PERMETHRIN
PERMETHRIN  (per-meth'rin)  Nix, Elimite, Acticin Classifications: scabicide; pediculicide; Therapeutic: scabicide; pediculicide Pregnancy Category: B |
Availability
5% cream; 1% liquid
Action
Pediculicidal and ovicidal activity against Pediculus humanus var. capitis (head louse). Inhibits sodium ion influx through nerve cell membrane channels, resulting in delayed repolarization of the action potential and paralysis of the pest.
Therapeutic Effect
It prevents burrowing into host's skin. Since lice are completely dependent on blood for survival, they die within 24–48 h. Also active against ticks, mites, and fleas.
Uses
Pediculosis capitis.
Contraindications
Hypersensitivity to pyrethrins, chrysanthemums, sulfites, or other preservatives or dyes; acute inflammation of the scalp; lactation.
Cautious Use
Children <2 y (liquid), and <2 mo (lotion); asthma; pregnancy (category B).
Route & Dosage
| Head Lice Adult/Child (>2 y): Topical Apply sufficient volume to clean wet hair to saturate the hair and scalp; leave on 10 min, then rinse hair thoroughly |
Administration
Topical- Saturate scalp as well as hair with the lotion; this is not a shampoo.
- Hair should be washed with regular shampoo before treatment with permethrin, thoroughly rinsed and dried.
- Shake lotion well before application. One container holds enough for at least one treatment, but two containers may be necessary if patient has long hair.
- Rinse hair and scalp thoroughly and dry with a clean towel following 10 min exposure to the medication. Head lice are usually eliminated with one treatment.
- Store drug away from heat at 15°–25° C (59°–77° F) and direct light. Avoid freezing.
Adverse Effects (≥1%)
Skin: Pruritus, transient tingling, burning, stinging, numbness; erythema, edema, rash.Pharmacokinetics
Absorption: <2% of amount applied is absorbed through intact skin. Metabolism: Rapidly hydrolyzed to inactive metabolites. Elimination: Primarily in urine.Nursing Implications
Assessment & Drug Effects
- Do not attempt therapy if patient is known to be sensitive to any pyrethrin or pyrethroid. Stop treatment if a reaction occurs.
Patient & Family Education
- When hair is dry, comb with a fine-tooth comb (furnished with medication) to remove dead lice and remaining nits or nit shells.
- Be aware that drug remains on hair shaft up to 14 d; therefore, recurrence of infestation rarely occurs (<1%).
- Inspect hair shafts daily for at least 1 wk to determine drug effectiveness. Contact physician if live lice are observed after 7 d. A renewed prescription for a second treatment may be ordered. Signs of inadequate treatment: Itching, redness of skin, skin abrasion, infected scalp areas.
- Resume regular shampooing after treatment; residual deposit of drug on hair is not reduced.
- Be aware that drug is usually irritating to the eyes and mucosa. Flush well with water if medicine accidentally gets into eyes.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; 
Canadian drug name; Prototype drug