GRISEOFULVIN Film-coated tablets Ref.[8522] Active ingredients: Griseofulvin

Griseofulvin is reccomended after a high fat meal for increased absorption and minimising GI distress.

Griseofulvin is contraindicated in patients with severe hepatic impairment, see section 4.3. In patients with minor to moderate hepatic impairment, griseofulvin may cause further deterioration of hepatic function. Therefore care should be exercised with such patients, and it is recommended to perform regular periodic liver function tests, see section 4.8.

Griseofulvin is contraindicated in patients with Systemic Lupus Erythematosus (SLE), see section 4.3; griseofulvin has been reported to exacerbate the conditions, and care should be taken to exclude patients with pre-existing SLE from therapy.

Animal data, see section 5.3, indicates long term administration of high dose griseofulvin induces tumours in some species, but not others. The clinical relevance of this to man is unknown, but griseofulvin should not be used prophylactically.

Griseofulvin is a liver microsomal enzyme inducer and thus may impair the effectiveness of oral contraceptives. Therefore in women of child bearing age using oral contraception, additional barrier methods of contraception must be used during therapy and for 4 weeks following therapy cessation, see sections 4.5 and 4.6.

Griseofulvin causes chromosomal abnormalities in animals, see section 5.3. Therefore sexually active males should be cautioned to use an effective barrier method of contraception throughout therapy and for 6 months after therapy termination, see section 4.6.

A theoretical possibility of cross sensitivity in patients known to be allergic to penicillins exists, therefore caution should be exercised in administration of griseofulvin to such patients. It should be noted that such patients have been satisfactorily treated with griseofulvin without sequelae.

Patients should be cautioned to avoid excessive and unnecessary exposure to sunlight or U.V sources, including sunbeds, during griseofulvin therapy as photosensitivity reactions can occur, see section 4.8.

Consumption of alcohol in association with griseofulvin can result in an “Antabuse” type reaction, see section 4.5. Patients should be cautioned to avoid consumption of alcoholic beverages, and medicines containing alcohol, while undergoing griseofulvin therapy.

In patients undergoing long term griseofulvin therapy, i.e for tinea unguium, consideration should be given to periodic monitoring of blood chemistry, particularly for patients with pre-existing blood disorders, since griseofulvin may cause blood disorders, see section 4.8.

In common with any antibiotic, therapy with griseofulvin may result in the overgrowth of non-susceptible organisms, i.e bacteria or yeasts, or non-dermatophyte fungi, that are often cofactors in tinea infections, especially tinea pedis. Additional therapy is required to control or eradicate such organisms, as griseofulvin is ineffective.

Griseofulvin is not effective in infections due to Candida albicans, Aspergillus sp., MMalassezia furfur (Pittyriasis versiclor) and Nocardia sp. It has no antibacterial effects.

Medicinal Products

Griseofulvin may depress plasma levels, and therefore the efficacy, of concommitantly administered medicinal products that are metabolised by cytochrome P450 3A4.

Interactions of Griseofulvin with other drugs

Ciclosporin: concomittant administration may result in a reduction of ciclosporin plasma levels, necessitating a dosage adjustment. Plasma levels of ciclosporin should be monitored during grisefulvin therapy, and necessary dosage adjustments made.

Coumarin anticoagulants: the efficacy may be reduced, necessitating dosage adjustment. It is recommended that both prothrombin and INR are regularly monitored, for the duration of griseofulvin therapy, and for 8 days post therapy cessation.

Methadone: depression of methadone plasma levels may occur during griseofulvin therapy. Patients should be closely monitored for any loss of efficacy, or plasma levels of methadone be monitored, and corresponding dosage adjustments made.

Oral contraceptives: efficacy of oral contraception is reduced during griseofulvin therapy and for four weeks post therapy cessation. In view of the contraindication in pregnancy, see section 4.3, and of the possible sequelae of male patients fathering a child during therapy, all sexually active patients should use additional barrier contraception, such as condoms, throughout griseofulvin therapy, and for four weeks (female) and 6 months (male) post therapy cessation. See also sections 4.3, 4.4, 4.6, and 5.3 for additional information.

Interactions of other drugs with griseofulvin

Concurrent administration of other medicinal products that induce metabolising enzymes may result in a reduction of griseofulvin blood plasma levels and thus efficacy. The following drugs are known to have this effect:

Barbiturates, such as phenobarbitone
Doxercalciferol
Phenylbutazone
Primidone

Other sedative and hypnotic drugs that induce metabolising enzymes.

Food: administration of griseofulvin after food, results in increased absorption, and thus higher plasma levels. This effect is enhanced if the meal contains high fat content. Administration after food is recommended, see section 4.2.

Alcohol: there are reports that griseofulvin enhances the central nervous system effects of alcohol. There are also reports that griseofulvin and alcohol use result in an “Antabuse” type reaction. Patients should be cautioned to avoid alcohol and all alcohol containing products while undergoing griseofulvin therapy, See also section 4.8.

Pregnancy

There are case reports of human foetal abnormalities associated with griseofulvin.

There are no adequate and well controlled studies in man, and inadequate epidemiological data. Griseofulvin has been shown to be teratogenic and embryotoxic in mice and rats. (see section 5.3).

Griseofulvin is suspected to cause serious birth defects when administered during pregnancy.

Griseofulvin is contraindicated (see section 4.3) in pregnancy.

Women of childbearing potential have to use effective contraception during (and up to 4 weeks after) treatment (see section 4.5) in respect of effect on oral contraceptives, and contraceptive precautions.

Male-mediated effects on pregnancy

Griseofulvin has been shown to induce chromosomal aberrations in animal spermatocytes (see section 5.3). Therefore men should take effective contraceptive precautions, i.e barrier contraception, to avoid fathering children for the duration of griseofulvin therapy, and for 6 months post therapy cessation.

Lactation

It is unknown if griseofulvin is excreted in breast milk, but the possibility does exist. There is inadequate data on the safety of griseofulvin in breast feeding, and the potential risk to the infant cannot be assessed, therefore griseofulvin is contraindicated in breast feeding (see section 4.3).

Griseofulvin has no or negligible influence on the ability to drive and use machines. However, it may cause drowsiness, confusion dizziness, and impaired co-ordination, see section 4.8. Patients should therefore be cautioned not to drive or operate machines until they are sure they are not affected.

The following frequencies are used for the description of the occurrence of undesirable effects:

Very common: ≥1/10
Common: ≥1/100, <1/10
Uncommon: ≥1/1,000, <1/100
Rare: ≥1/10,000, <1/1,000
Very rare: <1/10,000

Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness.

Headache and gastric discomfort are the most common effects on starting treatment, but usually disappear as treatment is continued.

Blood and lymphatic system disorder

Rare: leucopenia, neutropenia, anaemia-these usually resolve on therapy cessation

Nervous system disorders

Common: headache

Uncommon: impaired co-ordination, peripheral neuropathy, confusion, dizziness, drowsiness, insomnia, irritability.

Gastrointestinal disorders

Common: diarrhoea, vomiting, nausea, gastric discomfort

Uncommon: anorexia, taste sensation changes

Skin and subcutaneous tissue disorders

Uncommon: toxic epidermal necrolysis, erethema multiforme, photosensitivity on exposure to intense natural or artifical sunlight.

Rare: precipitation of Systemic Lupus Eryhthematosus, bullous reactions including Lyell’s syndrome, urticarial reactions, skin rashes.

Hepatobiliary disorders

Very rare: alteration in liver function tests, with elevation to more than three times upper normal limit, intrahepatic cholecstasis, hepatitis.

Not applicable.