Answer to Question #179237 in Organic Chemistry for Sam

Question

Analyse the therapeutic or chemical effects of isomerism. Research the drugs thalidomide and ibuprofen, and their therapeutic effects. Both drugs have optical isomers: compare the structures and properties of the optical isomers in each case study. Explain why one of these drugs is only available as a single optical isomer whilst the other is sold as a racemic mixture (a 50:50 mixture of both optical isomers). Discuss the implications of having to separate a racemic mixture into its stereoisomers and the implications if the two stereoisomers are not separated, with reference to the two drugs.

(This provides evidence for D3)

Answer 1

Stereoisomers differ in pharmacokinetic and pharmacodynamic properties. Pharmacokinetic differences resulting out of stereoisomerism can be in absorption like L-Methotrexate is better absorbed than D-Methotrexate, Esomeprazole is more bioavailable than racemic omeprazole; in distribution like S-Warfarin is more extensively bound to albumin than R-Warfarin, hence it has lower volume of distribution.[5,9] Levocetrizine has smaller volume of distribution than its dextroisomer,[10] d-Propranolol is more extensively bound to proteins than l-Propranolol; in metabolism like S-Warfarin is more potent and metabolized by ring oxidation while R-Warfarin is less potent and metabolized by side chain reduction, half life of S-Warfarin is 32 hours while it is 54 hours for R-Warfarin