PT - JOURNAL ARTICLE AU - FRED W. OBERST TI - RELATIONSHIP OF THE CHEMICAL STRUCTURE OF MORPHINE DERIVATIVES TO THEIR URINARY EXCRETION IN FREE AND BOUND FORMS DP - 1941 Dec 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 401--404 VI - 73 IP - 4 4099 - http://jpet.aspetjournals.org/content/73/4/401.short 4100 - http://jpet.aspetjournals.org/content/73/4/401.full SO - J Pharmacol Exp Ther1941 Dec 01; 73 AB - Morphine, alpha-isomorphine, methyl morphine (Codeine), and dihydroheterocodeine are excreted in both free and bound forms. Diacetylmorphine (Heroin) is excreted as morphine in both forms. Dihydrocodeine and dihydroisocodeine are excreted mainly in the free form, only small amounts being bound. Dihydrocodeine methyl ether is excreted only in the free form. These results indicate that conjugation takes place on either the phenolic or the alcoholic hydroxide. Since the glucuronic acid concentration in urine increases proportionately with increasing dosages of morphine, the substance bound with morphine and certain of its derivatives is thought to be largely glucuronic acid or its lactone form, glucurone.