II. Indications

III. Contraindications

  1. Age <2 months

IV. 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

V. Precautions

  1. Avoid in under age 2 months old
  2. Safe: Poorly absorbed
  3. Rapidly metabolized to inactive

VI. Medications

  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
    2. Adult: 60 grams per adult per treatment (120 g total)
    3. Child: 30 grams per child per treatment (60 g total)

VII. Dosing

  1. Scabies Treatment (Permethrin 5%, FDA approved for age >2 months)
    1. Apply Permethrin 5% cream from head to soles of feet, massaging onto surface
      1. Adults and children over age 5 years apply from neck down
      2. Consider forhead application in the elderly
      3. Include nail beds in application
      4. Avoid mouth, nose and eyes
    2. Wash off after 8-14 hours
    3. Repeat application in 1-2 weeks
  2. Lice Treatment (Permethrin 1%, FDA approved for age >2 years)
    1. Apply to clean dry hair
    2. Saturate hair and scalp
    3. Wash off 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

VIII. Pharmacokinetics

  1. Residual activity for over 2 weeks after application

IX. 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

X. Safety

  1. Pregnancy Category B
  2. Lactation safety is unknown
    1. Consider switching to formula while using Permethrin

XI. Efficacy

  1. Resistance increasing to 1% Permethrin
  2. Lice Treatment may require 5% Permethrin

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Related Studies

Cost: Medications

permethrin (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
PERMETHRIN 5% CREAM Generic $0.30 per gram