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

(S)-enantiomer of tetramisole

Tetramisole carries one chiral stereogenic center and exists as an enantiomeric pair. The anthelmintic activity resides in the (S)-(-)-enantiomer, levamisole. The (R)- isomer harbors undesirable side effects including vomiting. Hence the (S)-enantiomer was marketed as levamisole to replace the racemic tetramisole to treat intestinal worm infestations.

Therapeutic category

Anthelmintic, an antirheumatic drug, an immunomodulator,




Study he heterocyclic ring system and numbering




Edwin Thall, When Drug Molecules Look in the Mirror, Journal of Chemical Education 1996 73 (6), 481DOI: 10.1021/ed073p481; https://pubs.acs.org/doi/10.1021/ed073p481

Drayer, D.E. Pharmacodynamic and pharmacokinetic differences between drug enantiomers in humans: an overview. Clin Pharmacol Ther. 1986 Aug;40(2):125-33. doi: 10.1038/clpt.1986.150.


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