Antifungal Drug Overview (PDF)

Overview of the Drug Class **Prototype: terbinafine (Lamisil) ** - **Category**: Allylamine Antifungal Agent  - **Primary Function**: Terbinafine is a highly active antifungal agent against dermatophytes with less activity against Candida species.  - **Unique Features**: Other agen...

Overview of the Drug Class **Prototype: terbinafine (Lamisil) ** - **Category**: Allylamine Antifungal Agent  - **Primary Function**: Terbinafine is a highly active antifungal agent against dermatophytes with less activity against Candida species.  - **Unique Features**: Other agents representative of this class includes naftifine.   Mechanism of Action - Terbinafine inhibits squalene epoxidase with resultant inhibition of ergosterol synthesis. Ergosterol synthesis is a key component of the fungal cell membrane.  **Image Title: Mechanism of antifungal drugs** - Cell wall - Cell membrane - DNA - Proteins - Echinocandins, triterpenoids - Azoles, polyenes, allylamines - 5-fluorocytosine - Sordarins Indications and Therapeutic Uses - **Systemic Fungal Infections**: Oral Terbinafine is indicated for systemic fungal infections like tinea and onychomycosis. - **Superficial Fungal Infections**: Topical Terbinafine is indicated for superficial fungal infections like tinea infections, including corporis, cruris, and pedis. Side Effects and Adverse Reactions **Side Effect** **Description** ------------------- ------------------------------------------------------------------------------------------------------------- GI Upset Diarrhea, dyspepsia, and abdominal pain are common. Skin Reactions This dermatologic side effect can occur. Taste Disturbance Alterations in this sense can occur. Hepatotoxicity This adverse effect is an adverse effect of terbinafine with reports of liver transplantation and fatality. Precautions and Contraindications **Contraindications:**  - Contraindicated for clients with preexisting hepatic disease.  Drug Interactions - Terbinafine is antagonized by **\[rifampin**\] when taken orally.  - Terbinafine plasma levels may be increased by **\[cimetidine\]** or **\[CYP2C9 and CYP3A4\]** inhibitors such as **\[fluconazole, ketoconazole, amiodarone\]**.  - Terbinafine may potentiate the effects of **\[caffeine\]** or drugs metabolized by CYP2D6, such as **\[tricyclic antidepressants, SSRIs, and beta-blockers\]**.  Dosing, Administration, & Client Teaching **Dosing** - Dosing varies based on the condition, severity, and client response.  - Check drug dosing guidelines for individualized dosing.  - Oral terbinafine is available in 250 mg tablets.    - Oral terbinafine for nail infection is 250 mg/day for 6-12 weeks.  - Oral terbinafine for tinea is 250 mg/day for 2-6 weeks.  - Topical terbinafine 1% is available in gel, spray, powder, and cream formulations with application once or twice daily for 1-4 weeks.  **Administration** - Oral or topical administration. **Client Teaching** - Clients should be educated on signs of hepatic dysfunction and counseled to discontinue therapy immediately and seek medical evaluation.  Labs to Monitor **Liver Function Tests (LFTs)** - Baseline LFTs (serum alanine and aspartate aminotransferases) are recommended with oral dosing.