Is Ibuprofen sold as a single enantiomer or racemic mixture?

Sold as racemate (both forms); some countries sell pure S-ibuprofen (dexibuprofen)

Ibuprofen Enantiomers - Chirality in Pharmacology

What happens with Ibuprofen enantiomers?

Ibuprofen is a NSAID (Anti-inflammatory). The S-enantiomer is Active COX inhibitor, while the R-enantiomer is Inactive but converts to S-form in vivo. R-ibuprofen is pharmacologically inactive but the body slowly converts it to the active S-form. This is why racemic ibuprofen still works.

Drug Name	Ibuprofen
Drug Class	NSAID (Anti-inflammatory)
R-Enantiomer Activity	Inactive but converts to S-form in vivo
S-Enantiomer Activity	Active COX inhibitor
FDA Status	Sold as racemate (both forms); some countries sell pure S-ibuprofen (dexibuprofen)
Year of Discovery	1961
Clinical Significance	R-ibuprofen is pharmacologically inactive but the body slowly converts it to the active S-form. This is why racemic ibuprofen still works.

Introduction

Ibuprofen is one of the most widely used pain relievers in the world. You might know it as Advil or Motrin. But did you know that only one mirror form is actually active?

Structure Comparison

Both enantiomers share the formula C₁₃H₁₈O₂. The structure features a para-isobutylphenyl group attached to a propionic acid through the chiral carbon.

Chiral Center

The chiral center is the alpha-carbon of the propionic acid chain. It carries four different groups: the aryl ring, a methyl group, a carboxylic acid, and a hydrogen.

Pharmacological Differences

S-ibuprofen inhibits both COX-1 and COX-2 enzymes, blocking prostaglandin synthesis and reducing pain and inflammation. R-ibuprofen does not fit the COX active site.

Clinical Impact

Unlike thalidomide, R-ibuprofen is not harmful - it is simply inactive. The body has an enzyme (alpha-methylacyl-CoA racemase) that slowly converts R to S, so racemic ibuprofen still works.

Key Takeaway

Ibuprofen is sold as a racemate because the R-form is harmlessly converted to the active S-form in the body. Pure S-ibuprofen (dexibuprofen) offers faster onset but is not widely available.

Visualize R and S enantiomers side by side with activity indicators and pharmacological profiles.

Compare Ibuprofen Enantiomers in 3D