Antimicrobials/Antifungallow yield

Antifungals

also: fluconazole · nystatin · amphotericin · azole · terbinafine

Overview

Antifungals for candidiasis, dermatophytes and invasive fungal infection. The azole CYP interactions and amphotericin nephrotoxicity are key.

Mechanism

Azoles inhibit ergosterol synthesis (lanosterol 14α-demethylase, CYP-dependent). Polyenes (amphotericin/nystatin) bind ergosterol → membrane pores. Terbinafine inhibits squalene epoxidase.

The agents

Fluconazoleazole

oral/IV

Candida (vaginal single 150 mg), cryptococcal; CYP inhibitor (warfarin/statins); teratogenic high-dose; QT.

Nystatinpolyene (topical)

Oral/perioral candida (not absorbed).

Amphotericin Bpolyene (IV)

Invasive fungal infection; "ampho-terrible" — nephrotoxicity, hypokalaemia, infusion reactions.

Terbinafineallylamine

oral

Onychomycosis; hepatotoxic — check LFTs (cross-ref derm).

Adverse effects

Azoles: hepatotoxicity + CYP interactions + QTserious

Amphotericin: nephrotoxicity, hypokalaemia/hypomagnesaemia, infusion reactionsserious

Terbinafine: hepatotoxicity, taste disturbancecommon

Cautions & contraindications

Azoles in pregnancy (high dose)pregnancy

Teratogenic.

Azole + simvastatin / warfarinall

CYP inhibition.

Interactions

Azoles inhibit CYP3A4 (statins, warfarin, DOACs, calcineurin inhibitors)

Monitoring & kinetics

LFTs (oral azoles/terbinafine); U&E/Mg (amphotericin)

Topical for localised; oral/IV for systemic.

Choosing it

Spectrum: Azoles (fluconazole): Candida, Cryptococcus. Polyenes (nystatin topical; amphotericin systemic): broad. Terbinafine: dermatophytes (cross-ref derm).

Source: BNF — Antifungals