Re: The sector that paid the highest average margin in 2016 was the NHS
Okay, so your 19p Paracetamol v NHS paracetamol. First off, you have the quality of the tablet, then you have the assurance that the stated dose is correct.
A few years back, a hospital decided to cut costs by purchasing cheaper paracetamol, much as you suggest. They then found they had a high crumble rate to the tablet meaning they couldn't give them to patients meaning they were having to bin over half the tablets as unusable (when a tablet crumbles, the dosage becomes an unknown and that's not permitted in patient care). So the more expensive tablets, which didn't crumble as easily, were cheaper in the end due to lower wastage.
The problem with the dosing was highlighted when some cheaper paracetamol tablets were found to vary in dosage by more than the accepted ammount (I don't have the figures as to what these are, but it was another reason given for why a more expensive tablet was preferred).
So 19p boxes of paracetamol from Asda might be fine for self prescription, but not for an NHS prescription. This is why you're only prescribed paracetamol in dosages greater than over the counter amounts, and why the tablets are higher dosage than you can buy over the counter: They're also a higher quality tablet.
That doesn't mean hospitals aren't ripped off on drug costs, however, it just means that comparing self-prescribed medication to NHS prescribed doesn't work due to different rules over quality.