Chronic itching is a common problem that can come from many different sources like dermatitis, psoriasis, or as a side effect of chronic opioid use. Treatment often includes corticosteroids or antihistamines, but these can be unsatisfactory in some patients who will then need a more individualized treatment. Options that can be compounded would include a topical naltrexone cream, topical immunomodulators, urea creams, topical anesthetics, and many more.
https://www.ncbi.nlm.nih.gov/pubmed?term=20426711
Treatment of pruritus with topically applied opiate receptor antagonist.
https://www.ncbi.nlm.nih.gov/pubmed?term=17320241