Image Number 4 for United States Patent #6225321.
The nalbuphine polyester derivative is related to a novel long acting agent. The nalbuphine polyester derivative is R--[CO-NAL].sub.n wherein n is an integer from 2-4 and, in which the R is selected from a saturated or nonsaturated, substituted or unsubstituted, aliphatic or aromatic group having 1 to 40 carbon atoms. The process for producing the derivative includes esterifying nalbuphine with a saturated or unsaturated fatty acid or a halogen compound of the fatty acid with an acid anhydride. A pharmaceutical composition contains the derivative and a pharmaceutically acceptable carrier, which can be administered to an animal or person for treating pain.