In the pharmacology results you'll see properties from the drugbank dataset where these are available


 "inDataset": "http://linkedlifedata.com/resource/drugbank",
 "drugType": [
 "approved",
 "smallMolecule",
 "investigational"


This will get your results back. In your application you could then filter on "approved" or any other value from drugbank (see their site for the different labels). and you should be able to filter.