1421-28-9

Dihydromorphone was prepared from morphine in high yield, excellent purity, and low residual metal content. The key steps used palladium on porous glass and a modified Oppenauer oxidation, or Wilkinson's catalyst. Georg Thieme Verlag Stuttgart ? New York.

(-)-N-Phenethyl analogs of optically pure N-norhydromorphone were synthesized and pharmacologically evaluated in several in vitro assays (opioid receptor binding, stimulation of [35S]GTPγS binding, forskolin-induced cAMP accumulation assay, and MOR-mediated β-arrestin recruitment assays). "Body"and "tail"interactions with opioid receptors (a subset of Portoghese's message-address theory) were used for molecular modeling and simulations, where the "address"can be considered the "body"of the hydromorphone molecule and the "message"delivered by the substituent (tail) on the aromatic ring of the N-phenethyl moiety. One compound, N-p-chlorophenethynorhydromorphone ((7aR,12bS)-3-(4-chlorophenethyl)-9-hydroxy-2,3,4,4a,5,6-hexahydro- 1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7(7aH)-one, 2i), was found to have nanomolar binding affinity at MOR and DOR. It was a potent partial agonist at MOR and a full potent agonist at DOR with a δ/μ potency ratio of 1.2 in the ([35S]GTPγS) assay. Bifunctional opioids that interact with MOR and DOR, the latter as agonists or antagonists, have been reported to have fewer sideeffects than MOR agonists. The p-chlorophenethyl compound 2i was evaluated for its effect on respiration in both mice and squirrel monkeys. Compound 2i did not depress respiration (using normal air) in mice or squirrel monkeys. However, under conditions of hypercapnia (using air mixed with 5% CO2), respiration was depressed in squirrel monkeys.

The oxidative metabolism of dihydrocodeine to nordihydrocodeine and dihydromorphine was studied in liver microsomes of female Dark-Agouti (cytochrome P450 2D1 (CYP2D1) deficient) and Sprague-Dawley rats. Evaluation of microsomal metabolism in these two rat strains is a useful in-vitro model to test possible substrates of polymorphic human cytochrome P450 2D6 (CYP2D6). Nordihydrocodeine formation rates were similar in both strains. Analysis of the Michaelis-Menten kinetics of dihydromorphine formation showed a significant difference (P -1 g-1) and intrinsic clearance (0.986; 19.5 mL min-1 g-1). In Sprague-Dawley liver microsomes, dihydromorphine formation was suppressed by the CYP2D1 inhibitors, quinine and quinidine, at concentrations which had no effect on nordihydrocodeine formation. These in-vitro findings indicate that in rat liver microsomes the cytochrome P450 system is involved in dihydrocodeine metabolism to dihydromorphine and nordihydrocodeine and that CYP2D1 is involved in the O-demethylation to dihydromorphine but not the N-demethylation to nordihydrocodeine. The results of this study are in agreement with recent in-vivo studies of dihydrocodeine metabolism in man which indicate CYP2D6 is the predominant enzyme catalysing dihydromorphine formation.