The nurse gave the woman undiluted promethazine, which Ms Baker judged a breach of the code of patients' rights and led to her recommendation the nurse undertake training on IV drugs.
The woman became drowsy, a recognised side effect of promethazine, soon after the infusion began and could not be roused. She was taken to a hospital by ambulance and was discharged the next day. She was later diagnosed with vein inflammation and suffered weakness in her left arm, which became swollen and painful if she knocked it.
The patient told the commissioner's office of the infusion, "... I was crying, with my face screwed up saying it's burning and stop! I'm not sure what else she [the nurse] expected from someone to alert her it was intolerable ..."
The nurse said that although the woman had stated that the infusion was tender, she did not ask her to stop.
Ms Baker said she was not sufficiently persuaded the woman sought a halt.
The deputy commissioner's medical adviser, Dr David Maplesden, said the doctor's diagnosis was unclear, but the woman did not appear to be in anaphylaxis. It was likely she was suffering a mild to moderate allergic reaction, for which the oral antihistamine was the proper treatment.
Dr Maplesden was not convinced IV promethazine was the right course. If the doctor had truly felt her life was potentially at risk, as he had stated, the woman should have been given intramuscular adrenaline.
He said there was some confusion in the use of adrenaline and antihistamines and although the doctor's care of the woman was inconsistent with best practice, "it was consistent with common practice".
Medsafe had added to the confusion: its apparent acceptance that IV promethazine could be used in emergencies such as treatment of anaphylaxis seemed inconsistent with current evidence and contradicted Australian guidelines.
Medsafe told the Herald it would review Dr Maplesden's comments about the promethazine datasheet and the Australian guidelines.