scabies
SCABIES
Scabies is a contagious disease caused by the mite Sarcoptes scabiei var hominis.
The affected individual usually complains of having a highly pruritic rash that occurs at night.
It occurs more often in children <15 years of age, sexually active young adults, the immunocompromised and in persons living in crowded living conditions (eg nursing homes, military barracks).
Transmission is typically by direct skin contact with an infected person and in adults, sexual transmission is common.

Pharmacotherapy

Keratolytics (Topical)

  • The removal of crust & scales w/ keratolytics is necessary for scabicide penetration of crusted scabies

Ivermectin (Oral)

  • Effective treatment option for scabies patients unresponsive to 1st-line/2nd-line treatment
  • Combination therapy w/ topical scabicides it is considered to be the best option for crusted scabies
  • May have a role in the treatment of refractory infestations & immunocompromised patients, or when administration of head-to-toe topical therapy would be difficult
    • May also be used in scabies epidemics in institutions
  • Actions: Interrupts GABA-induced neurotransmission of many parasites

Scabicides (Topical)

Benzyl Benzoate

  • Effective in the management of Permethrin-resistant crusted scabies
  • Different treatment regimens have been used but no comparative data have been published
  • May be used alone or in combination w/ Sulfiram
  • Maybe used w/ Ivermectin for patients w/ relapses after single treatment of Ivermectin

Crotamiton

  • May be useful for the treatment of nodule scabies in children but may require up to 5 days of treatment
  • May be used for symptomatic relief from pruritus but there is conflicting evidence of its efficacy
  • Appears to be less effective as a scabicide than Permethrin & Lindane

Malathion

  • Overnight application of 5% aqueous preparation is an effective treatment option

Lindane (Gamma Benzene Hexachloride)

  • When used properly, it is an effective scabicide
    • 1% formulation is usually effective after a single six-hr treatment
  • Lindane-resistant scabies has been noted in North, Central & South America & in Asia

Permethrin

  • Considered 1st-line treatment in countries where 5% Permethrin is available
  • Has been shown to be as effective as Lindane & more effective than Crotamiton
  • Has low toxicity

Sulfur

  • The oldest known treatment for scabies
  • Safe & effective, but requires application on 3 consecutive days
  • Safety & efficacy in children <12 yr have not been established
  • Reproduction studies have not been conducted

Sulfiram

  • May also be used to treat human scabies
    • Soap-containing monosulfiram have been used in the past as a prophylaxis for scabies

Other therapies

  • Nodular scabies may be treated w/ corticosteroids after completed scabicide therapy
  • Oral antihistamines may be given to help alleviate pruritus
  • Secondary infections should be treated w/ appropriate antibiotics
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