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A half-life is defined as the time required for the drug concentration in the blood to be reduced by 50%, provided no additional drug absorption occurs during the decline. Below are the estimated half-lives of various Parkinson medications: Sinemet: Mean time to peak concentration was 0.5 hours Sinemet CR: Mean time to peak concentration was 2 hours Eldepryl: The drug is rapidly metabolized. Three metabolites, N-desmethyldeprenyl (the major metabolite; mean half-life 2 hours), amphetamine (mean half-life 17.7 hours), and methamphetamine (mean half-life 20.5 hours), were found in serum and urine. Permax: 24 hours Parlodel: 8-12 hours Mirapex: 8-12 hours Requip: 6 hours Dominic Marchese, RPh. Athena Rx Home Pharmacy 1-800-5-ATHENA ----- Original Message ----- From: Ivan M Suzman <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, September 15, 1999 8:34 AM Subject: What is the "Half-life" of a medication? > On Sun, 12 Sep 1999 20:01:32 -0700 "J. R. Bruman" <[log in to unmask]> > writes: > > "Because cabergoline seems to have much fewer nasty side effects than > bromocriptine, and especially since its half-life of 65 hours permits > Parkinson's sufferers to sleep all night through," > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > ^^^^^^^^^^^^^^^^^^^^ > Hi from Maine to J.R., Brian, and everyone- > > Can we please come to a consensus about the meaning of the term, > "half-life" ? Knowing what a half-life is could be of IMMENSE help in > planning our daily medicaiton routines! > > I understand it to mean the usual time that elapses from the point that a > > medication takes effect, until that at which half of the medication has > been used up. Am I close? > > Is this purely based on chem-lab analysis, or also on REAL human > beings whose responses to a drug are closely monitored? > > What are thought to be the half-lives of some of the more convential > PD drugs, like sinemet, madopar, sinemet CR, and selegeline? > > Best regards, > > Ivan > > > ^^^^^^ WARM GREETINGS FROM ^^^^^^^^^^^^ :-) > Ivan Suzman 49/39/36 [log in to unmask] :-) > Portland, Maine land of lighthouses 60 deg. F :-) > ********************************************************************