Fighters Only Magazine has an interesting tidbit:

Speaking to Fighters Only earlier, Dr. Chris Lam (pictured) explained that the three drugs - Hydrocodone, Oxymorphone, and Hydromorphone - are all opiates, which are “probably the most powerful pain killer which are routinely used in medicine, normally being reserved for severe pain such as cancer pain”.

“In the UK at least, it would be very unusual for a doctor to prescribe opiates of the sort found in his test for muscular injuries such as hamstring injuries,” he said, referring to Parisyan’s claim that he took the drugs because of hamstring pain.

“It is also unusual to be given a cocktail of opiates as was found in his urine sample.”

...

“One of the main concerns with prescribing opiates is that they potentially can be addictive and habit forming especially if prescribed inappropriately,” he said.

Dr Lam is a British physician who is used by both the British Board of Boxing Control and the UFC as a ringside doctor for events in the UK and Ireland, where he has tended to the likes of Mirko ‘CroCop’ Filopovic, Mark Coleman and Matt Hughes.

There are three issues to unpack here. First, while not out of the question that one person could be prescribed all three of those painkillers simultaneously (or be allowed to take all three simultaneously), how likely is it that Karo actually has all three prescribed to him by medical professionals who understand precisely what Karo was ingesting? One can only hope there's no doctor shopping going on here.

Second, are the injuries Karo has so severe that he needs one - much less three - prescribed painkillers to cope with the pain?

Third, even if Karo has been prescribed these drugs by licensed medical doctors who are aware of everything he was ingesting, what athletic commission would approve such a fighter to be competing in high-level professional MMA bouts given those conditions? Karo may claim he has prescriptions for all three drugs and perhaps he does, but that in no way absolves him of the fact that taking those drugs only masks serious underlying health issues the commission would be forced to look into.

I'm sure there is a diversity of opinion on this matter, but the more I learn about the situation and the more Karo tries to explain himself, the more concerned I become.