Which 2 drugs used to treat overactive bladder are selective for M3 receptors specifically?

Darifenacin and Solifenacin are indeed selective for M3 muscarinic receptors, which are primarily responsible for mediating bladder detrusor muscle contraction leading to urination. The M3 receptor selectivity of these drugs is significant as it allows for effective management of overactive bladder symptoms while minimizing effects on other muscarinic receptor subtypes, such as M1 and M2, which are involved in central nervous system and other peripheral functions. This selectivity helps reduce the potential for side effects like dry mouth and constipation that can occur with less selective anticholinergic medications.

In contrast, the other choices consist of drugs that either have broader activity across multiple muscarinic receptor subtypes or are not typically used for treating overactive bladder. For example, oxybutynin and fesoterodine are generally not as selective for M3 as darifenacin and solifenacin. Tolterodine and trospium also exhibit varying degrees of selectivity but do not target M3 receptors as specifically as darifenacin and solifenacin. Lastly, benztropine and trihexyphenidyl are primarily used as antiparkinsonian agents rather than for treating overactive bladder, underscoring the specificity of the correct