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BackPermethrin Data - Uses, Dosage, Drug class, Brand name, Warnings, etc
| Pharmacology | Permethrin, a pyrethroid, acts on arthropod nerve cell membranes, causing delayed polarization, paralysis, and death. It is active against lice (including unhatched eggs) and mites (e.g., scabies). |
|---|---|
| Administration and Adult Dosage |
- Topical for head lice: Apply 1% cream rinse to washed, towel-dried hair; leave on ≤10 min, rinse with water; reapply after >7 days if live lice persist - Topical for pubic lice: Not FDA-approved, but 5% cream applied as for scabies, repeat at 10 days - Topical for scabies: Massage 5% cream into skin from head to soles; remove by showering/bathing after 8–14 hr |
| Special Populations - Pediatric Dosage |
- <2 months: Safety and efficacy not established - Topical for lice (>2 months): Same as adult dosage - Topical for scabies (>2 months): Same as adult dosage; for neonates, remove cream after 6 hr |
| Special Populations - Geriatric Dosage | Same as adult dosage. |
| Dosage Forms |
- Liquid (Creme Rinse): 1% (Nix, various) - Cream: 5% (Acticin, Elimite) |
| Patient Instructions |
- Lice: Wash hair, towel dry; apply 1% creme rinse to saturate hair/scalp, especially behind ears and nape; leave on ≤10 min, rinse; use provided comb to remove nits; wash bedding, pajamas, towels in hot, soapy water, dry on hot cycle ≥20 min; seal non-washable items in plastic bags for 2 weeks or dry clean; soak combs in hot water 5–10 min; consult provider for eyebrow/eyelash infestation - Scabies: Itching, mild burning, or stinging may occur post-application; itching usually resolves by 4 weeks; consult provider if irritation persists |
| Missed Doses | - Not applicable; applied as a single or repeat treatment |
| Pharmacokinetics - Fate |
- Absorption: <2% absorbed topically - Metabolism: Rapid ester hydrolysis to inactive metabolites - Excretion: Metabolites excreted in urine |
| Adverse Reactions & Side Effects |
Lice (1% cream rinse): - Mild, occasional reactions Scabies (5% cream): - Mild, transient burning, stinging, tingling (~10% of patients) - Itching, edema, erythema (often scabies-related, temporarily exacerbated) - Intolerable burning/stinging in AIDS patients with scabies - Persistent itching/irritation post-treatment due to allergic reactions to dead mites Rare: - Allergic reactions (possibly due to formaldehyde preservative) |
| Contraindications | - Documented allergy to pyrethroids or vehicle components |
| Precautions & Warnings |
- Use cautiously in pregnancy; no teratogenicity in animal studies - During lactation: Temporarily discontinue nursing with 5% cream; 1% creme rinse poses minimal risk - Avoid contact with eyes and mucous membranes |
| Drug Interactions | - None known |
| Parameters to Monitor | - Check for parasites 7–10 days post-lice treatment or 14 days post-scabies treatment |
| Class and Drug Brand Name |
- Class: Pyrethroid Antiparasitics - Brand Names: Acticin, Elimite, Nix, Various |
| Notes |
- Drug of choice for pediculosis and scabies - Safer, more effective than lindane for scabies; more effective/easier to use than crotamiton - Malathion 0.5% lotion (Ovide) is an alternative for pediculosis - Synergized pyrethrins require repeat treatment after 1 week, less persistent than permethrin - Lindane not recommended due to resistance and environmental persistence |
References
Hand of Clinical Drug Data