What is Lotrexone (naltrexone)?

What is Lotrexone?

Lotrexone is a topical analgesic product for external use only, indicated for temporary relief of minor muscle and joint aches—it is NOT the same as naltrexone, which is an oral/injectable opioid antagonist used for substance use disorders. 1

Critical Distinction

There appears to be confusion in your question. Based on FDA labeling, Lotrexone (topical) and naltrexone (oral/injectable) are completely different medications:

Lotrexone (Topical Product)

• Indication: Temporary relief of minor aches and pains of muscles and joints associated with arthritis, backache, strains, sprains, muscle soreness and stiffness 1
• Route: External use only—applied to intact skin 1
• Key restrictions:
  • Do NOT use on wounds or damaged skin
  • Do NOT use in children under 12 years without consulting a doctor
  • Avoid eyes and mucous membranes
  • Do not use with heating devices or cover tightly 1

Naltrexone (Systemic Medication)

If you meant naltrexone (not "Lotrexone"), this is an entirely different drug:

• Mechanism: Opioid receptor antagonist (blocks mu and kappa opioid receptors) 2, 3
• FDA-approved indications:
  • Opioid use disorder treatment
  • Alcohol use disorder treatment 4, 5, 6
• Formulations:
  • Oral tablets (standard dose 50-150 mg daily)
  • Extended-release injectable (monthly)
  • Low-dose compounded (1-5 mg, off-label use) 7, 2, 8

Naltrexone works by competitively blocking opioid receptors, preventing euphoric effects of opioids and reducing alcohol cravings 4, 5. At low doses (1-5 mg), it acts through different mechanisms including glial modulation and anti-inflammatory effects via Toll-like receptor 4 antagonism 2, 8.

Common Pitfall

Do not confuse these two products. If prescribing for substance use disorder or chronic pain conditions, you need naltrexone (systemic), not Lotrexone (topical analgesic). The topical product has no role in addiction medicine or systemic pain management.