Rizmoic is the only oral drug from the PAMORA class (peripherally acting mu-opioid receptor antagonists) available on the Polish market. The active ingredient of the drug is naldemedine, available in 200 μg tablets.

The drug is indicated and recommended for the treatment of post-opioid gastrointestinal disorders and opioid-induced constipation.

Naldemedine is an antagonist of opioid binding to mu, delta, and kappa-opioid receptors.
Naldemedine is a peripheral antagonist of mu-opioid receptors in tissues such as the stomach and intestines, reducing the effect of opioids on constipation without affecting the opioids’ effects on the central nervous system (CNS).

Naldemedine is a derivative of naltrexone, with an added side chain that increases the molecular mass and polar surface properties of the molecule, thus reducing its ability to cross the blood-brain barrier.

Additionally, naldemedine is a substrate of P-glycoprotein, an efflux transporter, which can further reduce the penetration of naldemedine into the CNS. As a result, naldemedine is expected to prevent opioid-induced constipation without inhibiting the opioid-related analgesic effect in the CNS.
Rizmoic is included in the list of reimbursed drugs for the treatment of “opioid-induced constipation in adult cancer patients, previously unsuccessfully treated with laxatives, and not using another opioid antagonist, either alone or in combination,” with no cost*.

Rizmoic is also included in the list of free medications for seniors over 65.

* According to the decree of the Minister of Health regarding the list of reimbursable drugs, foods for special medical purposes, and medical devices, effective from April 1, 2024.