Indications

Terbinafine tablet: This tablet is used to treat dermatophytes-caused onychomycosis of the toenail or fingernail (tinea unguium).

Trichophyton (e.g. T. rubrum, T. mentagrophytes, T. verrucosum, T. violaceus), Microsporum canis, and Epidermophyton floccosum cause fungal infections of the skin. Yeast infections of the skin, are mostly caused by the Candida genus (e.g. C. albicans). Due to Pityrosporum orbiculare, pityriasis (tinea) versicolor develops (also known as Malassezia furfur).

Pharmacology

Terbinafine, an antifungal Allylamine, inhibits the production of Ergosterol (an important component of fungi cell membranes) by inhibiting the Squalene Epoxidase enzyme. This causes fungal cell death largely owing to increased membrane permeability caused by high levels of Squalene buildup, rather than Ergosterol insufficiency. Terbinafine hydrochloride may be fungicidal depending on the medication concentration and the fungus species tested in vitro. The clinical relevance of in vitro findings, on the other hand, remains uncertain.

Dosage & Administration

Terbinafine tablet:

• For the treatment of fingernail onychomycosis: Terbinafine 250 mg (one tablet), once daily for 6 weeks.
• For the treatment of toenail onychomycosis: Terbinafine 250 mg (one tablet), once daily for 12 weeks.
• The optimal clinical effect is seen some months after mycological cure and cessation of treatment. This is related to the period required for the outgrowth of healthy nails.

Terbinafine cream: Terbinafine cream can be applied once or twice daily. Cleanse and dry the affected areas thoroughly before the application of the terbinafine cream. Apply the cream to the affected skin and the surrounding area in a thin layer and rub it lightly. In the case of intertriginous infections (submammary, interdigital, intergluteal, inguinal) the application may be covered with a gauze strip, especially at night. The likely durations of treatment are as follows:

• Tinea corporis, cruris: 1 to 2 weeks
• Tinea pedis: 1 week
• Cutaneous candidiasis: 2 weeks
• Pityriasis Versicolor: 2 weeks

Relief of the clinical symptoms usually occurs within a few days. Irregular use or premature discontinuation of treatment carries the risk of recurrence. If there are no signs of improvement after two weeks, the diagnosis should be verified.

Interaction

Terbinafine inhibits the CYP450 2D6 isozyme in vivo, according to research. Tricyclic antidepressants, selective serotonin reuptake inhibitors, beta-blockers, antiarrhythmics class 1C (e.g., flecainide and propafenone), and monoamine oxidase inhibitors Type B are among the drugs processed mostly by the CYP450 2D6 isozyme. Co-administration of terbinafine should be done with caution, and the dose of the 2D6-metabolized medication may need to be reduced.

Contraindications

Terbinafine tablets and cream are not recommended for people who are hypersensitive to terbinafine.

Side Effect

Gastrointestinal symptoms (including diarrhea, dyspepsia, and stomach discomfort), liver test abnormalities, rashes, urticaria, itching, and taste changes are among the side effects described. In general, the side effects were minor and transitory, and they did not necessitate stopping the medication. Idiosyncratic and symptomatic hepatic damage, and more infrequently, instances of liver failure, some resulting in death or liver transplant, significant skin responses, severe neutropenia, thrombocytopenia, angioedema, and allergic reactions, according to international experience with terbinafine usage (including anaphylaxis).

Pregnancy & Lactation

Terbinafine tablet: No appropriate and well-controlled trials in pregnant women have been conducted. Terbinafine should not be started during pregnancy since animal reproduction studies are not necessarily predictive of human response, and onychomycosis therapy can be postponed until after the pregnancy has finished. Terbinafine is found in the breast milk of nursing women after oral dosing. Terbinafine is not advised for use in breastfeeding mothers.

Terbinafine cream has been shown to have no negative effects on fetal toxicity and fertility in animals. There is no clinical experience with terbinafine in pregnant women; thus, terbinafine should not be used unless the possible benefits outweigh the potential risks. Terbinafine is secreted in breast milk, thus women who are breastfeeding should avoid terbinafine therapy.

Precautions & Warnings

Terbinafine pills: The use of terbinafine tablets for the treatment of onychomycosis in persons with and without preexisting liver disease has resulted in rare occurrences of liver failure, some of which have resulted in death or liver transplantation. Patients with significant underlying systemic illnesses and an unclear causal relationship with terbinafine were seen in the majority of liver cases reported in conjunction with terbinafine usage. In individuals with current or chronic liver disease, the severity of hepatic events and/or their prognosis may be worse. If you have biochemical or clinical signs of liver damage, you should stop using terbinafine pills.

Terbinafine is not advised for people with active or chronic liver disease. Pre-existing liver disease should be evaluated before Terbinafine is prescribed. Hepatotoxicity can affect people with or without a history of liver disease. Before using terbinafine pills, all patients should have their serum transaminase (ALT and AST) levels tested.

Therapeutic Class

Drugs for subcutaneous and mycoses, Topical Antifungal preparations

Storage Conditions

Store in a cool and dry place, below 30°C, and protect from light.

Generic

Terbinafine Hydrochloride

Pharmaceutical Name

General Pharmaceuticals Ltd.