Neuronal nitric oxide synthase activity in rat urinary bladder detrusor: participation in M3 and M4 muscarinic receptor function

Drugs Currently Undergoing Preclinical or Clinical Trials for the Treatment of Overactive Bladder: A Review

Background

Overactive bladder (OAB) is a common clinical condition for which current drug treatment comprises drugs blocking the cholinergic nerve supply, or augmenting the adrenergic nerve supply, to the detrusor muscle of the urinary bladder. Current treatments have drawbacks, including lack of efficacy and the development of adverse effects in some patients. Hence, new and better drugs for treating OAB will be clinically useful.

Objective

This review is meant to provide information on drugs currently undergoing preclinical or clinical trials for the treatment of OAB published in journal articles or elsewhere.

Methods

The cited articles were retrieved from PubMed and Google Scholar from January 1, 1990, to December 31, 2021. The search terms used were contraction or contractility, detrusor, inhibition, isolated or in vitro, in vivo, overactive bladder, and relaxant effect or relaxation.

Results

There are 4 classes of new drugs under various stages of development for the treatment of OAB. These are drugs acting on the autonomic nerve supply to the detrusor muscle of the urinary bladder that include the anticholinergics tarafenacin and afacifenacin and the β₃ adrenoceptor agonists solabegron and ritobegron; drugs acting on ion channels in the detrusor muscle (eg, potassium channel openers and calcium channel blockers), drugs acting on cellular enzymes like phosphodiesterase-5 inhibitors and Rho kinase inhibitors, and drugs acting on miscellaneous targets (eg, pregabalin and trimetazidine).

Conclusions

Drugs currently used to treat OAB target only the cholinergic and adrenergic cellular signalling pathways. There are many other drugs under trial targeting other cellular pathways that may be useful for treating OAB. Their approval for clinical use might improve the treatment of patients with OAB. (Curr Ther Res Clin Exp. 2022; 83:XXX–XXX)

The effect of solifenacin on postvoid dribbling in women: results of a randomized, double-blind placebo-controlled trial

INTRODUCTION AND HYPOTHESIS

To determine the effectiveness of the muscarinic receptor antagonist solifenacin (VESIcare®) in the treatment of postvoid dribbling (PVD).

METHODS

We carried out a multicenter, 12-week, double-blind, randomized, placebo-controlled, parallel design study. Between 2012 and 2015, a total of 118 women (age 18-89 years) with PVD at least twice/weekly, were randomized to receive solifenacin (5 mg; n = 58) or placebo (n = 60) once daily. The primary outcome was the percentage reduction in PVD episodes. Secondary outcomes included the percentage of patients with ≥50% reduction in PVD episodes and changes in quality of life.

RESULTS

There were no differences in either the primary or secondary outcome variables. Subgroup analysis, based on those with more severe disease (>10 PVD episodes/week), showed a greater and significant percentage reduction in the frequency of PVD episodes per day (60.3% vs 32.1%; p = 0.035) and a higher percentage of patients showing ≥50% reduction in the frequency of PVD episodes with solifenacin (68.1% vs 45.8%; p = 0.0476). A significant solifenacin effect occurred at week 2 and continued through week 12 for the subgroup. For solifenacin, PVD reduction was the same for the entire cohort and subgroup, whereas for placebo, it was 10% lower in the subgroup, declining from 42% to 32%.

CONCLUSION

There were no differences in PVD outcomes between the solifenacin and placebo groups. Solifenacin may play a role in treating women with the most severe symptoms. Because of the powerful placebo response seen in this study, behavior-based interventions may be useful for treating PVD.

Diphenidol-related diamines as novel muscarinic M4 receptor antagonists

A series of hydrochloride derivatives 2a-9a and quaternary ammonium derivatives 3b-9b of diphenidol have been synthesized and characterized in receptor binding and cellular functional assays versus human muscarinic M(1)-M(5) receptors expressed in CHO cells. Compound 8b, a methiodide derivative with a bipiperidinyl moiety and a second diphenidol framework, showed a potent and selective M(4) activity as competitive antagonist. Moreover 8b, acting as an allosteric modulator, was able to retard the dissociation rate of [(3)H]-N-methylscopolamine from CHO-M(4) cell membranes exposed to atropine. Taken together, these data suggest that 8b might open new avenues to the discovery of novel multivalent antagonists for the muscarinic receptors.

Regulation of m1 muscarinic receptors and nNOS mRNA levels by autoantibodies from schizophrenic patients

In this paper we demonstrate that, circulating antibodies from schizophrenic patients interacting with cerebral M1 muscarinic acetylcholine receptors (M1 mAChRs), can act as an inducer of m1 mAChR-mRNA, and neuronal nitric oxide synthase (nNOS) mRNA gene expression of rat frontal cortex. The different signaling pathways involved in the autoantibody's actions, were characterized. As previously reported serum autoantibodies from schizophrenic patients reacted against neural cells surface inhibiting the binding of the specific mAChR radioligand to rat cerebral frontal cortex membrane. Moreover, by ELISA using M1 synthetic peptide (with identical aminoacid sequence to human M1 mAChR) as coating antigen we demonstrated the reactivity against the second extracellular loop of human cerebral M1 mAChR. The corresponding affinity-purified anti M1 peptide IgG (anti M1 peptide IgG) from schizophrenic patients by stimulation of M1 mAChR exerted an increase in m1 mAChR-mRNA and nNOS-mRNA levels, that significantly correlated with the accumulation of phosphoinositides (IPs) and activation of NOS (alpha = 0.05). All these effects were blunted by pirenzepine and mimicked the action of the authentic agonist. Concurrent analysis of the effects of nNOS, phospholipase C (PLC) and calcium/calmodulin (CaM) inhibition on both, m1 mAChR-mRNA and nNOS-mRNA levels, showing that antibody up-regulation mRNA level is under the control of endogenous nitric oxide (NO) signaling system. On the basis of our results, the activation of M1 mAChR by schizophrenic autoantibody appears to induce nNOS-mRNA expression and reciprocally, the activation of NOS up-regulates m1 mAChR gene expression. These results gave support to the participation of an autoimmune process in a particular group of chronic schizophrenic patients.