Telfin 1%30 ml

Terbinafine is an allylamine antifungal agent that works by inhibiting the biosynthesis of ergosterol, an essential component of the fungal cell membrane. It achieves this by blocking the enzyme squalene epoxidase, an early step in the ergosterol synthesis pathway.

This inhibition leads to fungal cell death primarily due to the accumulation of high intracellular concentrations of squalene, which increases cell membrane permeability, rather than from ergosterol deficiency alone. Depending on the drug concentration and the fungal species tested in vitro, terbinafine may be fungicidal (kills the fungus) rather than merely fungistatic (stops growth), though the clinical significance of in vitro data is not fully established.

Terbinafine has demonstrated activity, both in vitro and in clinical infections, against most strains of dermatophytes including Trichophyton mentagrophytes and Trichophyton rubrum. Because it targets an early and fungus-specific step of sterol synthesis, terbinafine has a favourable selectivity profile against fungal cells compared with human cells.

In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isoenzyme. Drugs that are predominantly metabolised by CYP450 2D6 may therefore have increased blood levels when taken with terbinafine. Affected drug classes include:

• Tricyclic antidepressants
• Selective serotonin reuptake inhibitors (SSRIs)
• Beta-blockers
• Class 1C antiarrhythmics (e.g. flecainide and propafenone)
• Monoamine oxidase inhibitors Type B (MAO-B inhibitors)

Co-administration of terbinafine with these medicines should be undertaken with careful clinical monitoring and may require a dose reduction of the 2D6-metabolised drug. Always inform your doctor about all prescription medicines, over-the-counter products and supplements you are taking.

The most commonly reported adverse events are generally mild, transient and rarely lead to discontinuation of treatment. These include:

• Gastrointestinal symptoms such as diarrhoea, dyspepsia (indigestion) and abdominal pain
• Liver test abnormalities
• Skin reactions including rashes, urticaria (hives) and pruritus (itching)
• Taste disturbances

Based on worldwide clinical experience, more serious but rarer adverse events have also been reported, including:

• Idiosyncratic and symptomatic hepatic (liver) injury, and rarely liver failure — some cases leading to death or liver transplant
• Serious skin reactions
• Severe neutropenia and thrombocytopenia (blood cell abnormalities)
• Angioedema and allergic reactions, including anaphylaxis
• Malaise, fatigue, vomiting, arthralgia (joint pain), myalgia (muscle pain) and hair loss

Seek medical attention promptly if you experience signs of liver problems (persistent nausea, dark urine, yellowing of the skin or eyes, upper abdominal pain), a progressive skin rash, or signs of a severe allergic reaction.

Terbinafine Tablet

There are no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of the human response, and because the treatment of onychomycosis can usually be postponed until after pregnancy, terbinafine tablets are not recommended during pregnancy. Terbinafine is excreted in breast milk after oral administration, so treatment is not recommended in nursing mothers.

Terbinafine Cream

Fetal toxicity and fertility studies in animals suggest no adverse effects. As there is no clinical experience in pregnant women, terbinafine cream should not be used during pregnancy unless the potential benefits clearly outweigh any potential risk. Since terbinafine is excreted in breast milk, mothers should not receive terbinafine treatment while breast-feeding.

Warnings

Terbinafine Tablets: Rare cases of liver failure — some leading to death or liver transplant — have occurred with the use of terbinafine tablets for onychomycosis, in individuals both with and without pre-existing liver disease. In most reported liver cases, patients had serious underlying systemic conditions with an uncertain causal association with terbinafine. The severity or outcome of hepatic events may be worse in patients with active or chronic liver disease. Treatment should be discontinued if there is biochemical or clinical evidence of liver injury.

There have been isolated reports of serious skin reactions such as Stevens-Johnson Syndrome and toxic epidermal necrolysis. If a progressive skin rash occurs, terbinafine should be discontinued.

Terbinafine Cream: For external use only. Avoid contact with the eyes.

Precautions

Telfin 1% 30 ml is not recommended for patients with chronic or active liver disease. Before prescribing, any pre-existing liver disease should be assessed, as hepatotoxicity may occur in patients with and without pre-existing liver disease. Pretreatment serum transaminase (ALT and AST) tests are advised for all patients before starting terbinafine tablets.

Clinical experience regarding overdose with terbinafine tablets is limited. Doses of up to 5 g (about 20 times the therapeutic daily dose) have been taken without inducing serious adverse reactions. Reported symptoms of overdose include nausea, vomiting, abdominal pain, dizziness, rash, frequent urination and headache. In case of a suspected overdose, seek medical assistance immediately.

Clinical experience regarding overdose with terbinafine tablets is limited. Doses of up to 5 g (about 20 times the therapeutic daily dose) have been taken without inducing serious adverse reactions. Reported symptoms of overdose include nausea, vomiting, abdominal pain, dizziness, rash, frequent urination and headache. In case of a suspected overdose, seek medical assistance immediately.

Pediatric Use

The safety and efficacy of terbinafine have not been established in pediatric patients, except where specifically indicated (e.g. oral granules for tinea capitis under medical supervision).

Use in the Elderly

There is no evidence to suggest that elderly patients require different dosages or experience side effects different from those of younger patients.