Discrimination of intranasal cocaine

In the development of medications for the treatment of cocaine abuse, the drug discrimination paradigm can be used to identify medications that can attenuate the discriminative stimulus effects of cocaine. To ascertain that participants are basing the discrimination on the drug's central effects, this paradigm requires that the drug and placebo administrations do not produce any peripheral effects on which the discrimination can be based. This study examined whether intranasal cocaine (50 mg) can be discriminated from placebo (46 mg lactose + 4 mg cocaine), how quickly this discrimination can be made, and whether pretreatment with intranasal benzocaine can affect this discrimination. Results showed that subjects were generally able to discriminate the drug conditions correctly 15 s after administration, and this was unaffected by benzocaine. These results suggest that subjects base the discrimination on peripheral drug effects (e.g. taste) that are not affected by anaesthesia of the nasal passage, and that the intranasal route of cocaine administration is unlikely to be feasible with a drug discrimination paradigm.