α1-Adrenoceptors and muscarinic receptors in voiding function – binding characteristics of therapeutic agents in relation to the pharmacokinetics

Authors

  • Shizuo Yamada,

    Corresponding author
    1. Department of Pharmacokinetics and Pharmacodynamics and Global Center of Excellence (COE) Program, School of Pharmaceutical Sciences, University of Shizuoka, Yada, Shizuoka 422-8526, Japan
      Prof. Shizuo Yamada, Department of Pharmacokinetics and Pharmacodynamics and Global Center of Excellence (COE) Program, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan.
      Tel.: +81 54 264 5631
      Fax: +81 54 264 5635
      E-mail: yamada@u-shizuoka-ken.ac.jp
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  • Yoshihiko Ito,

    1. Department of Pharmacokinetics and Pharmacodynamics and Global Center of Excellence (COE) Program, School of Pharmaceutical Sciences, University of Shizuoka, Yada, Shizuoka 422-8526, Japan
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  • Hideo Tsukada

    1. Central Research Laboratory, Hamamatsu Photonics KK, Hamamatsu, Shizuoka 434-8601, Japan
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Prof. Shizuo Yamada, Department of Pharmacokinetics and Pharmacodynamics and Global Center of Excellence (COE) Program, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan.
Tel.: +81 54 264 5631
Fax: +81 54 264 5635
E-mail: yamada@u-shizuoka-ken.ac.jp

Abstract

In vivo and ex vivo binding of α1-adrenoceptor and muscarinic receptors involved in voiding function is reviewed with therapeutic agents (α1-adrenoceptor antagonists: prazosin, tamsulosin and silodosin; and muscarinic receptor antagonists: oxybutynin, tolterodine, solifenacin, propiverine, imiafenacin and darifenacin) in lower urinary tract symptoms. This approach allows estimation of the inhibition of a well-characterized selective (standard) radioligand by unlabelled potential drugs or direct measurement of the distribution and receptor binding of a standard radioligand or radiolabelled form of a novel drug. In fact, these studies could be conducted in various tissues from animals pretreated with radioligands and/or unlabelled novel drugs, by conventional radioligand binding assay, radioactivity measurement, autoradiography and positron emission tomography. In vivo and ex vivo receptor binding with α1-adrenoceptor antagonists and muscarinic receptor antagonists have been proved to be useful in predicting the potency, organ selectivity and duration of action of drugs in relation to their pharmacokinetics. Such evaluations of drug–receptor binding reveal that adverse effects could be avoided by the use of new α1-adrenoceptor antagonists and muscarinic receptor antagonists for the treatment of lower urinary tract symptoms. Thus, the comparative analysis of α1-adrenoceptor and muscarinic receptor binding characteristics in the lower urinary tract and other tissues after systemic administration of therapeutic agents allows the rationale for their pharmacological characteristics from the integrated viewpoint of pharmacokinetics and pharmacodynamics. The current review emphasizes the usefulness of in vivo and ex vivo receptor binding in the discovery and development of novel drugs for the treatment of not only urinary dysfunction but also other disorders.

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