This might be a tough question, but here goes. Does a cyp3a4 inhibitor lower the LD50 or chance of respiratory depression/OD with a single dose of a drug like diazepam? I don't know if these inhibitors affect peak levels much or just lengthen the halflife, which could cause toxicity issues with repeated doses, but probably wouldn't increase the risk of problems with one dosage? The inhibitor in question is a mechanism-based inhibitor, (schisandra berries) not sure if that makes a difference.
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Do cyp3a4 inhibitors increase chance of OD with single dose?
- Thread starter Pine93
- Start date
SirTophamHat
Bluelighter
Yes it will increase the likelihood. With a single drug such as diazepam, unless the dose is already very high, I don't think there is a high risk of fatal RD. Then again it always helps to be aware.
tyrael
Bluelighter
Tbh, a more complex question than you (may) realise....
Firstly, it wouldn't reduce or effect in anyway the LD50. Since LD/TD/ED50s are statistical approximations, calculated under certain generalised conditions. I do get what you're trying to say though...
Simply; inhibition of CYP3A4 will have some effect, but not a great deal overall (even taking into account what's below). It is also too simplistic (actually just incorrect) to say inhibition of an enzyme will increase a drugs efficacy/toxicity, sorry.
Diazepam is bioactive by itself - no metabolism is required, just absorption into areas with GABAr. It is obviously metabolise though - some metabolites themselves are bioactive (nordiazepam [main], oxazepam and temazepam ) some not. (I don't have the info in front of me ATM however) it would mostly depend on which enzymes metabolise into which metabolites and to what degree.
For example, say CYP3A4 metabolised diazepam into an non-active metabolite, this was inhibited, this would mean a greater concentration of the substrate (diazepam) which IS bioactive so yes this would potentiate the effects. However if this enzyme only metabolised 5% of the total dose, then probably no increased effect would be felt.
In the same instance, if CYP3A4 metabolised 40% of diazepam into nordiazepam (its main metabolite), and this was inhibited, you may see an actual *decrease* in effect since not enough transformation is occurring. That 40% of the original diazepam dose would stay as diazepam (which ultimately may not produce an as strong effect).
I hope that makes sense? Your question is actually I'd say at about a 2nd year pharmacology degree level. If you need further explanation lemme know or PM me.
Firstly, it wouldn't reduce or effect in anyway the LD50. Since LD/TD/ED50s are statistical approximations, calculated under certain generalised conditions. I do get what you're trying to say though...
Simply; inhibition of CYP3A4 will have some effect, but not a great deal overall (even taking into account what's below). It is also too simplistic (actually just incorrect) to say inhibition of an enzyme will increase a drugs efficacy/toxicity, sorry.
Diazepam is bioactive by itself - no metabolism is required, just absorption into areas with GABAr. It is obviously metabolise though - some metabolites themselves are bioactive (nordiazepam [main], oxazepam and temazepam ) some not. (I don't have the info in front of me ATM however) it would mostly depend on which enzymes metabolise into which metabolites and to what degree.
For example, say CYP3A4 metabolised diazepam into an non-active metabolite, this was inhibited, this would mean a greater concentration of the substrate (diazepam) which IS bioactive so yes this would potentiate the effects. However if this enzyme only metabolised 5% of the total dose, then probably no increased effect would be felt.
In the same instance, if CYP3A4 metabolised 40% of diazepam into nordiazepam (its main metabolite), and this was inhibited, you may see an actual *decrease* in effect since not enough transformation is occurring. That 40% of the original diazepam dose would stay as diazepam (which ultimately may not produce an as strong effect).
I hope that makes sense? Your question is actually I'd say at about a 2nd year pharmacology degree level. If you need further explanation lemme know or PM me.
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