Morphine phenazocine

Many benzomorphan derivatives with morphine-like potencies or better have a low physical dependence capacity (PDC) in monkeys especially potent members, however, such as phenazocine and the /3-isomers (Table 5.2, Nos. 8 and 16) have high to intermediate PDC properties [5, 63, 68]. Unusual results have been reported. for the enantiomorphs of a-(X) (R = Me, R = = Et) the... 

The most known narcotics are the opium alkaloids such as morphine, codeine, thebaine, papaverine, noscapine and their derivatives and modified compounds such as nalmorphine, apomorphine, apomopholcodine, dihydrocodeine, hydro-morphone and heroine, also known as diamorphine. Synthetic narcotics share the structural skeleton of morphine and include dextromethorphan, pentazocine, phenazocine meperidine (pethidine), phentanyl, anfentaitil, remifentalin, methadone, dextropropoxyphene, levoproxyphene, dipipanone, dextromoramide, meptazinol and tramadol. Thebaine derivatives are also modified narcotics and include oxycodone, oxymorphone, etorphine, buprenorphine, nalbuphine, naloxone or naltrexone. Narcotics can be semi-synthesized or totally synthesized from the morphine and thebaine model. The compounds serve various purposes in clinical practise. 

Phenazocine (Prinadol ), 1,2,3,4,5,6-hexahydro-8-hydroxy-6,11-dimethyl- 3-phenethyl-2,6-methano-3-benzazocine hydrobromide, was synthesized at the National Institutes of Health in a search for new analgesics with low addictive liability. Addiction to phenazocine develops more slowly and is less intense when dosages equivalent to morphine are administered chronically for 30 d. The incidence of side effects (respiratory depression, hypotension, and nausea and vomiting) are less with phenazocine than with morphine. 

Drugs in this therapeutic group include morphine, heroin, pethidine, methadone, codeine, dihydrocodeine, dextropropoxyphene, pentazocine, phenazocine, levorphanol and buprenorphine. The principal antagonists in clinical use are naloxone and naltrexone (see Figure 15.3). 

The replacement of N-methyl by N-phenethyl in morphine increases analgesic potency by up to sixfold.(73) The corresponding change from meta-zocine (122) to phenazocine (123)<74) results in a similar increase in potency in both animal models and humans. Clinically, phenazocine (Narphen) is... 

Toxicity. The estimated minimum lethal dose is 0.2 g. Phenazocine is addictive although tolerance develops more slowly and to a lesser extent than with morphine. 

Pain due to spasm of visceral smooth muscle, e.g. biliary, renal colic, when severe, requires a substantial dose of morphine, pethidine or buprenorphine. These drugs themselves cause spasm of visceral smooth muscle and so have a simultaneous action tending to increase the pain. Phenazocine and buprenorphine are less liable to cause spasm. An antimuscarinic drug such as atropine or hyoscine may be given simultaneously to antagonise this effect. 

Wilson, T.D. Recent advances in HPLC analysis of analgesics. J.Liq.Chromatogr., 1986, 9, 2309-2410 [also antipyrine, aspirin, buprenorphine, butorphanol, codeine, cyclazocine, diamorphine, dihydrocodeine, etorphine, fentanyl, heroin, hydrocodone, hydromorphone, ibuprofen, LAAM, levorphanol, meperidine, methadone, morphine, nalbuphine, naproxen, oxycodone, ox nnorphone, pentazocine, phenacetin, phenazocine, phenylbutazone, propoxyphene, salicylamide, salicylic acid, zomepirac]... 

---