Terfix
Generic Name
terfix-250-mg-tablet
Manufacturer
Square Pharmaceuticals Ltd.
Country
Bangladesh
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Price Details
Current market pricing information
| Variant | Unit Price | Strip Price |
|---|---|---|
| terfix 250 mg tablet | ৳ 40.00 | ৳ 400.00 |
Description
Overview of the medicine
Terfix-250 mg Tablet contains Terbinafine, an allylamine antifungal, used to treat fungal infections of the skin, hair, and nails, including onychomycosis, tinea corporis, tinea cruris, and tinea pedis.
Uses & Indications
Dosage
Adults
Onychomycosis: 250 mg once daily for 6 to 12 weeks. Tinea corporis/cruris: 250 mg once daily for 2 to 4 weeks. Tinea pedis: 250 mg once daily for 2 to 6 weeks. Tinea capitis: 250 mg once daily for 4-6 weeks (off-label).
Elderly
No specific dose adjustment is generally required, but caution is advised in elderly patients with pre-existing hepatic or renal impairment.
Renal_impairment
Use with caution. Consider dose reduction (e.g., to 125 mg daily) if creatinine clearance is less than 50 mL/min.
How to Take
Take the tablet orally, with or without food. It is important to complete the full course of treatment as prescribed by your doctor, even if symptoms improve.
Mechanism of Action
Terbinafine interferes with fungal ergosterol biosynthesis by inhibiting squalene epoxidase, an enzyme in the fungal sterol pathway. This leads to a deficiency in ergosterol and an intracellular accumulation of squalene, resulting in fungal cell death.
Pharmacokinetics
Onset
Clinical improvement typically observed within weeks, but full mycological cure and nail clearance for onychomycosis may take several months (up to 6-12 months) due to slow nail growth.
Excretion
Approximately 70-80% of the dose is excreted in urine, primarily as metabolites. Renal and hepatic impairment can decrease clearance.
Half life
Terminal elimination half-life is approximately 200-400 hours (8-17 days), with an initial distribution half-life of about 0.8 hours.
Absorption
Well absorbed from the gastrointestinal tract (>70%), but absolute bioavailability is reduced (about 40%) due to first-pass metabolism. Peak plasma concentrations are reached within 2 hours.
Metabolism
Extensively metabolized in the liver by at least seven cytochrome P450 isoenzymes (primarily CYP2C9, CYP1A2, CYP3A4, CYP2C8, and CYP2D6) to inactive metabolites.
Side Effects
Contraindications
- Hypersensitivity to terbinafine or any other component of the tablet.
- Active or chronic liver disease.
- Severe renal impairment (creatinine clearance <50 mL/min).
Drug Interactions
Caffeine
Terbinafine may inhibit the metabolism of caffeine, potentially increasing caffeine levels.
Warfarin
Rare cases of changes in INR have been reported with concomitant use; monitor INR closely.
Cimetidine
May decrease the clearance of terbinafine, increasing its plasma levels.
Rifampicin
May increase the clearance of terbinafine, potentially reducing its effectiveness.
CYP2D6 inhibitors (e.g., paroxetine, fluoxetine)
May reduce the metabolism of terbinafine, leading to increased exposure.
Storage
Store in a cool, dry place below 30°C. Protect from light and moisture. Keep out of reach of children.
Overdose
Symptoms of overdose may include nausea, vomiting, abdominal pain, dizziness, and rash. Management is symptomatic and supportive; gastric lavage may be considered.
Pregnancy & Lactation
Pregnancy Category B. Use in pregnancy only if clearly needed and the potential benefits outweigh the risks. Terbinafine is excreted in breast milk; therefore, breastfeeding is not recommended during treatment.
Side Effects
Contraindications
- Hypersensitivity to terbinafine or any other component of the tablet.
- Active or chronic liver disease.
- Severe renal impairment (creatinine clearance <50 mL/min).
Drug Interactions
Caffeine
Terbinafine may inhibit the metabolism of caffeine, potentially increasing caffeine levels.
Warfarin
Rare cases of changes in INR have been reported with concomitant use; monitor INR closely.
Cimetidine
May decrease the clearance of terbinafine, increasing its plasma levels.
Rifampicin
May increase the clearance of terbinafine, potentially reducing its effectiveness.
CYP2D6 inhibitors (e.g., paroxetine, fluoxetine)
May reduce the metabolism of terbinafine, leading to increased exposure.
Storage
Store in a cool, dry place below 30°C. Protect from light and moisture. Keep out of reach of children.
Overdose
Symptoms of overdose may include nausea, vomiting, abdominal pain, dizziness, and rash. Management is symptomatic and supportive; gastric lavage may be considered.
Pregnancy & Lactation
Pregnancy Category B. Use in pregnancy only if clearly needed and the potential benefits outweigh the risks. Terbinafine is excreted in breast milk; therefore, breastfeeding is not recommended during treatment.
Frequently Asked Questions
Common questions about this medicine
Pack Sizes
Shelf Life
3 years from manufacturing date
Availability
Available in pharmacies and hospitals
Approval Status
Approved by DGDA
Patent Status
Expired
Clinical Trials
Numerous clinical trials have established the efficacy and safety of oral terbinafine for the treatment of dermatophyte infections, particularly onychomycosis, demonstrating high cure rates compared to placebo and other antifungals.
Lab Monitoring
- Liver function tests (LFTs) should be performed before initiating treatment and periodically during treatment (e.g., after 4-6 weeks), especially if treatment exceeds 6 weeks or symptoms suggestive of liver dysfunction occur.
- Complete blood count (CBC) monitoring may be considered in patients with prolonged treatment or if symptoms suggestive of blood dyscrasias develop.
Doctor Notes
- Emphasize patient education regarding the importance of treatment adherence, completing the full course, and awareness of potential liver-related adverse effects.
- Baseline and periodic LFTs are critical, especially during prolonged therapy or if symptoms of hepatic dysfunction arise. Discontinue if LFTs indicate significant liver injury.
- Counsel patients on potential drug interactions, particularly with CYP2D6 inhibitors/inducers, and avoid concomitant alcohol use.
Patient Guidelines
- Always complete the full prescribed course of Terfix-250 mg Tablet, even if your symptoms improve, to ensure complete eradication of the infection and prevent recurrence.
- Immediately report any symptoms of liver problems such as persistent nausea, vomiting, dark urine, pale stools, yellowing of skin or eyes (jaundice), or unusual tiredness.
- Avoid alcohol consumption during treatment, particularly if you have a history of liver disease.
- Inform your doctor about all other medications, including over-the-counter drugs and herbal supplements, you are taking.
Missed Dose Advice
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Driving Precautions
Terbinafine may cause dizziness or visual disturbances in some patients. Patients should be cautioned about operating machinery or driving if they experience these side effects.
Lifestyle Advice
- Maintain good personal hygiene to prevent reinfection and spread of fungus.
- Keep affected areas clean and dry. Change socks and footwear frequently if treating foot infections.
- Avoid sharing personal items like towels, shoes, and clothing to prevent fungal spread.
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