Valliappan Kannappan

Dilevalol

Dilevalol is the (R,R)-diastereoisomer of labetalol. Labetalol has been in clinical use since 1977 for the treatment of hypertension.  Labetalol is an adrenergic antagonist used to treat high blood pressure. It has a role as an antihypertensive agent, a sympatholytic agent, an alpha-adrenergic antagonist and a beta-adrenergic antagonist. Chirality and drug withdrawals Labetalol has two stereogenic centers and consequently exists as four stereoisomers. It is a diastereoisomeric mixture of approximately equal amounts of all four possible stereoisomers …

Dilevalol Read More »

Thalidomide

Thalidomide was a racemic therapeutic and prescribed to pregnant women to control nausea and vomiting. The drug was withdrawn from world market when it became evident that the use in pregnancy causes phocomelia (clinical conditions where babies are born with deformed hand and limbs). Later in late 1970s, the thalidomide enantiomers were separated and enantioselective studies indicated that the (R)- enantiomer, the good partner, is an effective sedative, the (S)-enantiomer, the evil partner, harbors teratogenic …

Thalidomide Read More »

Indacrinone

Indacrinone is an orally active, indanone-based loop diuretic patented by American pharmaceutical company Merck and Co as mixture of two enantiomers. In healthy volunteers, the racemic mixture of indacrinone exhibited greater natriuretic potency than furosemide, with a slower onset and longer duration of action. Furthermore, single doses of indacrinone decreased serum uric acid concentrations and increased uric acid clearance, while similar doses of furosemide generally had the opposite effects. Differences in the pharmacologic effects of …

Indacrinone Read More »

Levocetirizine

Levocetirizine, is chiral switch cetirizine, employed for allergies. It is a third generation, non-sedating, selective histamine H1 receptor antagonist, with antihistamine, anti-inflammatory and potential anti-angiogenic activities. Levocetirizine is used to relieve the symptoms of hay fever and hives of the skin. It is an antihistamine that works by preventing the effects of a substance called histamine, which is produced by the body.  Chirality and Biological activity Cetirizine carries one stereogenic carbon (indicted by an red arrow mark) and …

Levocetirizine Read More »

Escitalopram

Citalopram belongs to a class of antidepressant agents known as selective serotonin-reuptake inhibitors (SSRIs). It is indicated for the treatment of depression. Chirality and biological activity Citalopram has one stereocenter, to which a 4-fluoro phenyl group and an N, N-dimethyl-3-aminopropyl group are linked. As a consequence the molecule exists as an enantiomeric pair, the S-(+)-citalopram and R-(–)-citalopram. The selective serotonin-reuptake inhibitor  activity resides primarily in the  S-enantiomer (eutomer) while the R-enantiomer is 30-fold less potent (distomer). …

Escitalopram Read More »

Levobupivacaine

Bupivacaine is a long acting local anesthetic in use for many years as a spinal/epidural anesthetic for childbirth and orthopedic procedures, such as hip replacement. It is marketed by AstraZeneca under the trade name Chirocaine. It acts by blocking Na+ channels and also has actions on the heart, which restrict its use by intravenous injection for regional anesthesia. Chirality and Biological activity Bupivacaine is a racemic drug. This an example where the distomer shows toxic effect …

Levobupivacaine Read More »

Propoxyphene

Chiral twins with independent therapeutic value Propoxyphene is a classical example of a synthetic chiral drug where the enantiomers of a chiral drug exhibit desirable but different therapeutic activity. Example of such biological behavior is exemplified by some of the natural products as well (e.g., quinine and quinidine) with anti-malarial and anti-arrhythmic activity. Chirality and biological activity Propoxyphene carries two stereogenic centers meaning it can exist in two pair of enantiomers (4 stereoisomers). One of …

Propoxyphene Read More »

Dexibuprofen

The chiral switches of ‘profen’ NSAIDs Chiral switches have been successful in two non-steroidal anti-inflammatory drugs (NSAIDs) – ibuprofen and ketoprofen. The switch of ibuprofen is based on chiral inversion; (±)- and (S)-ibuprofen can be viewed as being essentially bioequivalent’. Ibuprofen carries a stereogenic center in the propanoic acid side chain and exists as a pair of enantiomers. Dexibuprofen is (S)-(+)-Ibuprofen. Chiral Inversion COX inhibition resides exclusively in the (S)-enantiomer, as shown by in vitro studies …

Dexibuprofen Read More »

Salbutamol

Salbutamol (also known as Albuterol ) is used to prevent and treat wheezing and shortness of breath caused by breathing problems (such as asthma, chronic obstructive pulmonary disease). Salbutamol is a short-acting, selective beta2-adrenergic receptor agonist used in the treatment of asthma and Chronic obstructive pulmonary disease (COPD). Synonym Albuterol Chirality and biological activity Salbutamol is formulated as a racemic mixture of the R- and S-isomers. Bronchodilator activity resides in R-(-)-Salbutamol (eutomer); S-Salbutamol (distomer) is inactive. The …

Salbutamol Read More »

Esomeprazole

Esomeprazole is used to treat conditions where there is too much acid in the stomach. It is used to treat duodenal and gastric ulcers, erosive esophagitis, gastroesophageal reflux disease (GERD), and Zollinger-Ellison syndrome, a condition wherein the stomach produces too much acid. It was launched by AstraZeneca, in 2000. Esomeprazole magnesium [AstraZeneca; http://www.astrazeneca.com] (gastrointestinal). Chirality and biological activity Esomeprazole is the (S)-(−)-enantiomer of (±)-omeprazole. It is a chiral switch (Read more about chiral switch @ my page …

Esomeprazole Read More »