Functional uroselectivity.

Alpha1-adrenoceptors mediating sympathetic tone to smooth muscle cells are located within the prostatic tissue, bladder base and in the proximal urethra, but are also widely distributed within a large number of tissues, especially the vascular beds and the central nervous system. Compounds clinically used in the symptomatic treatment of benign prostatic hyperplasia must therefore exhibit functional uroselectivity. This means that they should preferentially act on the lower urinary tract rather than the vasculature or central nervous system. Few clinically used alpha1-adrenoceptor antagonists show selectivity for the alpha1a/A-adrenoceptor subtype, whereas most of them have similar affinities for the three cloned subtypes (alpha1a-, alpha1b- and alpha1d-adrenoceptors). Recent data from in vitro studies assessing pharmacological uroselectivity and from in vivo models evaluating functional uroselectivity challenged the relevance of the affinity or the selectivity for a known alpha1-adrenoceptor subtype in predicting functional uroselectivity. They suggest instead that another subtype, like the alpha1L-adrenoceptor, might be functionally involved. In conclusion, the actual state of knowledge on alpha1-adrenoceptor subtype distribution and function, does not support a role of pharmacological uroselectivity in predicting functional uroselectivity. Furthermore, functional uroselectivity can be achieved in the absence of selectivity for the alpha1-adrenoceptor subtypes described so far.