|Trade names||Movantik, Moventig|
|Elimination half-life||6–11 h|
|Excretion||Feces (68%), urine (16%)|
|CompTox Dashboard (EPA)|
|Chemical and physical data|
|Molar mass||651.785 g/mol g·mol−1|
|3D model (JSmol)|
Naloxegol (INN; PEGylated naloxol; trade names Movantik and Moventig) is a peripherally acting μ-opioid receptor antagonist developed by AstraZeneca, licensed from Nektar Therapeutics, for the treatment of opioid-induced constipation. It was approved in 2014 in adult patients with chronic, non-cancer pain. Doses of 25 mg were found safe and well tolerated for 52 weeks. When given concomitantly with opioid analgesics, naloxegol reduced constipation-related side effects, while maintaining comparable levels of analgesia.
The most common side effects are abdominal pain, diarrhea, nausea, flatulence, vomiting and headache. As a pure opioid antagonist Naloxegol has no potential for abuse.
Naloxegol was previously a Schedule II drug in the United States because of its chemical similarity to opium alkaloids, but was recently reclassified as a prescription drug after the FDA concluded that the impermeability of the blood-brain barrier to this compound made it non-habit-forming, and so without the potential for abuse—specifically, naloxegol was officially decontrolled on 23 January 2015.
Naloxegol is indicated for the treatment of opioid-induced constipation (OIC) in patients with chronic non-cancer pain. It is recommended that any maintenance laxative be discontinued before starting naloxegol or be held for at-least 3 days. Naloxegol should be taken on an empty stomach at least two hours after the last meal.
Naloxegol inhibits opioid binding in μ-opioid receptors in the gastrointestinal tract, thus decreasing the constipating effects (slowing of gastrointestinal motility and transit, hypertonicity, increased fluid reabsorption) associated with opioids.
Chemically, naloxegol is a pegylated (polyethylene glycol-modified) derivative of α-naloxol. Specifically, the 6-α-hydroxyl group of α-naloxol is connected via an ether linkage to the free hydroxyl group of a monomethoxy-terminated n=7 oligomer of PEG, shown extending at the lower left of the molecule image at right. The "n=7" defines the number of two-carbon ethylenes, and so the chain length, of the attached PEG chain, and the "monomethoxy" indicates that the terminal hydroxyl group of the PEG is "capped" with a methyl group. The pegylation of the 6-α-hydroxyl side chain of naloxol prevents the drug from crossing the blood-brain barrier (BBB). As such, it can be considered the antithesis of the peripherally-acting opiate loperamide which is utilized as an opiate-targeting anti-diarrheal agent that does not cause traditional opiate side-effects due to its inability to accumulate in the central nervous system in normal subjects.