G allele (A118G) are very poor responders to morphine, and have to have higher doses with the drug to relieve pain. Also, morphine and its metabolites need to cross the BBB and penetrate the CNS to carry out their activity: it was shown that suffering reduction variability, in cancer https://whyshouldiuseconolidine65319.blogzet.com/not-known-factual-statements-about-proleviate-natures-morphine-43278287