Home Drug Guide Terbinafine

Drug Guide

Generic Name

Terbinafine

Brand Names Lamisil, Lamisil At

Classification

Therapeutic: Antifungal

Pharmacological: allylamine antifungal

FDA Approved Indications

  • Onychomycosis (nail fungus) caused by dermatophytes
  • Superficial dermatophyte infections (tinea corporis, tinea cruris, tinea pedis)

Mechanism of Action

Inhibits fungal squalene epoxidase, leading to a decrease in ergosterol synthesis, an essential component of fungal cell membranes, resulting in cell death.

Dosage and Administration

Adult: 250 mg once daily for 6 weeks (finger nails) or 12 weeks (toe nails); topical formulations vary

Pediatric: Safety and efficacy not established in children under 4 years for topical use; consult specific product guidelines for other uses

Geriatric: Use with caution; adjust dose if necessary based on hepatic and renal function

Renal Impairment: No dosage adjustment for mild to moderate impairment; use caution in severe impairment

Hepatic Impairment: Avoid in active hepatic disease; monitor liver function closely if treatment is necessary

Pharmacokinetics

Absorption: Well absorbed from the gastrointestinal tract

Distribution: Widely distributed, including skin, nails, and adipose tissue; high affinity for keratinized tissue

Metabolism: Primarily via hepatic CYP450 enzymes (notably CYP2D6 and CYP1A2)

Excretion: Primarily through feces; minor amount in urine

Half Life: Approximately 36 hours

Contraindications

  • Hypersensitivity to terbinafine or any component of the formulation

Precautions

  • Liver disease, or history of hepatic impairment; monitor liver function during therapy
  • Use caution in patients with autoimmune diseases or hematologic disorders

Adverse Reactions - Common

  • Gastrointestinal disturbances (dyspepsia, diarrhea) (Common)
  • Headache (Common)
  • Rash, pruritus (Common)

Adverse Reactions - Serious

  • Hepatotoxicity (elevated liver enzymes, hepatitis, failure) (Rare but serious)
  • Taste disturbance (dysgeusia) (Uncommon)
  • Stevens-Johnson syndrome, toxic epidermal necrolysis (Rare)

Drug-Drug Interactions

  • CYP450 inhibitors or inducers (e.g., cimetidine, rifampin, ketoconazole) may alter terbinafine levels

Drug-Food Interactions

  • Limited data, generally none significant

Drug-Herb Interactions

  • Avoid herbal preparations that may affect CYP450 enzymes

Nursing Implications

Assessment: Monitor liver function tests prior to and during therapy; assess fungal infection response

Diagnoses:

  • Impaired skin integrity related to fungal infection
  • Risk for hepatotoxicity

Implementation: Administer with or without food; counsel patient on adherence; monitor for side effects

Evaluation: Infection resolution; normal liver function tests; absence of adverse effects

Patient/Family Teaching

  • Complete full course of therapy even if symptoms improve
  • Report signs of hepatotoxicity (jaundice, dark urine, fatigue)
  • Avoid alcohol during treatment
  • Inform about possible taste disturbances

Special Considerations

Black Box Warnings:

  • Hepatotoxicity: Liver damage has been reported; monitor liver function closely

Genetic Factors: No known significant genetic factors affecting response

Lab Test Interference: May cause elevated hepatic enzymes; interpret with caution

Overdose Management

Signs/Symptoms: Gastrointestinal symptoms, dizziness, headache, hypersensitivity reactions

Treatment: Supportive care; no specific antidote; consult poison control for management

Storage and Handling

Storage: Store at 20-25°C (68-77°F), protected from moisture and light

Stability: Stable under recommended conditions for the duration of the expiration date

🛡️ 5 Critical Medication Safety Tips for Nurses

1

Triple-Check High-Risk Medications

Always have another nurse verify insulin, heparin, warfarin, and chemotherapy drugs. These "high-alert" medications cause the most serious errors. Check concentration, dose calculation, and pump settings twice.

2

Know Look-Alike, Sound-Alike Drugs

Common mix-ups: hydromorphone/morphine, Celebrex/Celexa, Zyprexa/Zyrtec. Always use BOTH generic and brand names, read labels twice, and use barcode scanning when available. One wrong letter can be fatal.

3

Assess Before AND After Giving Meds

Check vitals before cardiac meds, pain levels before analgesics, and blood glucose before insulin. Always reassess within 30 minutes to evaluate effectiveness and watch for adverse reactions.

4

Watch for Drug Interactions

Common dangerous combinations: warfarin + aspirin (bleeding), ACE inhibitors + potassium (hyperkalemia), digoxin + diuretics (toxicity). Always check drug interactions before administering new medications.

5

Educate Your Patients

Teach patients medication names, purposes, major side effects, and what to report. Informed patients catch errors and improve compliance. Always encourage questions - an educated patient is a safer patient.

⚡ Remember: When in doubt, don't give it out! It's always safer to double-check than regret later.

⚠️ Medical Disclaimer

This drug guide is for educational purposes only and is NOT intended for clinical use. Always consult current prescribing information, healthcare providers, and institutional protocols before administering any medication. Do not use this information for patient care decisions.