To : Catherine Mallon Re : Cocaine use and Breastfeeding The question "Should a drug abuser breastfeed" always seems to get me into trouble with some of my colleagues. I'll let each of you answer this for yourself, but I will answer the kinetics part of this question, as I seem to get this question every week. It is true that cocaine has a very brief half-life (0.8 to 1.3 hr) in the plasma compartment, after which it is rapidly metabolized to benzoecgonine (about 50%) which is inactive. Plasma Cocaine may be detectible for up to 4-6 hours at rather "minimal" levels, as it is slowly released from peripheral binding sites. The benzoecgonine metabolite (inactive) has a much longer half-life, about 5-7 hours in adults. Interestingly, it is the metabolite that the urine screens detect, as cocaine itself is only detectible in urine for up to 8 hours, but benzoecgonine is detectible( in adults ) for up to 144 hours, and maybe many times this in neonates (weeks). So if you're asked this question, "When can I breastfeed", I generally answer "after 24 hours". This also allows for elimination of any other medication she may have coingested. But I also inform the mother that her infant may be "Drug Screen Positive" for cocaine for weeks as benzoecgonine probably transfers into milk in small levels for long periods (perhaps >144 hrs), and that this may have legal complications if her infant 'tests positive'. This is certainly so for other medications such as marijuana, PCP, etc, which can transfer via milk to the infant in high enough concentrations that the infant's urine is drug screen positive for long periods. Although the metabolite (benzoecgonine) may not be active, the police don't seem to discriminate this factor. Regards Tom Hale