SQL & PL/SQL

Here is the trigger:

CREATE OR REPLACE TRIGGER DRUGREPLACEMENT
AFTER INSERT ON PHARMACEUTICALS
REFERENCING NEW AS newDrugs
FOR EACH ROW
WHEN (newDrugs.drugname = newDrugs.genericname)
BEGIN
UPDATE prescription
SET pharmaceuticalid = newDrugs.drugID
WHERE pharmaceuticalid IN(SELECT pharmaceuticalid FROM prescription, pharmaceuticals WHERE drugid = pharmaceuticalid AND newDrugs.genericname = pharmaceutical.genericname);
END;

Error is:
Error(2,1): PL/SQL: SQL Statement ignored
Error(3,24): PL/SQL: ORA-00904: "NEWDRUGS"."DRUGID": invalid identifier

pharmaceuticalid is a number in my prescription table.
drugid is a number; genericname and drugname are both varchars in my pharmaceuticals table. Any idea why I am getting these errors? (I tried putting quotes around newdrugs.drugid but then it just said "newdrugs.drugid" is invalid. Thanks for your help
-Brian