What are the uses of Crotamiton or Neomycin?

Uses of Crotamiton and Neomycin

Crotamiton is primarily used as an alternative treatment for scabies, while neomycin is used for suppression of intestinal bacteria before surgery, treatment of hepatic encephalopathy, and as a topical antibiotic, though both have significant limitations and are not first-line treatments for their respective indications. 1, 2

Crotamiton Uses

Scabies Treatment

• Crotamiton 10% is indicated as an alternative regimen for scabies when first-line treatments cannot be used 1
• Application protocol: Applied to the entire body from the neck down, nightly for 2 consecutive nights, and washed off 24 hours after the second application 1

Efficacy Limitations

• Not recommended for generalized pruritus of unknown origin (GPUO) due to lack of significant antipruritic effect compared to vehicle in randomized controlled trials 1
• Clinical studies show inferior efficacy compared to other scabicides:
  • Only 41.2-46.8% cure rate at 2-week follow-up 3, 4
  • 62.5-65% cure rate at 4-week follow-up even after repeated treatment 5, 4
  • Significantly less effective than permethrin (65% vs 85% cure rate) 5, 6

Neomycin Uses

FDA-Approved Indications 2

1. Suppression of intestinal bacteria:

   • Used as adjunctive therapy for preoperative bowel preparation
   • Often given concomitantly with erythromycin enteric-coated base

2. Hepatic encephalopathy (portal-systemic encephalopathy):

   • Reduces ammonia-forming bacteria in the intestinal tract
   • Decreases blood ammonia levels, resulting in neurologic improvement

Topical Applications

• Used in combination with other antibiotics in topical preparations 1
• Commonly found in products for treating skin infections and preventing infection in minor cuts, burns, and wounds
• Caution: Approximately 5-15% of patients with chronic external otitis may develop hypersensitivity to neomycin 1

Important Safety Considerations

Neomycin Warnings 2

• Systemic absorption can occur even with oral administration
• Serious risks include:
  • Neurotoxicity and ototoxicity (permanent bilateral auditory damage)
  • Nephrotoxicity (kidney damage)
  • Neuromuscular blockage and respiratory paralysis (rare)
• Higher risk in patients with:
  • Impaired renal function
  • Advanced age
  • Dehydration
  • Concurrent use of other aminoglycosides or nephrotoxic/neurotoxic drugs

Crotamiton Limitations

• British Association of Dermatologists explicitly recommends against using crotamiton cream for generalized pruritus of unknown origin (Strength of recommendation B; Level of evidence 1+) 1
• Should not be applied to the eyes or used for pediculosis of the eyelashes 1

Treatment Alternatives

For Scabies

• First-line treatments (more effective than crotamiton):
  • Permethrin cream (5%) - applied to all areas of the body from the neck down and washed off after 8-14 hours 1
  • Oral ivermectin - provides higher cure rates (87.5% vs 62.5%) at 4-week follow-up 4

For Bacterial Suppression

• Consider alternative antibiotics with fewer toxicity concerns when appropriate
• Carefully monitor renal function, hearing, and vestibular function when neomycin must be used

Special Populations

Pregnancy and Lactation

• Pregnant and lactating women with scabies should be treated with permethrin rather than crotamiton 1
• Neomycin should be used with caution in pregnancy due to potential risks

Elderly and Renal Impairment

• Neomycin poses higher risks in elderly patients and those with impaired renal function 2
• Careful monitoring of renal function and hearing is essential if neomycin must be used in these populations

Remember that both medications have been largely replaced by safer and more effective alternatives in modern clinical practice for most indications.