> The phrase "...throw in another for good measure" is a fundamental >concept that turns scientifically based recommendations into advice. Ooh, good point, Nikki, thank you for catching that. > Now, another question. I have used the five half-lives rule because I >have learned it from physicians. Does anyone know where the evidence for it >comes from? As I understand it, after 1 half-life, 50% of the drug remains. After 2, 25%. After 3, 12.5%, after 4, 6.25%. And after 5, only 3.125% remains, so the blood (and milk) should be 97% drug-free. But why do we choose that instead of 93.75% drug-free at 4 half-lives? Or 87.5% drug-free at 3? We're talking about a continuum of extremely low amounts anyway. We probably should be tailoring the number of half-lives we wait to the level of concern we have about the drug; barring that kind of expertise, "5 half-lives" is probably amply cautious for them all. But people tend to be especially squeamish about chemo meds, so when I argue on behalf of continuing to nurse through chemo, I've tended to offer an *extra extra caution* option. Wait 6 half-lives and you're 98.4% drug-free. Wait 7 and you're 99.2% drug-free and how could *anyone* object? So my unscientific point was, be cautious, be extra-extra cautious if you like, and you *still* won't have to suspend nursing for very long. Frank Nice or others, any comments? Diane Wiessinger, MS, IBCLC Ithaca, NY www.wiessinger.baka.com *********************************************** The LACTNET mailing list is powered by L-Soft's renowned LISTSERV(R) list management software together with L-Soft's LSMTP(TM) mailer for lightning fast mail delivery. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html