SELECTED ARTICLES FROM THE RECENT LITERATURE 2004

12/17/04

Itch and its treatment

Summary
Background - Chronic itch is a common and sometimes quite distressing symptoms that may impact significantly on the quality of life. There has been recent increasing investigation of the pathophysiology of itching and approaches to control it.

Findings - The subject of itch and its management was reviewed by Greaves and Khalife of the St. Thomas Hospital in London, UK. They stressed that itch is a complex manifestation which can be of several types: 1) Pruritogenic - itch stimulus in inflammatory skin lesions; 2) Neuropathic - due to certain diseases of neural pathways (e.g.,- some neuropathies); 3) Neurogenic - on a central basis due to altered balance of activation/inhibitory pathways or release of pruritogenic chemicals (e.g. - opioid peptides in cholestasis); 4) Psychogenic . In some conditions (e.g. - atopic dermatitis) more than one type of itching mechanism may be present.

The efficacy of treatment of itch depends on the cause of the itch. 1) In urticaria, H1 antihistamines are often effective since histamine is the major pruritogenic factor; 2) in atopic dermatitis topical corticosteroid therapy often suppresses that itch; 3) in neurogenic or neuropathic itch, H1 antihistamines and topical steroids are generally not effective. One can try broad-based ultraviolet B treatment. If this is not sufficient, try doxepin, a tricyclic compound with potent antihistamine, anti depressant actions. Doxepin appear to suppress itch by non-specific suppression of itch perception. It is best used h.s. in doses of 10-50 mg starting at the low dose and increasing as needed and tolerated. Sedation, dry mouth, and p450 enzyme pathway drug interactions must be watched for. Withdrawal of doxepin should be gradual.

Opioid mu receptor antagonists such as naltrexone (25-50 mg once daily in adults) often suppress the itch of cholestasis conditions and chronic renal insufficiency. They should not be used in patients requiring opioid treatment and/or have chronic liver disease. Nalbuphine (a combination K-receptor agonist and mu receptor antagonist) may be more effective than naltrexone alone.

Paroxetine, a selective serotonin uptake inhibitor, can be effective in suppressing itch associated with malignancies. If nausea occurs use with cisapride.

Reference
Int Arch Allergy & Immunol 2004;135:166-72

Editor's Comments
Over the years, I have found chronic itch a frequently difficult management problem. In a few individuals, the itch was so severe and poorly controlled that it almost drove individuals to thoughts of suicide.

These thoughtful comments by leading investigators of pruritic skin diseases are well worth consideration as a basis for more effective treatment of itching. Remember, not all itching is helped by antihistamine therapy!

 

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