Terfix250 mg

Oral Tablet – Onychomycosis (Fungal Nail Infection)

Terfix 250 mg oral tablets are indicated for the treatment of onychomycosis (fungal infection) of the toenail or fingernail caused by dermatophytes (tinea unguium). This is an established, regulatory-approved indication. Appropriate nail specimens should be tested to confirm the fungal diagnosis before Terfix is started, since oral therapy is reserved for confirmed dermatophyte nail infections.

Topical Cream / Gel / Spray – Tinea Pedis, Tinea Cruris, and Tinea Corporis

Terfix 1% topical cream, gel, and spray are indicated for the treatment of tinea pedis (athlete's foot), tinea cruris (jock itch), and tinea corporis (ringworm) caused by susceptible dermatophytes. This is an established indication supported by the regulatory labeling of topical Terfix products.

Topical Cream / Gel – Cutaneous Candidiasis and Pityriasis Versicolor

Topical Terfix 1% cream/gel is also used for cutaneous candidiasis and pityriasis versicolor (tinea versicolor), per product labeling of Terfix marketed in Bangladesh. This use is guideline-supported for these specific yeast infections; the exact regimen and expected response can differ from dermatophyte skin infections, so it should be confirmed by a qualified healthcare professional.

Each formulation contains the active ingredient Terbinafine Hydrochloride as follows:

• Oral Tablet: Terbinafine Hydrochloride 250 mg per tablet.
• Topical Cream/Gel: Terbinafine Hydrochloride 1% w/w.
• Topical Spray: Terbinafine Hydrochloride 1% w/v.

Terfix is an antifungal medicine that belongs to the allylamine class and is used to treat fungal infections of the nails and skin. In Bangladesh, Terfix is available as a 250 mg oral tablet for fungal nail infections (onychomycosis) and as a 1% topical cream, gel, or spray for common skin fungal infections such as athlete's foot, jock itch, and ringworm. Terfix works by stopping fungi from building an essential component of their cell membrane, which leads to fungal cell death. The oral tablet is absorbed into the bloodstream and requires medical supervision because of rare but serious effects on the liver, while the topical forms of Terfix act mainly on the skin surface with only minimal absorption into the body. Because the correct formulation, dose, and treatment duration depend on the type and severity of infection, Terfix should always be used under the guidance of a qualified healthcare professional.

Antifungal (Allylamine)

Terbinafine Hydrochloride is a synthetic allylamine antifungal. It acts by inhibiting the fungal enzyme squalene epoxidase, blocking an early step in ergosterol biosynthesis. This causes squalene to accumulate within the fungal cell and results in fungal cell death, so Terbinafine Hydrochloride is considered fungicidal against common dermatophytes such as Trichophyton species, depending on concentration and organism.

After oral dosing, Terbinafine Hydrochloride is well absorbed (over 70%) but undergoes significant first-pass hepatic metabolism, giving an absolute bioavailability of about 40%. It is more than 99% bound to plasma proteins, is extensively metabolized by multiple CYP450 enzymes (with a notable inhibitory effect on CYP2D6), and is eliminated mainly in the urine; its effective half-life is roughly 36 hours at steady state, with a much longer terminal half-life reflecting slow release from fat and skin tissue. Terbinafine Hydrochloride concentrates in skin, hair, and nails, which supports its efficacy in cutaneous and nail infections.

When Terbinafine Hydrochloride is applied topically as a cream, gel, or spray, systemic absorption through intact skin is minimal, so the drug acts predominantly at the site of application with limited exposure to the rest of the body compared with the oral tablet.

• Oral Tablet: Swallow the Terfix tablet whole with a glass of water, at roughly the same time each day, with or without food.
• Oral Tablet: Complete the full prescribed course of Terfix even if the nail appears to have improved, since regrowth of a healthy nail continues for months after treatment ends.
• Oral Tablet: Attend any liver function tests recommended by the prescriber before and during treatment with Terfix.
• Topical Cream/Gel/Spray: Clean and dry the affected skin area before applying Terfix.
• Topical Cream/Gel/Spray: Apply a thin layer of Terfix to cover the affected area and a small margin of surrounding healthy skin, then gently rub in (for cream/gel) or spray evenly (for spray).
• Topical Cream/Gel/Spray: Wash hands thoroughly after applying Terfix, unless the hands are the area being treated.
• Topical Cream/Gel/Spray: Use Terfix for the full recommended duration, even if symptoms improve early, to reduce the chance of relapse.
• Topical Cream/Gel/Spray: Terfix topical forms are for external skin use only; avoid contact with eyes, mouth, and other mucous membranes, and do not apply to the nails or scalp.

• CYP2D6-metabolized drugs (e.g., tricyclic antidepressants, SSRIs, beta-blockers, class 1C antiarrhythmics, MAOI type B): Oral Terfix is a potent inhibitor of the CYP2D6 liver enzyme. Co-administration with drugs metabolized by CYP2D6 can significantly raise their blood levels, so such combinations require careful monitoring and may need a dose reduction of the other drug.
• Rifampin: Rifampin increases the clearance of Terfix by about 100%, which lowers Terfix blood levels and may reduce its effectiveness.
• Cimetidine: Cimetidine decreases the clearance of Terfix by about 33%, which raises Terfix blood levels.
• Fluconazole: Fluconazole increases Terfix exposure (peak level up about 52%, overall exposure up about 69%) due to inhibition of its metabolism.
• Cyclosporine: Terfix increases the clearance of cyclosporine by about 15%.
• Caffeine: Terfix reduces the clearance of caffeine by about 19%, prolonging its effects.
• Warfarin: There have been spontaneous reports of increased or decreased prothrombin time in patients taking Terfix together with warfarin; monitoring of clotting parameters is advisable.
• Topical formulations: Because topical Terfix cream, gel, and spray have minimal systemic absorption through intact skin, the clinically significant drug interactions described above relate specifically to the oral tablet.

Common Side Effects

Oral Tablet: Headache, diarrhea, rash, indigestion (dyspepsia), nausea, abdominal pain, flatulence, itching (pruritus), taste disturbance, and mild liver enzyme elevations are the most commonly reported effects of oral Terfix.

Topical Cream/Gel/Spray: Application-site irritation, burning, stinging, itching, redness, and dryness of the skin are the most commonly reported effects of topical Terfix.

Serious Side Effects – Seek Medical Attention

• Signs of liver injury with oral Terfix (persistent nausea, loss of appetite, unusual tiredness, vomiting, pain in the right upper abdomen, yellowing of the skin or eyes, dark urine, or pale stools) — see Precautions and Warnings for full details on this hepatotoxicity risk.
• Severe, prolonged, or permanent taste disturbance or loss of smell with oral Terfix.
• Signs of severe neutropenia or other blood disorders (fever, mouth sores, unusual bruising or bleeding, frequent infections) with oral Terfix.
• Serious skin reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, or DRESS syndrome (widespread rash, blistering, fever, swollen glands) with oral Terfix.
• New or worsening symptoms of lupus erythematosus (joint pain, skin rash on sun-exposed areas) with oral Terfix.
• Signs of thrombotic microangiopathy (unusual bruising, bleeding, extreme fatigue, confusion) — rare, reported with oral Terfix.
• New or worsening low mood, anxiety, or depressive symptoms with oral Terfix.
• Signs of a severe allergic reaction (swelling of the face, lips, tongue, or throat; difficulty breathing; severe rash) with oral or topical Terfix.
• Severe or worsening local irritation, blistering, or allergic contact dermatitis with topical Terfix that does not settle — stop use and consult a doctor.

Pregnancy

Oral Tablet: Available data on oral Terfix use in pregnant women are insufficient to establish whether it carries a drug-associated risk. Because onychomycosis is not a medically urgent condition, it is generally recommended that oral Terfix not be started during pregnancy; treatment can usually be postponed until after delivery.

Topical Cream/Gel/Spray: Systemic absorption of topical Terfix is minimal, but data specific to pregnancy are limited. Topical Terfix should be avoided during pregnancy unless a healthcare professional judges the benefit to outweigh the potential risk.

Breastfeeding

Oral Tablet: Terfix passes into human breast milk after oral dosing. Data on effects in the breastfed infant are lacking, so oral Terfix is generally not recommended while breastfeeding; a healthcare professional should weigh the benefits of breastfeeding against the potential risk.

Topical Cream/Gel/Spray: Terfix is also excreted into breast milk with topical use, and product labeling advises against use during breastfeeding; if a healthcare professional determines topical Terfix is necessary, application to the breast/chest area should be avoided.

• Hepatotoxicity with oral Terfix (important — read carefully): Rare cases of liver failure, sometimes leading to liver transplantation or death, have occurred with oral Terfix, including in patients with no pre-existing liver disease. Liver function tests should be performed before starting oral Terfix and monitored periodically during treatment. Oral Terfix should be discontinued immediately if there is biochemical or clinical evidence of liver injury. Patients should be told to report persistent nausea, loss of appetite, unusual fatigue, vomiting, right upper abdominal pain, yellowing of the skin or eyes, dark urine, or pale stools without delay. Oral Terfix is contraindicated in patients with chronic or active liver disease.
• Taste and smell disturbance: Oral Terfix can cause taste disturbance that may be severe, prolonged, or even permanent, sometimes leading to reduced food intake, weight loss, anxiety, or low mood; disturbance or loss of smell has also been reported and may likewise be prolonged or permanent. Terfix should be discontinued if either effect develops (see Side Effects).
• Depressive symptoms: Depressive symptoms have been reported with oral Terfix; patients and caregivers should watch for new or worsening low mood and report it promptly.
• Severe neutropenia and blood disorders: Rare but serious drops in white blood cell count (severe neutropenia) and other blood disorders have been reported with oral Terfix; unexplained fever, sore throat, or infection during treatment should be reported immediately.
• Serious skin reactions: Oral Terfix has rarely been associated with serious skin reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, and DRESS syndrome; Terfix should be stopped if a progressive skin rash develops.
• Lupus erythematosus: Oral Terfix may rarely trigger or worsen cutaneous or systemic lupus erythematosus; treatment should be discontinued if signs develop.
• Thrombotic microangiopathy: Rare, sometimes fatal, cases of thrombotic microangiopathy have been reported with oral Terfix; discontinue promptly if suggestive symptoms occur.
• External use only (topical forms): Topical Terfix cream, gel, and spray are for external skin use only. Avoid contact with the eyes, mouth, and other mucous membranes, and do not use inside the vagina, on the nails, or on the scalp.
• Hypersensitivity: Discontinue Terfix and seek medical care if signs of a serious allergic reaction (swelling of the face/throat, severe rash, difficulty breathing) occur.

Reported experience with oral Terfix overdose is limited. Doses of up to 5 grams (about 20 times the usual daily therapeutic dose) have been taken without causing serious adverse reactions; reported symptoms after overdose have included nausea, vomiting, abdominal pain, dizziness, rash, frequent urination, and headache. Specific toxic-dose thresholds beyond this have not been established.

If an overdose of Terfix is suspected, do not induce vomiting unless specifically directed to do so by a doctor or poison control service. Contact emergency medical services or a poison control center immediately, and take the Terfix package or container along for reference. Accidental ingestion of topical Terfix products should also be treated as a medical emergency requiring prompt professional advice.

Oral Tablet: Store Terfix tablets below 25°C, in a tightly closed container, protected from light.

Topical Cream/Gel/Spray: Store Terfix topical products at controlled room temperature, generally 20–25°C.

For any Terfix product, always keep out of reach of children and confirm storage instructions on the specific product's label, as conditions can vary slightly by manufacturer.

Children

Oral Tablet: The safety and effectiveness of oral Terfix have not been established in children for onychomycosis; oral Terfix tablets are generally not used in pediatric patients for this indication without specific medical justification.

Topical Cream/Gel/Spray: Topical Terfix is used in adults and children 12 years of age and older per product labeling; use in children under 12 years should only occur under the direction of a healthcare professional.

Elderly

Clinical experience with Terfix in patients 65 years and older is limited. No clinically important age-related change in blood levels has been identified, but because elderly patients more often have reduced liver, kidney, or heart function, oral Terfix should be used cautiously, generally starting at the lower end of the dosing range and with attention to concurrent illnesses and medications.

Renal Impairment

Oral Terfix has not been adequately studied in patients with creatinine clearance of 50 mL/min or less; clearance of Terfix is reduced by roughly half in this population, so oral Terfix should be used with caution and under close medical supervision in significant renal impairment. Topical Terfix has minimal systemic absorption and is not generally restricted on renal grounds, but should still be used as directed by a healthcare professional.

Hepatic Impairment

Oral Terfix is contraindicated in patients with chronic or active liver disease; clearance of Terfix is reduced by roughly half in patients with cirrhosis. See the Hepatotoxicity entry under Precautions and Warnings for full detail. Topical Terfix is not systemically restricted in liver disease because of its minimal absorption, but patients with significant liver disease should still discuss any use of Terfix, including topical forms, with their doctor.

Oral Tablet: Fingernail onychomycosis is typically treated with Terfix for 6 weeks; toenail onychomycosis is typically treated for 12 weeks. Visible improvement of the nail continues for several months after the course of Terfix ends, as it takes time for healthy nail to grow out.

Topical Cream/Gel: Tinea pedis between the toes is typically treated with Terfix for 1 week, and tinea pedis on the soles/sides of the foot for 2 weeks; tinea cruris and tinea corporis are typically treated for 1–2 weeks; cutaneous candidiasis and pityriasis versicolor are typically treated for 2 weeks.

Topical Spray: Tinea pedis, tinea cruris, and tinea corporis are typically treated with Terfix spray for 1 week; pityriasis versicolor is typically treated for 1 week with twice-daily application.

Actual duration of Terfix therapy should always be confirmed by the prescribing healthcare professional, as it can vary with infection severity and response to treatment.

Allylamine antifungal

Terbinafine Hydrochloride inhibits the fungal enzyme squalene epoxidase, an early and rate-limiting step in the biosynthesis of ergosterol, an essential component of the fungal cell membrane. This inhibition leads to a deficiency of ergosterol and an accumulation of squalene inside the fungal cell, which increases membrane permeability and results in fungal cell death.

Oral Tablet: Safety and efficacy of oral Terfix have not been established in children for the treatment of onychomycosis; oral Terfix is generally reserved for adults for this indication.

Topical Cream/Gel/Spray: Topical Terfix is labeled for use in adults and children 12 years of age and older for tinea pedis, tinea cruris, and tinea corporis. Use of topical Terfix in children younger than 12 years should be guided by a healthcare professional.