Pharm

Permethrin

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Permethrin, Elimite, Nix

  • See Also
  1. Pesticide
  2. Pyrethroid Toxicity
  • Mechanism
  1. Pyrethroid (Synthetic based on Pyrethrins)
  2. Neurotoxin
    1. Acts at the Neuron cell membrane of arthropods (e.g. fleas, lice, mites, ticks)
    2. Binds Sodium channels and prolongs their activation
  • Indications
  1. Pediculosis (Lice)
  2. Scabies
  3. Prevention of Vector-borne Infection
  • Advantages
  1. Residual activity for over 2 weeks
  • Precautions
  1. Avoid in under age 2 months old
  2. Safe: Poorly absorbed
  3. Rapidly metabolized to inactive
  • Pregnancy and Lactation
  1. Pregnancy Category B
  2. Lactation safety is unknown
    1. Consider switching to formula while using Permethrin
  • Preparations
  1. Permethrin 1% (Nix rinse supplied as 60 ml)
    1. Over the counter
  2. Permethrin 5% (Elimite supplied as 60 g cream)
    1. FDA indication only for Scabies
  • Dosing
  1. Scabies treatment (Permethrin 5%)
    1. Apply Permethrin 5% cream from head to soles of feet
      1. Adults and children over age 5 years apply from neck down
      2. Consider forhead application in the elderly
    2. Avoid Mouth, nose and eyes
    3. Wash after 8-14 hours
    4. Repeat application in 1-2 weeks
  2. Lice treatment (Permethrin 1%)
    1. Apply to clean dry hair
    2. Saturate hair and scalp
    3. Wash after 10 minutes
    4. Consider overnight treatment
      1. Leave on overnight for 8-14 hours under shower cap
      2. Rinse hair in morning
    5. Repeat in one week
  • Supply
  1. Adult: 60 grams per adult per treatment (120 g total)
  2. Child: 30 grams per child per treatment (60 g total)
  • Efficacy
  1. Resistance increasing to 1% Permethrin
  2. Lice Treatment may require 5% Permethrin
  • Adverse Effects
  1. See Pyrethrin
  2. See Pyrethroid Toxicity
  3. Mild transient burning, Paresthesias or Pruritus at the application site
  4. Local erythema may occur
  • References
  1. Marco (2013) Crit Dec in Emerg Med 27(1): 2-7
  2. Mumcuoglo (1995) Med Vet Entomol, 9:427 [PubMed]
  3. Rupes (1995) Cent Eur J Public Health, 3:30 [PubMed]