A stimulant compound associated with methylphenidate is 4-Methylmethylphenidate, 4-MMPH or threo-4-Methylmethylphenidate (4-MeTMP, 4-MMPH). It is slightly less effective than methylphenidate and, considering its strong binding affinity, has relatively low effectiveness in preventing dopamine reuptake, which contributed to its investigation as a potential replacement medication for stimulant addiction treatment (cf. nocaine). On the other hand, several other simple ring-substituted threo-methylphenidate derivatives, such as 4-fluoro and 3-chloro compounds, are both more potent in their effectiveness as dopamine reuptake inhibitors and in animal drug discrimination assays than methylphenidate.