Aug 17 (Reuters) - Australian biomedical giant CSL Ltd on Wednesday reported a 6% drop in annual profit as collections of plasma, the key ingredient of its treatments, were subdued in the first half and hit sales of core plasma therapies.

CSL posted an underlying net profit after tax of $2.24 billion on a constant currency basis for the year ended June 30. (Reporting by Roushni Nair in Bengluru; Editing by Shailesh Kuber)