US Patent 7557128 Optically active isomers of ketotifen and therapeutically active metabolites thereof

Racemic norketotifen, racemic 10-hydroxy-ketotifen, racemic 10-hydroxy-nor-ketotifen and optically active isomers of ketotifen, norketotifen, 10-hydroxy-ketotifen and 10-hydroxy-norketotifen were found to have antiallergic and anti-inflammatory effects while being devoid of the severe dose-limiting sedative side effects of Ketotifen.