A patient could discontinue taking medication or simply discontinue the medication. Only a trial, or a subject's participation in it, can be terminated. Admission or entry already imply moving towards and so the into is superfluous. In some instances, it may be better to use the active voice and state that 'the subject entered the study'. If you must use a double negative, make sure you get it right.
Expiration is the phase of the respiratory cycle during which air is expelled from the lungs.
After a career in academic medicine, he worked at the Institute of Aviation Medicine in Farnborough, and has spent the last 12 years in the pharmaceutical industry, as head of various Phase I Units in CROs and mainstream Pharma companies. In these circumstances it should be the investigator, rather than the drug, that became unblinded. Perhaps this would be better phrased as 'premature breaking of the blinding code'. Constructions such as 'data was verified' are incorrect, use 'data were verified'. One cannot diagnose a patient, only a disease.