Any pharmacists/other persons experienced with opiates help me out?

[iloveeverykindofcat]

I have long term pain issues and damage caused by what a friendly physio once called 'the most extreme case of joint hypermobility I've ever seen', blah blah, long story. Just moved up the prescription painkiller ladder from codeine to dihydrocodeine. My GP said this is 'what codeine breaks down into' but I didn't get the chance to ask what he meant by that. Are they the same drug but a higher dose? If so what's the point in changing, why not just prescribe more of the former? Can anyone explain?

Codeine doesn't have any analgesic effect on its own. It only has analgesic effect when it's broken down to morphine by cytochrome P-450 2D6 (CYP2D6). If you were taking any other drugs that inhibit this, you get less pain relief.

Dihydrocodeine is not a prodrug. It does have CYP2D6 activity, but it also has inherently analgesic effect and is 1.5-2× more effective than codeine.

So....was the GP incorrect? If codeine is broken down into morphine, that's something different from Dihydrocodeine, right? Also, if it's not too much trouble - do you have any idea how hard dihydrocodeine is on the liver? (I don't drink at all because my family is prone to liver disease, though I've never personally had any) Thanks for your help. I know I should have asked more questions, but I'm slightly intimidated by the GP I'm presently seeing (interest in this area). He's one of the older men who come over as 'I'm the doctor, do what I say' and I'm a young-looking woman.

Dihydrocodeine metabolises to dihydromorphine which for all intents and purposes is the same as morphine so the GP was correct. It is marginally stronger than codeine.

Both drugs are metabolised in the liver.

Thank you x