Doctor insights on:
Drug Half Life
Taking a short half-life drug(venlafaxine) at bed time
does waste it?I think 150mg at morning is better than 75mg morning&bed time.
Not wasted: The effects of antidepressants don't depend on their elimination half-lives. Long term changes occur in cells as a result of ongoing exposure to the med. Half-life issues have more to do with immediate side-effects. That said, venlafaxine (effexor) is usually prescribed in time-release versions ("xr") now, to spread absorption over the day. In this case either dosing approach is similar. ...Read more
Does 50 mg of modafinil(half of prescribed dose) is effective for drowsiness?.Drug tolerance chance?.Elimination half life?I will start tomorrow.
Dose may be low: The dose maybe somewhat low. Comes in 50s, 150s and 250 in the us. The half-life is 12 to 15 hours. I do not generally encounter tolerance developing to this medication. The only exception to that rule might be someone with idiopathic central nervous system hypersomnolence. Best wishes and i hope that this does a good job working on your hypersomnolence. Take care. ...Read more
Once a drug is taken, does it take about twice as long as its half-life to lose effect or be completely excreted from your body, whichever is faster?
Can u explain little about what a half life of a drug is? And how it works,I think the longer the life the longer it stays in ur system hmm?
It: Half life is a video game. In relation to drugs it is the time it takes for a drug to become half of what it was and gives informaton on how long it is in your body. Good luck ...Read more
See below: Half-life means how long it takes for half of the remaining substance to degrade or be cleared from the system. So if you have 1g, then during the 1st half-life, 500 mg is gone. You're left with 500 mg. After the 2nd half-life, 250 mg is gone, leaving 250 mg, and so on. ...Read more
50%: By definition, the 1/2 life of a drug is when 50% of the active drug is eliminated from the body by excretion, metabolism or inactivation. This value is important to allow adjustment of dosage to keep therapeutic levels at the proper level. For instance if a drug is eliminated in the urine, and you have some degree of kidney failure, the 1/2 life is longer so lower the dosage. ...Read more
Do psychiatric drugs have metabolites that stay on your body. Do they have an affect after all the half life is over?
Some do, some don't: Many different medications are used in psychiatry. Some have "active metabolites" and some don't. Generally speaking, newer meds are less likely to have active metabolites. Another issue: the effect of some meds persists even after the med is gone. For example, antidepressants take a couple weeks to start working — and also a couple weeks to stop, even after they are no longer taken. ...Read moreSee 1 more doctor answer
Valium-If the half life is up to 100 hours, but peak plasma is 1-1.5 hours, but the drug is effective for 6 hours. Please explain these relationships.
Valium metabolism: Valium, a benzodiazepine, t1/2 is 20-70h. That's a wide range. Time to onset (oral route) is 30 - 90 minutes. has active metabolites, so there are actually two peak plasma times. Active metabolites also cause it to be effective longer.Do note, however, that 1/2 life tells us how long it will take for drug to reach steady state & for 1/2 diazepam 2 b cleared, but not about active metabolites. ...Read more