver, increasing the risk of hepatotoxicity.
There is no specific withdrawal syndrome associated with Griseofulvin, and tapering is generally not required. However, the most significant risk of discontinuation is the return of the fungal infection. If the medication is stopped before the fungus is completely cleared from the keratinized tissue, the infection will likely recur. Always complete the full course as prescribed by your doctor.
> Important: Discuss all your medical conditions with your healthcare provider before starting Griseofulvin. Be sure to mention if you have a history of liver disease, kidney disease, or lupus.
While few drugs are strictly contraindicated, the use of Griseofulvin with certain substances is highly discouraged due to severe risks:
Griseofulvin is a potent inducer of the CYP450 enzyme system, particularly the 3A4 isoenzyme. This means it speeds up the metabolism of other drugs, making them less effective.
Griseofulvin can interfere with certain laboratory tests:
For each major interaction, the mechanism is typically enzyme induction, where Griseofulvin stimulates the liver to break down other drugs faster than normal. This results in reduced efficacy of the co-administered drug. Management involves dose adjustments of the affected drug and close clinical monitoring.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. Do not start any new medication without consulting your healthcare provider while on Griseofulvin.
Griseofulvin must NEVER be used in patients with the following conditions:
Healthcare providers will perform a careful risk-benefit analysis in the following scenarios:
There is a potential for cross-sensitivity between Griseofulvin and other Penicillium-derived products. If a patient has experienced a severe allergic reaction (like hives, swelling, or difficulty breathing) to any mold-derived product, they should inform their doctor before starting Griseofulvin.
> Important: Your healthcare provider will evaluate your complete medical history, including any history of liver disease or autoimmune conditions, before prescribing Griseofulvin.
Griseofulvin is strictly contraindicated during pregnancy (Category X). There is documented evidence of human fetal risk based on adverse reaction reports and animal studies. Specifically, reports have linked Griseofulvin use during the first trimester to the birth of conjoined twins and other structural abnormalities. Women of childbearing age must use effective, non-hormonal contraception during therapy. If pregnancy occurs while taking this drug, the patient must be apprised of the potential hazard to the fetus.
It is not known whether Griseofulvin is excreted in human breast milk. Because of the potential for serious adverse reactions in nursing infants (including potential carcinogenicity observed in animal studies), a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. Most healthcare providers recommend avoiding breastfeeding while on systemic Griseofulvin.
Griseofulvin is a standard treatment for tinea capitis in children. However, its safety in children under 2 years of age has not been established. In older children, the drug is generally well-tolerated, but the liquid suspension (microsize) is preferred for accurate weight-based dosing. Healthcare providers should monitor blood counts in children receiving long-term therapy, as leukopenia has been reported.
Elderly patients are at a higher risk for hepatic and renal impairment. Since Griseofulvin is metabolized by the liver, the risk of toxicity is higher in this population. Furthermore, elderly patients are often on multiple medications (polypharmacy), increasing the risk of significant drug interactions with CYP450-inducing Griseofulvin. Doctors typically start with the lowest effective dose and monitor liver function closely.
While the kidneys are not the primary route of Griseofulvin metabolism, the drug's safety in severe renal impairment has not been extensively studied. For patients with a GFR (Glomerular Filtration Rate) below 30 mL/min, healthcare providers may monitor for protein in the urine (proteinuria) and adjust therapy if kidney function declines.
Griseofulvin is contraindicated in hepatocellular failure. In patients with mild to moderate hepatic impairment (Child-Pugh Class A or B), the drug should be used with extreme caution. Liver enzyme elevations (ALT, AST) are common and may require discontinuation of the drug if they exceed three times the upper limit of normal.
> Important: Special populations require individualized medical assessment. Always disclose your full health history and any plans for pregnancy to your prescribing physician.
Griseofulvin is a Tubulin Inhibiting Agent. Its primary molecular target is the fungal tubulin protein. By binding to tubulin, it inhibits the assembly of microtubules, which are critical components of the mitotic spindle. Without a functional mitotic spindle, the fungal cell cannot move its chromosomes during cell division, leading to an arrest in metaphase. This effectively stops the growth and replication of the fungus (fungistatic effect). Griseofulvin also disrupts other microtubule-dependent processes, such as the transport of cellular components and the maintenance of cell shape. Its high affinity for keratin ensures that it is concentrated exactly where the dermatophytes reside.
The antifungal effect of Griseofulvin is time-dependent. Because it only works on actively dividing cells and must be incorporated into new keratin, the clinical response is slow. It has no effect on bacteria or other types of fungi (like yeasts) because their tubulin structures or transport mechanisms differ. Tolerance to Griseofulvin is rare, but treatment failure is common if the drug is not taken with fat or if the course is not completed.
| Parameter | Value |
|---|---|
| Bioavailability | Variable (Highly increased with fatty meals) |
| Protein Binding | Approximately 80% (primarily to albumin) |
| Half-life | 9 to 24 hours |
| Tmax | 4 hours (highly variable) |
| Metabolism | Hepatic (6-demethylgriseofulvin) |
| Excretion | Renal (30%), Fecal (significant portion of unabsorbed drug) |
Griseofulvin is the sole member of its specific chemical class used systemically. While it shares the "Tubulin Inhibiting" mechanism with certain chemotherapy drugs (like vincristine) and anti-gout medications (like colchicine), its specificity for fungal tubulin makes it a unique antifungal agent. It is distinct from the azoles (which inhibit ergosterol synthesis) and the allylamines (which inhibit squalene epoxidase).
Common questions about Fulvicin P/g 165
Griseofulvin is an oral antifungal medication used to treat fungal infections of the skin, hair, and nails, such as ringworm, athlete's foot, and jock itch. It is specifically effective against a group of fungi called dermatophytes, which require keratin to grow. Healthcare providers often prescribe it when topical creams or ointments have failed to clear the infection. It is particularly common in treating tinea capitis, which is a fungal infection of the scalp that affects the hair shafts. Because it works by being incorporated into new skin and hair, it is a long-term treatment rather than a quick fix.
The most frequently reported side effect of Griseofulvin is a headache, which can sometimes be severe but often disappears as treatment continues. Many patients also experience gastrointestinal issues, such as nausea, vomiting, diarrhea, or an upset stomach. Some individuals may develop oral thrush, characterized by white patches in the mouth, due to changes in the body's natural flora. Skin rashes and increased sensitivity to sunlight (photosensitivity) are also relatively common. Most of these side effects are mild, but you should always report persistent or worsening symptoms to your doctor.
It is strongly recommended that you avoid alcohol while taking Griseofulvin. The medication can cause a disulfiram-like reaction when combined with alcohol, leading to unpleasant symptoms such as flushing, a rapid heartbeat, nausea, and sweating. Additionally, both Griseofulvin and alcohol are processed by the liver, and combining them can increase the risk of liver irritation or damage. Even small amounts of alcohol can trigger these effects in sensitive individuals. To ensure your safety and the effectiveness of the medication, it is best to abstain from alcohol until the treatment is finished.
No, Griseofulvin is not safe for use during pregnancy and is classified as FDA Pregnancy Category X. It has been linked to serious birth defects, including reports of conjoined twins and other fetal abnormalities. Women of childbearing age must use effective, non-hormonal birth control during treatment and for at least one month after the final dose. Men should also avoid fathering a child for at least six months after stopping the medication, as it may affect sperm. If you become pregnant while taking Griseofulvin, you must contact your healthcare provider immediately.
Griseofulvin works slowly because it must be absorbed into the new keratin being formed in your skin, hair, or nails. For skin infections like ringworm, you may need to take it for 2 to 4 weeks. Scalp infections typically require 4 to 6 weeks of consistent treatment to ensure the fungus is cleared from the hair follicles. Nail infections are the slowest to heal, often requiring 3 to 6 months of therapy or until the infected nail has completely grown out and been replaced. Consistency is key, and you should continue taking the medication for the full duration prescribed.
While you can technically stop taking Griseofulvin without experiencing withdrawal symptoms, doing so before the infection is fully cleared is highly discouraged. If you stop the medication early, the fungus that remains in the deeper layers of your skin or nails can begin to grow again, leading to a relapse. This recurrent infection may be more difficult to treat the second time around. Always finish the entire course of medication as directed by your healthcare provider, even if your symptoms seem to have disappeared. If you need to stop due to side effects, consult your doctor for an alternative.
If you miss a dose of Griseofulvin, take it as soon as you remember, ideally with a meal containing some fat. However, if it is nearly time for your next scheduled dose, skip the missed one and continue with your regular dosing schedule. Do not take two doses at once to make up for the missed one, as this can increase the risk of side effects like severe headache or stomach upset. To help remember your doses, try taking the medication at the same time each day, such as with dinner. Consistent levels of the drug in your system are important for fighting the fungus effectively.
Weight gain is not a commonly reported side effect of Griseofulvin in clinical trials or FDA labeling. Most side effects related to metabolism or the digestive system involve weight loss or decreased appetite due to nausea and stomach upset. If you notice significant or rapid weight gain while taking this medication, it may be due to other factors or a rare reaction like fluid retention. You should discuss any unexpected changes in your weight with your healthcare provider. It is also important to remember that the high-fat meals required for drug absorption should be balanced within your overall diet.
Griseofulvin has several significant drug interactions because it speeds up the metabolism of other medications in the liver. It can make birth control pills less effective, increasing the risk of pregnancy, and can reduce the effectiveness of blood thinners like warfarin. It may also interact with barbiturates and certain organ transplant medications like cyclosporine. Because of these risks, it is vital to provide your doctor with a complete list of all prescription drugs, over-the-counter medicines, and herbal supplements you are taking. Your doctor may need to adjust your dosages or monitor you more closely during treatment.
Yes, Griseofulvin is available as a generic medication in both microsize and ultramicrosize formulations. Generic versions are typically more cost-effective than brand-name versions and are required by the FDA to have the same active ingredient, strength, and efficacy. You may find it under the generic name Griseofulvin or older brand names like Grifulvin V or Gris-PEG. When filling your prescription, ensure you receive the specific formulation (microsize vs. ultramicrosize) that your doctor prescribed, as the doses are not interchangeable. Check with your pharmacist if you have questions about the specific generic version you are dispensed.
Other drugs with the same active ingredient (Griseofulvin)