What is the treatment regimen for fungal infections using Lamisil (terbinafine)?

Terbinafine (Lamisil) Treatment Regimen for Fungal Infections

Terbinafine 250mg once daily is the treatment of choice for dermatophyte onychomycosis, administered for 6 weeks for fingernail infections and 12 weeks for toenail infections, with mycological cure rates of 70-80% for toenails and 80-90% for fingernails. 1

Dosage and Duration

Oral Terbinafine Regimen

• Fingernail infections: 250mg once daily for 6 weeks 2
• Toenail infections: 250mg once daily for 12 weeks 2
• Can be taken with or without food 2
• Optimal clinical effect is seen months after completing treatment due to time required for healthy nail outgrowth 2

Topical Terbinafine Options

For patients unable to tolerate oral therapy or with contraindications:

• Topical formulations (1% cream/solution) applied once or twice daily for up to 2 weeks 1
• Mycological cure rates >80% for tinea pedis, tinea corporis/cruris, cutaneous candidiasis and pityriasis versicolor with topical application 1

Pre-Treatment Assessment

• Diagnosis should be confirmed through microscopic examination with potassium hydroxide (KOH), mycological culture, or nail biopsy before initiating treatment 1
• Liver function tests (ALT and AST) should be performed before starting terbinafine 2
• Assess for contraindications:
  • Liver disease
  • Lupus erythematosus
  • Immunocompromised status
  • Kidney problems 2

Monitoring and Side Effects

Common Side Effects

• Headache, diarrhea, rash, dyspepsia, pruritus, taste disturbance, nausea, abdominal pain, and flatulence 2

Serious Side Effects Requiring Immediate Attention

1. Liver problems: Monitor for symptoms such as nausea, anorexia, fatigue, vomiting, right upper abdominal pain, jaundice, dark urine, or pale stools 2
2. Taste/smell disturbances: May improve after stopping treatment but can be permanent 2
3. Serious skin reactions: Including rash, hives, mouth sores, skin blistering/peeling 2
4. Lupus erythematosus: Watch for erythema, scaling, loss of pigment, and unusual photosensitivity 2
5. Depressive symptoms: Including mood changes, sleep pattern changes, loss of energy 2

Drug Interactions

Terbinafine has fewer drug interactions compared to azole antifungals 1, but be cautious with:

• Antidepressants
• Antihypertensives
• Cardiac medications
• Desipramine
• Caffeine
• Cyclosporine
• Fluconazole
• Rifampin
• Cimetidine 2

Special Populations

Diabetic Patients

• Terbinafine is preferred due to lower risk of drug interactions 1
• Topical treatments are appropriate for mild-to-moderate infections where risk of drug interaction is high 1

HIV/Immunosuppressed Patients

• Terbinafine and fluconazole are preferred due to lower risk of interactions with antiretrovirals 1
• Consider topical options when systemic therapy is contraindicated 1

Pregnancy and Breastfeeding

• Safety not established; avoid use during pregnancy without consulting physician 2
• Terbinafine passes into breast milk; discuss feeding options with physician 2

Prevention of Reinfection

• Keep nails short and clean
• Dry feet thoroughly after bathing
• Wear cotton, absorbent socks and change daily
• Apply antifungal powders to shoes and feet
• Avoid sharing nail clippers
• Wear protective footwear in public areas
• Treat concomitant fungal infections promptly 1

Treatment Outcomes and Follow-up

• Mean time to overall success: approximately 10 months for toenail infections and 4 months for fingernail infections 2
• Clinical relapse rate: approximately 15% at one year after completing therapy 2
• Mycological cure rates generally improve after treatment cessation due to the drug's fungicidal mechanism and residual effect in tissue 3

Common Pitfalls to Avoid

1. Not confirming diagnosis before initiating treatment
2. Inadequate treatment duration
3. Simultaneous use of corticosteroids with antifungals
4. Having unrealistic expectations about the speed of improvement
5. Not addressing predisposing factors
6. Not implementing preventive measures to avoid reinfections 1

Terbinafine has demonstrated greater effectiveness than itraconazole, fluconazole, and griseofulvin in randomized trials for dermatophyte onychomycosis, making it the treatment of choice for these infections 4.