Myconafine (Terbinafine)

Terbinafine is an allylamine antifungal used to treat infections caused by dermatophyte fungi.

• Onychomycosis: reduces fungal load in the nail plate, leading to gradual clearance of nail infection.
• Tinea pedis (athlete's foot): alleviates itching, scaling and redness by eradicating the causative fungus.
• Tinea corporis (ringworm): eliminates the dermatophyte from skin lesions, promoting healing and preventing spread.

• Terbinafine inhibits the fungal enzyme squalene epoxidase, a key step in ergosterol synthesis. By blocking this pathway, the drug causes accumulation of squalene and depletion of ergosterol, disrupting the integrity of the fungal cell membrane and leading to cell death. This selective action targets dermatophyte organisms while sparing human cells.

Terbinafine may cause a range of adverse reactions, most of which are mild and reversible.

Common Side Effects

• Gastrointestinal upset: nausea, abdominal discomfort or diarrhea.
• Altered taste sensation: dysgeusia or loss of taste.
• Headache: mild to moderate intensity.
• Skin rash: erythematous or pruritic lesions.
• Elevated liver enzymes: transient increases in hepatic transaminases.

Serious or Rare Side Effects

• Hepatotoxicity: signs of liver injury such as jaundice or severe enzyme elevation.
• Severe cutaneous reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Hematologic abnormalities: neutropenia, thrombocytopenia or anemia.
• Peripheral neuropathy: tingling or numbness in extremities.
• Visual disturbances: blurred vision or photophobia.

Before initiating therapy, clinicians should evaluate patient-specific factors and monitor for potential risks.

• Assess liver function: obtain baseline hepatic enzymes and repeat if clinically indicated.
• Review medication history: avoid concomitant use of drugs that may increase hepatic burden.
• Monitor for skin reactions: discontinue if severe rash or mucosal involvement occurs.
• Evaluate renal function: adjust use in severe renal impairment as per prescribing information.
• Counsel on taste changes: inform patients that dysgeusia is common and usually transient.
• Store at ambient temperature: keep below 25°C in the original packaging, protect from moisture.

Terbinafine can interact with several medicines, affecting its concentration or the safety of co‑administered agents.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may raise terbinafine plasma levels and increase toxicity risk.
• Rifampin or other CYP inducers: can markedly reduce terbinafine exposure, compromising efficacy.
• Warfarin: may potentiate anticoagulant effect, requiring closer INR monitoring.

Moderate Interactions (Monitor Closely)

• Oral contraceptives: terbinafine may reduce hormonal efficacy; advise additional contraceptive measures.
• Cimetidine: may increase terbinafine concentrations modestly.
• Antidepressants metabolized by CYP2D6: monitor for altered plasma levels.