TY - JOUR
T1 - Enhanced sensitivity to benzodiazepines in active cocaine-abusing subjects
T2 - A pet study
AU - Volkow, Nora D.
AU - Wang, Gene Jack
AU - Fowler, Joanna S.
AU - Hitzemann, Robert
AU - Gatley, Samuel J.
AU - Dewey, Stephen S.
AU - Pappas, Naomi
PY - 1998
Y1 - 1998
N2 - Objective: Because cocaine enhances dopamine brain activity and dopamine signals are transferred through γ-aminobutyric acid pathways, the authors hypothesized GABA-ergic disruption in cocaine-abusing subjects. This study tests this hypothesis. Method: GABA brain function was assessed indirectly by measuring the brain metabolic responses to lorazepam, a drug that facilitates GABA neurotransmission. Thirteen current cocaine-abusing subjects and 14 comparison subjects were scanned twice with positron emission tomography and [18F]fluorodeoxyglucose; the first scan was obtained after placebo administration and the second after lorazepam administration (30 μg/kg). Results: Despite significantly higher plasma lorazepam concentrations in comparison subjects than in cocaine-abusing subjects, lorazepam-induced decrements in whole brain metabolism were significantly greater in cocaine- abusing (mean=21%, SD=13%) than in comparison (mean=13 %, SD=7%) subjects. These differences were largest in striatum, thalamus, and parietal cortex. Lorazepam-induced sleepiness in cocaine-abusing subjects was intense and was significantly greater than in comparison subjects, and it was correlated with lorazepam-induced changes in thalamic metabolism. Whereas regional metabolic measures during placebo administration were significantly higher in cocaine- abusing subjects than in comparison subjects, the measures during lorazepam administration were equivalent for both groups. Conclusions: The enhanced sensitivity to lorazepam in cocaine-abusing subjects suggests disruption of GABA pathways that may reflect, in part, cocaine withdrawal. The intense sleepiness induced by lorazepam in some of the abusers, despite their significantly lower plasma concentrations, should alert clinicians of the potential toxicity from accentuated responses to sedative hypnotics in active cocaine-abusing subjects.
AB - Objective: Because cocaine enhances dopamine brain activity and dopamine signals are transferred through γ-aminobutyric acid pathways, the authors hypothesized GABA-ergic disruption in cocaine-abusing subjects. This study tests this hypothesis. Method: GABA brain function was assessed indirectly by measuring the brain metabolic responses to lorazepam, a drug that facilitates GABA neurotransmission. Thirteen current cocaine-abusing subjects and 14 comparison subjects were scanned twice with positron emission tomography and [18F]fluorodeoxyglucose; the first scan was obtained after placebo administration and the second after lorazepam administration (30 μg/kg). Results: Despite significantly higher plasma lorazepam concentrations in comparison subjects than in cocaine-abusing subjects, lorazepam-induced decrements in whole brain metabolism were significantly greater in cocaine- abusing (mean=21%, SD=13%) than in comparison (mean=13 %, SD=7%) subjects. These differences were largest in striatum, thalamus, and parietal cortex. Lorazepam-induced sleepiness in cocaine-abusing subjects was intense and was significantly greater than in comparison subjects, and it was correlated with lorazepam-induced changes in thalamic metabolism. Whereas regional metabolic measures during placebo administration were significantly higher in cocaine- abusing subjects than in comparison subjects, the measures during lorazepam administration were equivalent for both groups. Conclusions: The enhanced sensitivity to lorazepam in cocaine-abusing subjects suggests disruption of GABA pathways that may reflect, in part, cocaine withdrawal. The intense sleepiness induced by lorazepam in some of the abusers, despite their significantly lower plasma concentrations, should alert clinicians of the potential toxicity from accentuated responses to sedative hypnotics in active cocaine-abusing subjects.
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M3 - Article
C2 - 9464198
AN - SCOPUS:0031882806
SN - 0002-953X
VL - 155
SP - 200
EP - 206
JO - American Journal of Psychiatry
JF - American Journal of Psychiatry
IS - 2
ER -