Answer to Question #178770 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.

Answer 1

1.

Adverse Reactions of isomeric drugs Isomerism can lead to different therapeutic uses and adverse drug reactions like  Quinine has antimalarial activity while quinidine has an antiarrythmic property.  L-sotalol is alpha-blocker while d-sotalol is antiarrythmic.

2.

Thalidomide is Recemic -

One enantiomer is effective against morning sickness while other enantiomer is teratogenic.

Enantiomer are inter convertible in Vivo

Dosing of single enantiomer lead to D and L isomers eventually being present in patients serum and would not prevent adverse effects

Ibuprofen

S- form is active and R is inactive .

Used for headache,dental pain, menstrual cramps arthritis, reduce used as NSAID prevent inflammation.

Ibuprofen

Ibuprofen is available as S+R Recemic mixture because S is active and R is inactive.

It's 50-50 mixture makes R medicinal like S . Hence it is available as 50-50 recimic mixture

Resolution of recimic mixture is done by three method

1. Mechanical is separate crystals based on difference in their shapes

2. Convert enantiomer in Recemic mixture diasteomer.and then resolve by normal technique.

3. By using enzyme as enzymes are stereo specific choral protein hence thy react with only one enantiomers while other remain unchanged.

3.

Thalidomide is Recemic -

One enantiomer is effective against morning sickness while other enantiomer is teratogenic.

Enantiomer are inter convertible in Vivo

Dosing of single enantiomer lead to D and L isomers eventually being present in patients serum and would not prevent adverse effects

Ibuprofen

S- form is active and R is inactive .

Used for headache,dental pain, menstrual cramps arthritis, reduce used as NSAID prevent inflammation.

Ibuprofen

Ibuprofen is available as S+R Recemic mixture because S is active and R is inactive.

It's 50-50 mixture makes R medicinal like S . Hence iit is available as 50-50 recimic mixture

4.

The separation of a racemate into its components, the pure enantiomers, is called a chiral resolution. There are various methods, including crystallization, chromatography, and the use of enzymes