Effects of carvedilol on human prostate tissue contractility and stromal cell growth pointing to potential clinical implications.

BACKGROUND: Apart from antagonizing ß-adrenoceptors, carvedilol antagonizes vascular α1-adrenoceptors and activates G protein-independent signaling. Even though it is a commonly used antihypertensive and α1-adrenoceptors are essential for the treatment of voiding symptoms in benign prostatic hyperplasia, its actions in the human prostate are still unknown. Here, we examined carvedilol effects on contractions of human prostate tissues, and on stromal cell growth. METHODS: Contractions of prostate tissues from radical prostatectomy were induced by electric field stimulation (EFS) or α1-agonists. Growth-related functions were examined in cultured stromal cells. RESULTS: Concentration-response curves for phenylephrine, methoxamine and noradrenaline were right shifted by carvedilol (0.1-10 µM), around half a magnitude with 100 nM, half to one magnitude with 1 µM, and two magnitudes with 10 µM. Right shifts were reflected by increased EC50 values for agonists, with unchanged Emax values. EFS-induced contractions were reduced by 21-54% with 0.01-1 µM carvedilol, and by 94% by 10 µM. Colony numbers of stromal cells were increased by 500 nM, but reduced by 1-10 µM carvedilol, while all concentrations reduced colony size. Decreases in viability were time-dependent with 0.1-0.3 µM, but complete with 10 µM. Proliferation was slightly increased by 0.1-0.5 µM, but reduced with 1-10 µM. CONCLUSIONS: Carvedilol antagonizes α1-adrenoceptors in the human prostate, starting with concentrations in ranges of known plasma levels. In vitro, effect sizes resemble those of α1-blockers used for the treatment of voiding symptoms, which requires concentrations beyond plasma levels. Bidirectional and dynamic effects on the growth of stromal cells may be attributed to "biased agonism".

Potential side effects of currently available pharmacotherapies in male lower urinary tract symptoms suggestive of benign prostatic hyperplasia.

INTRODUCTION: The drug classes of α1-adrenoceptor antagonists, 5α-reductase inhibitors, and phosphodiesterase type 5 inhibitors are guideline-recommended treatments of lower urinary tract symptoms suggestive of benign prostatic hyperplasia; muscarinic receptor antagonists and ß3-adrenoceptor agonists are also recommended if storage symptoms are insufficiently addressed with one of the other three drug classes. AREAS COVERED: We provide a narrative review (no formalized literature searches performed) of the tolerability of these drug classes with emphasis on the more recently introduced medications, on combination treatment, and on more lately emerging risks. EXPERT OPINION/COMMENTARY: The tolerability profiles are distinct between drug classes but, with few exceptions, similar within a drug class. Within a drug, formulations with longer duration of action tend to have better tolerability. Efficacy gains using combination treatment at least partly come at a cost of lesser tolerability. Greater susceptibility to experience adverse events based on age, comorbidities, and comedications appears conceptually important but remains under-investigated in this therapeutic area.

Several classes of medicines are available to treat male lower urinary tract symptoms that are believed to result from an enlarged prostate. These include α₁-adrenoceptor antagonists (α-blockers), 5α-reductase inhibitors (ARI), and phosphodiesterase type 5 inhibitors (PDEI); muscarinic receptor antagonists and ß₃-adrenoceptor agonists are additionally used in men that have persisting storage symptoms upon treatment with the former three drug classes. Each drug class has a distinct tolerability profile. Within a drug class, medicines with a longer duration of action, either intrinsically or due to specific drug formulations, tend to have better tolerability. Men with greater age, comorbidities, and comedications may be at greater risk of experiencing side effects when medically treating their lower urinary tract symptoms. While combination of members of multiple drug classes may increase efficacy, this often comes at the price of experiencing more side effects. The relative benefit/risk ratio needs to be individually analyzed in each patient.

Cognitive and mood side effects of lower urinary tract medication.

Introduction: Muscarinic receptor antagonists, 5α-reductase inhibitors and α1-adrenoceptor antagonists are frequently used drug classes for the treatment of lower urinary tract symptoms including those of overactive bladder syndrome and benign prostatic enlargement/benign prostatic obstruction. Areas covered: The authors review the evidence for adverse effects of these drug classes on cognitive function, mood and other functions of the central nervous system and discuss such effects against the evidence for mechanistic plausibility. Expert opinion: Muscarinic antagonists carry a risk for impaired cognition and other brain functions that differs quantitatively between compounds, being highest with oral formulations of oxybutynin. 5□-Reductase inhibitors can cause depressive symptoms even at low doses and starting several months after discontinuation of treatment. The evidence for α1-adrenoceptor antagonists and specifically tamsulosin to cause dementia is controversial and lacks mechanistic plausibility. We recommend that physicians treating patients with lower urinary tract symptoms carefully monitor mental status prior to prescribing and periodically thereafter.