also toxicity, since phenyltropanes are highly versatile. for more examples of interesting phenyltropanes, see some of the more recent patents, e.g. u.s. patent 6,329,520, u.s. patent 7,011,813, u.s. patent 6,531,483, and u.s. patent 7,291,737. potency in vitro should not be confused with the actual dosage, as pharmacokinetic factors can have a dramatic influence on what proportion of an administered dose actually gets to the target binding sites in the brain, and so a drug that is very potent at binding to the target may nevertheless have only moderate potency in vivo. for example, rti-336 requires a higher dosage than cocaine. accordingly, the active dosage of rti-386 is exceedingly poor despite the relatively high ex vivo dat binding affinity. sister substances many molecular drug structures have exceedingly similar pharmarcology to phenyltropanes, yet by certain technicalities do not fit the phenyltropane moniker. these are namely classes of dopaminergic cocaine analogues that are in the piperidine class (a category that includes methylphenidate) or benztropine class (such as difluoropine: which is extremely close to fitting the criteria of being a phenyltropane.) whereas other potent dris are far removed from being in the phenyltropane structural family, such as benocyclidine or vanoxerine. see: list of cocaine analogues most any variant with a tropane locant—3-β (or α) connecting linkage differing from, e.g. longer than, a single methylene unit (i.e. "phenyl"), including alkylphenyls (see the styrene analog, first image given in example below) is more correctly a "cocaine analogue" proper, and not a phenyltropane. especially if this linkage imparts a sodium channel blocker functionality to the molecule: more cocaine analogue examples