If we know that a drug's effective half life is 18 hours, and that the drug potentiates alcohol, then two questions would emerge: 1) why this drugs usual dosage is every 8 hours, as a therapuetic index (yet alone the recreational values), and 2) why this the drug could be demonstrated to have a mild interaction with alcohol, (enough to prove that it is still acting, though not clinically significant.) The particular drug in question is metabloized in the liver, but not with the same chemical markers as ethanol, and is also excreted via renal function. (i.e. the kidneys), and the liver/ kidney function have been demonstrated to be normal by routine blood draw. Is there something I'm not considering here?
Misc Question on Drug Half-life (Chemistry Question)
- Thread starter torboy
- Start date
Kittycat5
Bluelighter
- Joined
- Dec 23, 2013
- Messages
- 9,361
Duration of therapeutic action is not always the same as half life and thus may require dosing intervals shorter than the half life. Methadone is a good example. Half life of 8-60 hours but analgesic effect often only 4 to 6 hours so dosed 3-4 times daily for pain.
Talking about Cyclobenzaprine HCL., Diphenhydramine HCL, and Hydroxyzine HCL. Cyclobenzprine has a half-life which can be greater than 24 hours, but yet is dosed MUCH more frequently, within theraputic index. Trying to figure out how one would perhaps change the dose of these drugs if changing the route to SC injection, i.e. any rule one would apply to be able to predict the dose-dependent effects, given the faster absorption rate and increased bioavailability....