Permethrin

INTRODUCTION

Indications

1% lotion: Eradication of Pediculus humanus capitis (head lice and their eggs): Prevention of infestation of head lice during epidemics. 5% cream: Eradication of Sarcoptes scabiei (scabies).

Action

Causes repolarization and paralysis in lice by disrupting sodium transport in normal nerve cells. Therapeutic Effects: Death of parasites.

Adverse Reactions/Side Effects

Derm: burning, itching, rash, redness, stinging, swelling. Neuro: numbness, tingling.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Monitor symptoms such as itching scalp to help document drug effectiveness.

Interventions

• Avoid contact with infected areas or wear protective gloves when treating patient.

• Always wash hands thoroughly and disinfect bedding and equipment (whirlpools, electrotherapeutic devices, treatment tables, and so forth) to help prevent the spread of infection.

Patient/Client-Related Instruction

• Advise patient to report any increased local sensitivity to this drug (pain, burning, itching, stinging, swelling, numbness, tingling).

• Instruct patient about proper hygiene; e.g., clean or discard infected clothing, not share combs and hats with others, thoroughly wash and dry the scalp, and so forth.

• Advise patient to apply the drug as directed; that is, apply the drug topically for the recommended period of time before washing off.

Pharmacokinetics

Absorption: Small amounts (<2%) systemically absorbed. Remains on hair for 10 days.

Distribution: Unknown.

Metabolism and Excretion: Rapidly inactivated by enzymes.

Half-life: Unknown.

Contraindications/Precautions

Contraindicated in: Hypersensitivity to permethrin, pyrethrins (insecticides or veterinary pesticides), chrysanthemums, or isopropyl alcohol.

Use Cautiously in: Pregnancy or lactation; Children <2 yr (1% lotion); Children <2 mo (5% cream).

Interactions

Drug-Drug: No significant interactions.

Route/Dosage

Head Lice (Treatment and Prevention)

Topical (Adults and Children >2 yr): 1% lotion applied to the hair, left on for 10 min, then rinsed, for 1 application.

Scabies

Topical (Adults and Children): Massage 5% cream into all skin surfaces. Leave on for 8–14 hr, then wash off.

Topical (Infants >2 mo): Massage 5% cream into hairline, scalp, neck, temple, and forehead. Leave on for 8–14 hr, then wash off.

Availability (generic available)

Liquid cream rinse (lotion): 1% in 60-mL containers OTC. Cream: 5% in 60-g tube.