Strategy The basic aspect is to provide the right chiral environment where by the enantiomeric pair become distinguishable. In HPLC how do we construct the chiral environment? To understand this let us look at the variables available, in the HPLC system, that can be exploited for this purpose. The following is a schematic diagram of …
What is chiral chromatography? Chiral chromatography is now widely understood and applied in daily life. The correct phrase, however, is “enantioselective chromatography”. Chiral chromatography has developed into the most popular method for enantiomeric purity assessment and pure enantiomer separation, both on an analytical and preparative scale. The initial step in any investigation into enantioselective synthesis …
Stereochemistry, in particular chirality, is known to us as early as 1809, when Malus, Arago and Biot discovered plane polarized light and its characteristics. It is observed that during 1950s to the 1970s, the “Golden Age” of drug discovery & development, stereochemistry was largely ignored resulting in approximately 57% of pharmaceuticals being marketed as racemates …
Levamisole is used as anthelmintic agent to get rid of the intestinal worms. It is (S)-(-)-enantiomer of tetramisole. This drug is used in veterinary to treat hookworm infections. Levamisole also finds therapeutic application in the treatment of colon cancer when given in conjunction with fluorouracil. Chirality and biological activity Tetramisole carries one chiral stereogenic …
Beta blockers, also spelled β-blockers, used as antihypertensive agents (lowering blood pressure), represent a class of chiral drugs that are marketed as racemates since the distomer exhibits no undesirable adverse effects. Three most important β-blockers viz. propranolol, atenolol, and metoprolol are marketed as racemic mixture. Chirality and biological activity β-blockers are aryloxy propanolamines with one stereogenic …
Levodopa, L-Dopa, belong to a class of medications called dopamine agonists. L-Dopa is used to increase dopamine concentrations in the treatment of Parkinson’s disease. Most commonly, clinicians use levodopa as a dopamine replacement agent for the treatment of Parkinson disease. L-dopa is the precursor to dopamine and crosses the blood-brain barrier to increase dopamine neurotransmission. Chirality and Biological activity L-dopa, …
(±)-Terodiline, the antianginal agent, perhaps represents the best authenticated example of a drug that had to be withdrawn from the world market as consequence of proven stereospecific toxicity. Terodiline has a close similarity to prenylamine from a structural and pharmacological view point. It was firs marketed as an antianginal agent but it exhibited urinary retention …
(±)-Prenylamine, an antianginal agent, was introduced in the market since early 1960. Reports associating Prenylamine with prolongation of the QT interval, ventricular tachycardia, and ventricular fibrillation started to appear. Some of these events had a fatal outcome and the drug was withdrawn from the market world-wide in 1988. Chirality and drug withdrawals Prenylamine is chemically …
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 …
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 …