7,8-Dihydro-5H-1,6-Naphthyridines for M4 Allosteric Selectivity
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Solution Overview
Problem
Current treatments for neurological and psychiatric disorders associated with muscarinic acetylcholine receptor dysfunction, such as schizophrenia, are limited by the lack of highly selective activators for the M4 subtype, leading to adverse effects due to activation of peripheral receptors, and existing allosteric modulators have not been effective.
Innovation Solution
Development of 7,8-dihydro-5H-1,6-naphthyridine derivatives that act as positive allosteric modulators of the muscarinic acetylcholine receptor M4, binding to a distinct allosteric site to enhance receptor activity without activating the orthosteric site, thereby reducing peripheral side effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AChE inhibitors are used to increase acetylcholine levels, then cognitive deficits in Alzheimer's disease are improved, but cholinergic side effects such as abdominal cramps, nausea, vomiting, and diarrhea occur
Solution Approach 1:
The patent applies local quality by targeting a specific receptor subtype (M4) rather than all muscarinic receptors. The compound provides selective activation of M4 receptors in the brain, which are specifically involved in cognitive processing, while avoiding activation of peripheral M2 and M3 receptors that cause gastrointestinal side effects. This selective targeting resolves the contradiction by improving therapeutic efficacy through focused action while minimizing harmful side effects.
Solution Approach 2:
The patent segments the muscarinic acetylcholine receptor system into different subtypes (M1-M5) with distinct functions. By developing a selective M4 agonist, the invention isolates and activates only the subtype relevant for cognitive function, separating the beneficial cognitive effects from the harmful peripheral effects mediated by other subtypes. This segmentation allows independent optimization of therapeutic benefit without compromising safety.
2Reliability
If AChE inhibitors are used to treat cognitive deficits, then acetylcholine levels are increased, but hepatotoxicity with elevated liver transaminases occurs
Solution Approach 1:
The patent employs local quality by directing pharmacological action specifically to M4 receptors in the central nervous system rather than systemically increasing acetylcholine through AChE inhibition. This localized approach at the receptor level in the brain avoids the hepatic metabolism burden and toxic effects associated with systemic AChE inhibitor treatment, thereby maintaining therapeutic efficacy while eliminating hepatotoxicity.
3Reliability
If non-selective mAChR agonists are used to activate muscarinic receptors, then central cholinergic function is enhanced, but peripheral side effects are induced through activation of peripheral mAChRs
Solution Approach 1:
The patent implements local quality by creating a compound with high selectivity for M4 receptors over other muscarinic subtypes. The chemical structure and binding characteristics are optimized to preferentially activate M4 receptors in the brain, which mediate cognitive functions, while having minimal affinity for peripheral M2 and M3 receptors. This selective local activation resolves the contradiction by achieving central cholinergic enhancement without triggering peripheral side effects.
Solution Approach 2:
The patent segments the muscarinic receptor activation process by targeting a specific subset (M4) rather than activating all subtypes. This segmentation allows the compound to produce central cognitive benefits through M4 activation while leaving peripheral receptors unactivated, thereby preventing peripheral side effects and improving the safety profile.
4Reliability
If attempts are made to develop highly selective M4 agonists, then therapeutic selectivity is improved, but compound development becomes difficult due to inability to achieve high selectivity
Solution Approach 1:
The patent uses an intermediary approach by identifying and targeting the allosteric site on the M4 receptor rather than the orthosteric acetylcholine binding site. The allosteric site provides a unique binding pocket that is less conserved across receptor subtypes, serving as an intermediary target that enables high selectivity. The compound binds to this allosteric site to modulate M4 receptor function, achieving the desired selectivity that was previously unattainable through orthosteric agonists.
Solution Approach 2:
The patent applies parameter changes by shifting the binding site from the orthosteric site to the allosteric site, fundamentally changing the pharmacological parameter of receptor interaction. This site change enables discrimination between M4 and other muscarinic subtypes based on differences in allosteric site structure. The chemical compounds are designed to exploit this structural difference, achieving high M4 selectivity that was not possible with orthosteric agonists.
Data Source
AI summary
The present invention relates to 7,8-dihydro-5H-1,6-naphthyridine derivatives of formula (I) The present compounds are positive allosteric modulators of the muscarinic acetylcholine receptor M4 (mAChR M4) for use in treating neurological and psychiatric disorders associated with muscarinic acetylcholine receptor dysfunction. An exemplary compound is e.g. compound 1 Data on the activity of exemplary compounds in an mAChR M4 cell-based assay is provided.15-methyl-6- (3-pyrrolidin- 1-1-7,8- dihydro-5H-1,6- naphtbyridin- 6-yl)pyridine- 3-carbonitrile320.2