Design and validation of an improved nonferrous smoking device for self-administration of smoked drugs with concurrent fMRI neuroimaging.

Several popularly abused drugs, such as nicotine (tobacco) and THC (delta9-tetrahydrocannabinol) (marihuana) are commonly self-administered by the smoked route. Although the neuronal substrates mediating the effect of smoked drugs are of interest, studies of their acute actions in living human brain has been difficult due to the unique constraints imposed by neuroimaging equipment and scanning environments. We have previously reported a device for the self-administration of smoked drugs with concurrent blood oxygen level dependent (BOLD) fMRI imaging. Here we report improvements to the device which result in improved drug delivery to the smoker. Gas chromatography/mass spectrometry (GCMS) analysis of nicotine recovered from filter extracts revealed that the amount of nicotine delivered to subjects smoking with our original device was reduced by approximately 44% compared to nicotine delivered by cigarettes smoked normally. Improvements were made to the smoke delivery component of our apparatus in an attempt to improve drug delivery, while not interfering with collection of MRI data. Nicotine plasma levels in 9 subjects smoking both with and without the improved smoking device in the laboratory were not significantly different. Similarly, the device produced no significant difference in either ratings of the subjective effects of nicotine, or changes in cardiovascular parameters in this experiment. The improved device does not interfere with typical drug effects produced by normal smoking. Phantom scans revealed that BOLD signal was not found to be altered by the (in-bore) installation and operation of the improved device. Preliminary data analysis of smoking induced changes in the BOLD response to visual stimulation suggest that this response is not affected by the improved device, the act of smoking, air puffing, nicotine, or other components of cigarette smoke. The improved device does not interfere with the collection of MRI neuroimaging data. Use of this device will facilitate investigations of the acute neuronal effects of smoked drugs.