Antagonist-receptor interaction

Figure 3. Details of the interaction between the antagonist 5-methylurapidil and the conserved amino acids of the three AR subtypes, postulated to make the major contribution to antagonist-receptor interaction. The green color labels for favourable interactions while the red color labels for un vourable interactions.

Hruby, V.J. (1987) Implications of the X-ray structure of deamino-oxytocin to agonist/antagonist-receptor interactions. Trends Pharmacol. Sci. 8 336-339. 

It is obvious that strenuous efforts have been invested in the research of 5-HT receptors and, in particular, in the development of receptor-selective agonists and antagonists. All this has been done in the hope that it might be possible to control a specific switch in the brain that governs a particular aspect of 5-HT function and which would be beneficial therapeutically. A further ambition is that, by avoiding activation of other 5-HT receptors, the risk of any unwanted side-effects would be eliminated. Of course, it is equally possible that reduction in non-specific receptor interactions could actually unmask some side-effects. 

The pharmacological properties of the cloned opiate receptors are similar to the characteristics of the endogenously expressed receptors [9, 36, 45]. The binding of opiates to the cloned receptors is stereoselective and the antagonist naloxone interacts with all three of the cloned receptors, although naloxone had much lower af-... 

Drug-receptor interactions, and ability of 5-HT antagonists to attenuate DS properties of hallucinogens, 87-88... 

A 5-(methylthio)methyl-substituted derivative (cis-28) of ( + )-3-PPP has been reported [91]. The background to the study was the structural similarity between pergolide (29) and (cis-28). However, the biological testing of (cis-28) showed that it is inactive in vivo (GBL model), while an in vitro assay (inhibition of tyrosine hydroxylation) showed (cis-28) to be equipotent to racemic 3-PPP itself. These results indicate that the steric bulk in (cis-28) is not compatible with potent DA receptor interaction. However, since compound (cis-28) was not resolved, there is a possibility that one or both of the enantiomers of (cis-28) might have antagonistic properties [89]. 

H2-antagonists competitively interact with the H2-receptor. They are very specific for the H2-sub-type of the histamine receptor. 

Antagonist Receptor Antagonist- No receptor response interaction... 

Fig. 1.5.1 Drug-receptor interaction The agonist completely fits (interact) with the receptor site to produce a pharmacological response and antagonist only partially fit with the receptor site and is unable to produce any pharmacological response, and also prevents the agonist from combining with the receptors.

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