Terbinafine
Mechanism :
Terbinafine is an allylamine which has a broad spectrum of antifungal activity. At low concentrations terbinafine is fungicidal against dermatophytes, moulds and certain dimorphic fungi. The activity against yeasts is fungicidal or fungistatic, depending on the species. Terbinafine interferes specifically with fungal sterol biosynthesis by inhibition of squalene epoxidase in the fungal cell membrane. This leads to a deficiency in ergosterol and to an intracellular accumulation of squalene, resulting in fungal cell death.
Indication :
Contraindications :
Contraindicated in patients with a hypersensitivity to terbinafine or any of the excipients. Avoid contact with eyes.
Dosing :
Oral: Tinea capitis: Use in children >4 years of age.
<25 kg: 125 mg/day for 6 weeks.
25-35 kg: 187.5 mg/day for 6 weeks.
>35 kg: 250 mg/day for 6 weeks.
Topical: Use in children >12 years. Available as 1%w/w cream, lotion, gel.
Apply twice daily for 1-4 weeks.
Adverse Effect :
Headache, loss of appetite, dyspepsia, nausea, mild abdominal pain, diarrhea, urticaria. Rarely, Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis. If progressive skin rash occurs, treatment with terbinafine should be discontinued.
Interaction :
Rifampicin: Plasma concentration is reduced.
Cimetidine: Plasma concentration is increased.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | 100% on alternate days |
| 10-20 | 100% on alternate days |
| <10 | 100% on alternate days |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unlikely to be dialysed. Dose as in GFR<10 mL/min |
| HD | Unlikely to be dialysed. Dose as in GFR<10 mL/min |
| HDF/High flux | Unknown dialysability. Dose as in GFR<10 mL/min |
| CAV/VVHD | Unknown dialysability. Dose as in GFR=10–20 mL/min |
Hepatic Dose :
Avoid use in chronic or active hepatic disease.