terbinafine hydrochloride

terbinafine hydrochloride

Desenex Max, Lamisil, Lamisil AT

Pharmacologic class: Synthetic allylamine derivative

Therapeutic class: Antifungal

Pregnancy risk category B

Action

Unclear. Thought to interfere with sterol biosynthesis of fungal cell membrane permeability by inhibiting enzymes responsible for normal fungal growth and maturation, resulting in cell death.

Availability

Cream: 1%

Tablets: 250 mg

⊘Indications and dosages

➣ Tinea cruris; tinea corporis; tinea pedis; tinea versicolor

Adults and children: Massage cream into affected area and surrounding area once or twice daily for 7 to 14 days, not to exceed 4 weeks.

➣ Onychomycosis of fingernail or toenail

Adults: For fingernail infection, 250 mg P.O. daily for 6 weeks. For toenail infection, 250 mg P.O. daily for 12 weeks.

Contraindications

• Hypersensitivity to drug or its components
• Chronic active hepatic disease

Precautions

Use cautiously in:
• renal impairment (use not recommended)
• pregnant or breastfeeding patients (use not recommended)
• children (safety and efficacy not established).

Administration

• Give with or without food, but not with coffee, cola, or tea.
• Don't put occlusive dressing over affected area after cream application.

Route	Onset	Peak	Duration
P.O.	Unknown	≤ 2 hr	Unknown
Topical	Unknown	Unknown	Unknown

Adverse reactions

CNS: headache

EENT: visual disturbances

GI: nausea, diarrhea, dyspepsia, abdominal pain, flatulence

Hematologic: neutropenia

Hepatic: hepatic failure

Skin: burning, stinging, dryness, itching, and local irritation (with topical form); rash; pruritus; urticaria; erythema multiforme; Stevens-Johnson syndrome

Other: taste disturbances

Interactions

Drug-drug. Cimetidine: decreased terbinafine clearance

Cyclosporine: increased cyclosporine clearance

Dextromethorphan: increased dextromethorphan blood level

Rifampin: increased terbinafine clearance

Warfarin: altered warfarin efficacy

Drug-diagnostic tests. Hepatic enzymes: increased levels

Neutrophils: decreased count

Drug-food. Caffeine-containing foods and beverages: decreased caffeine clearance

Drug-herbs. Chaparral, comfrey, germander, jin bu huan, kava, pennyroyal: increased risk of hepatotoxicity

Cola nut, guarana, yerba maté: decreased clearance of these herbs

Patient monitoring

• Monitor CBC and liver function tests.
☞ Watch for signs and symptoms of erythema multiforme. Report early indications before they progress to Stevens-Johnson syndrome.

Patient teaching

• Tell patient he may take with or without food.
• Instruct patient to avoid coffee, tea, and colas, which can worsen adverse drug reactions.
• Tell patient drug may take 4 weeks to be effective in fingernail infections and 10 weeks in toenail infections. Urge him to keep taking it even though symptoms don't improve right away.
☞ Advise patient to immediately report rash, sore throat, cough, fever, or yellowing of skin or eyes.
• Instruct patient not to place occlusive dressing over affected area after applying cream.
• Caution patient not to let cream contact eyes, nose, or mouth.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and herbs mentioned above.