Opioid analogues

Q55 Loperamide is a synthetic opioid analogue that increases gut motility. Loperamide should be avoided in patients with active ulcerative colitis. 

Loperamide is an opioid analogue that binds to the opiate gut receptors, thereby decreasing intestinal motility and increasing transit time. Loperamide is contraindicated in patients with active ulcerative colitis and children under 4 years. It is used in the treatment of diarrhoea. 

As briefly reported the synthesis of an ideal analgesic asks for an improvement of both pharmacodynamic and in pharmacokinetic peculiarities. Sometimes if pharmacodynamic properties are improved, the pharmacokinetic characters can be still far from those of a perfect analgesic molecule. The quantities of opioids normally transported into the CNS can be low, and inadequate blood-brain barrier (BBB) permeation can be responsible for not optimized or for the different analgesic potencies among different opioid analogues. Consistently one major avenue of investigation involves the development of opioid analogues that penetrate the blood-brain-barrier (BBB). 

One major avenue of investigation in the field of opioid agonist and antagonist molecules involves the development of opioid analogues that penetrate the blood-brain-barrier (BBB) In fact inadequate blood-brain barrier (BBB) permeation can be responsible for low analgesic potencies. 

The SAR for p antagonists is relatively simple if one foouses just on marketed compounds. All of the marketed, rigid-structured opioid analogues that have the 3-phenolic group and an N-allyl,... 

Figure 4.6. Structure of the lipid-soluble synthetic opioid analogue fentanyl.

Substitution of Trp by D-Trp increased the potency of somatostatin (101). Most other substitutions, however, are deleterious to biological activity. Cychc octapeptide analogues of somatostatin retain high potency one of them, CTOP, is a potent mu-opioid antagonist. 

The replacement of the /V-methyl group on the nitrogen atom of the piperidine ring of morphine and analogues by aHyl, isopropyl, or methyl cyclopropyl, an isopropyl isostere, results in compounds which antagonize opioid responses, especially respiratory depression. Naloxone [465-65-6] C22H2 N04 (10... 

Opioid peptides, 17 (1980) 1 receptor antagonists, 35 (1998) 83 receptor-specific analogues, 28 (1991)... 

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