I now know the official difference between an opiate and opioid. Opiates occur naturally (the medicinally useful ones are codeine and morphine), and opioids are synthesised from a starting opiate. So dihydrocodeine, Tramadol and pethidine are opioids.
I am stupidly amused. if you open the structure of codeine and dihydrocodeine as two tabs in the same window, you can rapidly click between them to make your own animated gif. Who'd've thought it - dihydrocodeine is just codeine with its double bond saturated. Huh. btw, those links are from a site calling itself Just For Chemists, which leads to deceptively simple structures for things like pethidine unless you know that Me is a methyl group (-CH3), Et is an ethyl group (-CH2CH3) and Ph is a benzene ring. When I post my List of Interesting Drugs I've Taken Recently, I'll modify the structures to be complete.
omg, I've just found a link to The Synthesis of Tramadol. That rocks. Sadly, it seems to be the only one on there. I'm just... amazed... that the highly toxic-to-me salicylic acid can be reduced & Grignarded and turned into something that doesn't kill me.
And I'm even more stupidly amused to discover that I have now Officially taken a Class A Drug. Does it still count as a Class A Drug if I took it for medicinal purposes under prescription? I want to know! Are these pain attacks going to sully my "Never taken an illegal drug in my life except alcohol a few times when underage" reputation?!
Hold on a minute... according to the list of drugs on Wikipedia, codeine is a Class B drug. How the hell is something that is legally available at any UK pharmacy without prescription Class B? That list has to be screwy.
Further update: the official UK Home Office website tells me that codeine/dihydrocodeine don't count as Class B if they're in a preparation which contain less than 100mg of codeine and/or less than 2.5% codeine. Likewise, morphine injections are only Class A if the preparation contains more than 0.2% of morphine base. See for details. Annoyingly, it doesn't translate the official Government categories into media-speak - so while I know that Schedule 1 = Class A and Schedule 2 = Class B, I've no idea what Schedules 3, 4 Part 1 and 4 Part 2 are. Schedule 5 is unrestricted for sale by licensed pharmacists.
So apparently I'm up to 2 Class As (morphine and pethidine), 2 Class Bs (codeine and dihydrocodeine), and one Schedule 4 Part 1 (whatever the hell that means - Zolpidem). But the Government doesn't care because I took them legally. So all I want to know is whether I've lost purity test points (where "technicalities count")? Anyone more pedantic than me welcome to explain.