Thanks for the tip MLA. Although I did know about that one. Works for some opioids, but not others. Not had any grapefruit juice in a while actually, might just pick some up, I love the stuff, especially the kind with the fruit pulp still in it. Or better yet, fresh grapefruit for breakfast, reminds me of when I was little, used to have it for breakfast when I went to visit my (now dead) grandmother.
I'm thinking of asking my doc about flupirtine, although I'm not sure if its used in the UK or not. Its a novel, non-NSAID, non-steroidal, non-opioid analgesic. Not to replace my oxy, indomethacin (strong arsed NSAID) and corticosteroid shots but as an add-on.Novel mode of action, IIRC it works by works by opening of a subtype of inward-rectifying G-protein coupled potassium channels, having downstream effects as an NMDA receptor antagonist, stabilizing the voltage-dependent Mg2++ blockade of the NMDAr complex ion channel. That should give it some efficacy
against neuropathic pain, something which opioids are not very good at.
I'd quite like to give it a trial if its available, nonaddictive, with apparently few side effects and little development of tolerance.
The GFJ trick works by inhibition of hepatic cytochrome P450-3A4 enzymem one of a fair few CYP-P450 type liver enzymes, and one that generally munches up many opioids into inactive metabolites, and it does the same for benzodiazepines also, and will make them last longer.
In fact, quite a lot of meds warn to be careful with, or not to consume grapefruit juice whilst taking XYZ medication.