Tamsulosin MR and OCAS (modified release and oral controlled absorption system): current therapeutic uses

QSAR studies on a number of pyrrolidin-2-one antiarrhythmic arylpiperazinyls

The activity of a number of 1-[3-(4-arylpiperazin-1-yl)propyl]pyrrolidin-2-one antiarrhythmic (AA) agents was described using the quantitative structure–activity relationship model by applying it to 33 compounds. The molecular descriptors of the AA activity were obtained by quantum chemical calculations combined with molecular modeling calculations. The resulting model explains up to 91% of the variance and it was successfully validated by four tests (LOO, LMO, external test, and Y-scrambling test). Statistical analysis shows that the AA activity of the studied compounds depends mainly on the PCR and JGI4 descriptors.

Structure-Activity Relationship Studies of a Number of α1 -Adrenoceptor Antagonists and Antiarrhythmic Agents

Arylpiperazines represent one of the most studied classes of α1 -adrenoceptor (α1 -AR) antagonists. Currently, α1 -AR antagonists are useful in the treatment of benign prostatic hyperplasia, lower urinary tract symptoms or cardiac arrhythmia. The activity of various derivatives of 1-[3-(4-arylpiperazin-1-yl)propyl]pyrrolidin-2-one as α1 -adrenergic receptor antagonists and antiarrhythmic (AA) agents was described using the qualitative inverse Structure Activity Relationship (SAR) model. The three-dimensional structures of the pyrrolidin-2-one derivatives in the basic form were obtained using AM1 semi-empirical quantum chemical calculations. All the molecules were geometry-optimized until the root-mean-square (RMS) gradient value was smaller than 10(-6) a.u. Single-point energy (SPE) calculations were performed at the DFT/B3LYP level of theory using the 6-31G** basis set. The main focus of this inverse SAR study is to find which features cause enhancing of antiarrhythmic properties between subtly different types of activity (α1 -adrenoreceptor antagonists and antiarrhythmic activities). Our SAR study involves the charge distribution in the plane of the pharmacophore model for α1 -AR. Suitable maps of the electrostatic potential were plotted based on the electronic and nuclear charge distribution obtained from the energy calculations. The results of this modelling study indicate that if the terminal arylpiperazine moiety is surrounded by regions of negative electrostatic potential, then the antiarrhythmic activity is blocked.