Chirality

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). …

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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 …

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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 …

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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 …

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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 …

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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 …

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Ethambutol

(S,S)-(+)-Ethambutol is powerful and selective antitubercular drug. It is a classical example of an old drug that was introduced for clinical use in its chirally pure form. Chirality and biological activity Ethambutol contains two constitutionally symmetrical stereogenic centers in its structure and exists in three stereoisomeric forms. An enantiomeric pair (S,S)- and (R,R)-ethambutol, along with the achiral stereoisomer called meso-form. The activity of the drug resides in the (S,S)-(+)-enantiomer which is 500 and 12 fold more …

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Levofloxacin

Levofloxacin is a third generation fluoroquinolone that is widely used in the treatment of mild-to-moderate respiratory and urinary tract infections due to sensitive organisms.  Levofloxacin is an antibacterial prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of certain bacterial infections, such as community-acquired pneumonia, acute worsening of chronic bronchitis, anthrax, urinary tract infections, acute sinus infections, and others. Chirality and biological activity Levofloxacin, the S-enantiomer of the previously marketed …

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Ascorbic acid

L-(+)-Ascorbic Acid is another old chiral drug from natural source. It is a water-soluble vitamin (Vitamin C). Ascorbic acid is a potent reducing and antioxidant agent that functions in fighting bacterial infections, in detoxifying reactions, and in the formation of collagen in fibrous tissue, teeth, bones, connective tissue, skin, and capillaries. Found in citrus and other fruits, and in vegetables, Vitamin C cannot be produced or stored by humans and must be obtained in the …

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Quinine

Most fascinating old chiral drug, from historical point of view, is Quinine. It is known that by early 1600s quinine was being used by South American natives, in Peru, Ecuador, as a crude preparation from the bark of the Cinchona tree for the treatment of malaria. Chirality and biological activity Quinine contains two major fused ring systems: aromatic quinoline and bicyclic quiniclidine. The molecule contains four stereogenic carbon centers at C-3, C-4, C-8 and C-9, respectively …

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