Isomerism finds its importance in the field of clinical pharmacology and pharmacotherapeutics, as isomers differ in their pharmacokinetic and pharmacodyanmic properties. Drug isomerism has opened a new era of drug development. Currently, knowledge of isomerism has helped us in introducing safer and more effective drug alternatives of the newer as well as existing drugs. Many existing drugs have gone chiral switch i.e., switching from racemic mixture to one of its isomers. Cetrizine to levocetrizine is one of such examples, where effective and safer drug has been made available. In this article, we have attempted to review the basic concepts of stereochemistry and chirality and their significance in pharmacotherapeutics. Various pharmacological aspects such as pharmacokinetic and pharmacodynamic variations resulting out of chirality has been discussed in detail in this article.

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Background Ventricular tachycardia (VT) and premature ventricular complexes (PVC) most frequently occur in the context of structural heart disease. However, the burden of idiopathic ventricular arrhythmias (VA) in the general population is unknown. Methods and Results We identified incident cases of idiopathic VA between 2005and 2013 from Olmsted County, MN using the Rochester Epidemiology Project database. For PVC cohorts, we included those with frequent (defined as ≥100 PVC/24 hours) symptomatic PVCs. We defined idiopathic VA-associated cardiomyopathy as an EF drop of ≥10% from baseline. Between 2005 and 2013, we identified 614 individuals with incident idiopathic VA. (229 [37.3%] were male, average age was 52.1 ± 17.2 years). Of these, 177 (28.8%) had idiopathic VT, 408 (66.5%) had symptomatic PVCs and 29 (4.7%) had idiopathic VA-associated cardiomyopathy. The age- and sex- adjusted incidence rates in 2005–2007, 2008–2010 and 2011–2013 were 44.9 per 100,000 (95% CI 38.0–51.8), 47.6 per 100,000 (95% CI 40.8–54.5) and 62.0 per 100,000 (95% CI 54.4–69.6), respectively. In idiopathic VT, there was an increase in incidence rate with age s (P<0.001) but not between sexes (P=0.12). The age-adjusted incidence of symptomatic PVC was higher in females than males (46.2 per 100,000 [95% CI 40.9–51.6] versus 20.5 per 100,000 [95% CI 16.8–24.3], p<0.001). The small number of individuals with idiopathic VA-associated cardiomyopathy precluded any formal testing. Conclusions The incidence of idiopathic VA is increasing. Furthermore, overall incidence increases with age. While the rate of idiopathic VT is similar across genders, women have a higher incidence of symptomatic PVC.

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