Dihydrocodeine

[Jen the 3rd]

Is dihydrocodeine stronger than codeine because of bioavailability (increased solubility) or because of the therapeutic index? Any pharmacokinetics whizzes out there?

[SolomonQ]

I would have thought it was because of DHC's higher affinity for the opiod receptor, DHC actually has lower bioavailabilty than codeine (20% VS 90%).

[Shwampa]

(docs were not sure but thought that was most likely.)

What do you mean? Just a guess about a fracture from your doctor!

Just surprised they went straight to DHC rather than codeine first. If it's very sore 400mg of ibuprofen won't help that much, your doctor could have prescribed diclofenac 75mg bd as long you don't have problems using it.

If you have to use the full dose of DHC everyday for some time, avoid to stop abruptly.

Do you get asthma attacks? (DHC release histamine) if yes avoid.

[Shwampa]

Is dihydrocodeine stronger than codeine because of bioavailability (increased solubility) or because of the therapeutic index? Any pharmacokinetics whizzes out there?

If you can find a copy of this article you might have the answer:

J Pharm Pharmacol. 1973 Dec;25:Suppl:104P-108.

The influence of reducing the C7-C8 double bond of codeine to give dihydrocodeine on the relative physiological availability of the drugs in man.

Vaughan DP, Beckett AH.

[H4U2C]

Is dihydrocodeine stronger than codeine because of bioavailability (increased solubility) or because of the therapeutic index? Any pharmacokinetics whizzes out there?

Dihydrocodeine is approximately twice as strong as regular codeine, and its not because of bioavailability- its because of the double hyrogen atom in its chemical structure.

[SolomonQ]

Dihydrocodeine is approximately twice as strong as regular codeine, and its not because of bioavailability- its because of the double hyrogen atom in its chemical structure.

Its actually 1 to 1.5 stronger, and whats a "double hydrogen atom"? no such thing, two hydrogen atoms would be hydrogen gas, did the "Dihydro-" part throw him/her off, any chemistry amateur would know that means it is the basic codeine chemical structure with two extra hydrogens, but reading the post again and considering this is a pharmacy forum, full of people who have studied chemistry to some level, it's actually quite funny.

[H4U2C]

Its actually 1 to 1.5 stronger, and whats a "double hydrogen atom"? no such thing, two hydrogen atoms would be hydrogen gas, did the "Dihydro-" part throw him/her off, any chemistry amateur would know that means it is the basic codeine chemical structure with two extra hydrogens, but reading the post again and considering this is a pharmacy forum, full of people who have studied chemistry to some level, it's actually quite funny.

Well ok how about this- dihydrocodeine gets converted to "dihydromorhine" in the brain whereas codeine is just converted into 10% "morphine" in the brain and also 10% of cacasians have poor cyp450 liver enzyme which actually procesess the drug and codeine is affected by this whereas dihydrocodeine isent

[SolomonQ]

Well ok how about this- dihydrocodeine gets converted to "dihydromorhine" in the brain whereas codeine is just converted into 10% "morphine" in the brain and also 10% of cacasians have poor cyp450 liver enzyme which actually procesess the drug and codeine is affected by this whereas dihydrocodeine isent

wow!!!, and all because of the double hydrogen, chemistry's amazing isnt it!!!

You are very amusing, you'd make a very good comedian, ever thought of changing the day job? oh, Look what you've gone and done, contradict yourself, first you say Dihydrocodeine(DHC)-->(Dihydromorphine)DHM conversion is in the brain then a line later its in the liver("hepatic")??

I did my fourth year essay on non-hepatic metabolism of drugs and I cant remember the brain having such an extensive role as you describe.

O-demethylation of DHC by the CYP 2D6 group of enzymes, happens mainly in the liver to create DHM but In reality this is less than 10%. Other enzymes create different metabolites which circulates in the blood, reaching the brain and CNS.

Pharmacological effect of DHC seems to be independent of CYP 2D6 polymorphisms, so therefore the DHM cannot be responsible for it's activity, also DHM is not very lipophillic so can't cross the brain-blood barier.

finally, it is also disputed as to whether morphine is entirely responsible for the effects of codeine, as other metabolites seems to show similar properties.

[Shwampa]

Let's tidy up that and invite you to: http://psy.psychiatryonline.org/cgi/...t/44/6/515.pdf

[H4U2C]

wow!!!, and all because of the double hydrogen, chemistry's amazing isnt it!!!

You are very amusing, you'd make a very good comedian, ever thought of changing the day job? oh, Look what you've gone and done, contradict yourself, first you say Dihydrocodeine(DHC)-->(Dihydromorphine)DHM conversion is in the brain then a line later its in the liver("hepatic")??

I did my fourth year essay on non-hepatic metabolism of drugs and I cant remember the brain having such an extensive role as you describe.

O-demethylation of DHC by the CYP 2D6 group of enzymes, happens mainly in the liver to create DHM but In reality this is less than 10%. Other enzymes create different metabolites which circulates in the blood, reaching the brain and CNS.

Pharmacological effect of DHC seems to be independent of CYP 2D6 polymorphisms, so therefore the DHM cannot be responsible for it's activity, also DHM is not very lipophillic so can't cross the brain-blood barier.

finally, it is also disputed as to whether morphine is entirely responsible for the effects of codeine, as other metabolites seems to show similar properties.

My goodness!! You are the king king Solomon- i havent given up yet!