Morphine-6-glucuronide (M6G), a pharmacologically active metabolite of morphine, is suitable for the treatment of post-operative pain. Gold standard for treating moderate to severe pain after surgery is currently morphine. The applicability of morphine is often limited by unpleasant side effects, especially nausea and vomiting. M6G could significantly less likely induce nausea, vomi­ting, or inhibition of respiratory depression with equal efficacy.


PAION performed a meta-analysis of the combined clinical data of 769 patients which confirmed a morphine-like analgesic effect and also showed a significant reduction of nausea and vomiting compared with patients who received morphine.


Modelling analyses were conducted to simulate dose response relationships and pharma­codynamic effects. The results support the product profile of M6G, both in terms of its analgesic properties and side-effect profile. In addition, the previously observed longer duration of action of M6G compared to morphine could be reproduced. Based on this model, PAION believes that even at increased doses M6G may be better tolerated than equianalgesic doses of morphine.


Due to the focus of the available resources on anesthesia and the restructuring at that time, the clinical development of M6G was discontinued by PAION in 2011. In September 2014, this project was licensed to Yichang Humanwell for the Chinese market. Yichang Humanwell recei­ves an exclusive license under PAION’s know-how regarding M6G for the development, manufac­ture and commercialization in the People’s Republic of China. By concluding the license, PAION receives payments totaling EUR 1.6 million. Additional license fees were not agreed.