Opioid receptor antagonist

Group of substances that act as competitive antagonists of the opioid recept ors without exerting an agonistic effect on the receptor. They have the highest affinity for u-, an intermediate affinity for к- and the lowest affinity for δ-receptors (see below opioid receptors). Opioid receptor antagonists displace the opioid or opiate (e.g., heroin, codeine). Tricyclic antidepressants potentiate the analgesic effect of opioid receptor antagonists.

Naloxone and naltrexone are competitive antagonists. They are derived from the morphine derivative oxymorphone. A new substance that cannot cross the blood-brain barrier is methylnaltrexone.

• Naloxone (intravenous application)
• Naltrexone (peroral application)

• Opioid intoxication
• Respiratory depression due to morphine analgesics
• Confirmation of absence of opioid dependence in severe drug dependence
• Differential diagnosis of toxic coma
• Oral pain therapy: Naloxone is used in fixed combination with tilidine (1.0:1.25mg ratio) or oxycodone (1:2mg ratio).

Other Indications: Low-dose naltrexone (LDN) has been successfully studied as an immunomodulatory and anti-inflammatory therapy in a variety of conditions, including Crohn's disease, fibromyalgia, major depression, chronic regional pain syndrome, Charcot-Marie-Tooth, and multiple sclerosis.

Dermatological indications: Improvements have been seen in dermatological conditions such as systemic sclerosis, Hailey-Hailey disease, lichen planus follicularis , and guttate psoriasis with low-dose naltrexone. Naltrexone affects inflammation, cell adhesion, and keratinocyte proliferation and migration. It is believed that naltrexone may be effective in the treatment of pruritus and a variety of inflammatory and acantholytic skin diseases (Lee B et al. 2019).

1. Jaros J et al (2019) Low dose naltrexone in dermatology. J Drugs Dermatol 18:235-238.
2. Katakami N et al. (2017) Randomized phase III and extension studies of naldemedine in patients with opioid-induced constipation and cancer. J Clin Oncol 35(34):3859-3866
3. Lee B et al (2019) The uses of naltrexone in dermatologic conditions. J Am Acad Dermatol 80:1746-1752.
4. Stein C (2019) Pain inhibition by opioids - new concepts. Pain 33:295-302
5. Ueberall MA et al (2016) Quality of life under oxycodone/naloxone, oxycodone, or morphine treatment for chronic low back pain in routine clinical practice. Int J Gen Med 9:39-51