Stereochemistry and Its Applications in the Pharmaceutical Industry

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CHEM 305

Stereochemistry and its applications in the pharmaceutical industry

The link between stereochemistry and pharmaceuticals are the connections of the chiral and with stereochemistry being a unique science concerned with the study of how molecules are affected by the way their atoms are arranged in space. It is also known as three-Dimensional chemistry. Stereochemistry has become a significant issue for both pharmaceutical industry and the regulatory authorities. There are different types of stereoisomers especially enantiomers. Accordingly, this workshop reviews the concepts of stereochemistry and enantiomers, emphasizes the potential biological and pharmacological differences between the 2 enantiomers of a drug, and highlights the clinical experience with single enantiomers of the selective.

Most natural products, the essential products of life, are asymmetric and this established the only well marked line of demarcation between chemistry of dead matter and the chemistry of living matter. So, the importance of stereochemistry in drug action is gaining greater attention in medical practice, and a basic knowledge of the subject will be necessary for clinicians to make informed decisions regarding the use of single-enantiomer drugs. For some therapeutics, single-enantiomer formulations can provide greater selectivity for their biological targets, improved therapeutic indices, and/ or better pharmacokinetics than a mixture of enantiomers. More stereochemically pure drug agents will become clinically available and pharmacists will be relied upon for their knowledge and expertise. (Elmeligie, 2016)

With there being more single-enantiomer drugs available promises to provide clinicians with secure, better-tolerated, and more efficacious medications for curing patients. It is incumbent upon the practicing physician to have the proper knowledge with the basic properties of chiral pharmaceuticals discussed. Each enantiomer of a given chiral drug may have its own pharmacologic profile, and a single-enantiomer formulation of a drug may possess different properties than the racemic formulation of the same drug. Examples of naturally occurring atropisomers are Vancomycin and Knipholone, which is found in the roots of Kniphofia Foliosa of the family Asphodelaceae. (Owens & McConathy, 2003)

When both a single-enantiomer and a racemic formulation of a drug are available, the information from clinical trials and clinical experience should be used to decide which formulation is most appropriate. (Owens & McConathy, 2003)

Atropisomers are stereoisomers resulting from hindered rotation about single bonds where the steric strain barrier to rotation is high enough to allow for the isolation of the conformers 4, 5. The word atropisomer is derived from the Greek a, meaning not, and tropos, meaning turn.

Considerations in the area of antimicrobial agents. In the current regulatory climate all the components present in a medicinal product require justification and as has been observed in other therapeutic areas, the introduction of single stereoisomers of both new and existing chiral drugs is likely to increase called racemic switches.

However, such introductions are not without problems and may provide unexpected results. Labetalol, an established combined drug blocking certain genes that are not used in the treatment of cardiovascular disease. It contains two chiral centers and the marketed material is a mixture of all four stereoisomeric forms. Of these stereoisomers, the blocking activity resides in the R, R-isomer, the a-blocking activity in the S, S-isomer and the remaining pair are essentially inactive. Clinical trials with the single blocking, R, R-isomer, named dilevalol, resulted in elevated liver function tests in a small number of patients. (He, Nguyen, & Pham-Huy, 2006) R being the Latin term rectus means to the right or clockwise, and S is Latin for sinister, the left or counterclockwise. There are precise rules based on atomic number and mass for determining whether a certain chiral center has an R or S configuration.

This toxicity had not been observed with labetalol and resulted in the withdrawal of the single isomer. Why such toxicity is not observed with the isomeric mixture is not clear, but this example does illustrate that removal of the