Decreased EEG sensitivity to alprazolam in subjects with a parental history of alcoholism

GABA-benzodiazepine receptor function in alcohol dependence: a combined 11C-flumazenil PET and pharmacodynamic study

RATIONALE

Gamma-aminobutyric acid (GABA)-benzodiazepine receptor function is hypothesised to be reduced in alcohol dependence.

OBJECTIVES

We used positron emission tomography (PET) with [11C]flumazenil, a non-selective tracer for brain GABA-benzodiazepine (GABA-BDZ) receptor binding, to determine in vivo the relationship between BDZ receptor occupancy by an agonist, midazolam, and its functional effects.

METHODS

Abstinent male alcohol dependent subjects underwent [11C]flumazenil PET to measure occupancy of BDZ receptors by midazolam whilst recording its pharmacodynamic effects on behavioural and physiological measures. Rate constants describing the exchange of [11C]flumazenil between the plasma and brain compartments were derived from time activity curves.

RESULTS

A 50% reduction in electroencephalography (EEG)-measured sleep time was seen in the alcohol dependent group despite the same degree of occupancy by midazolam as seen in the control group. The effects of midazolam on other measures of benzodiazepine receptor function, increasing EEG beta1 power and slowing of saccadic eye movements, were similar in the two groups. No differences in midazolam or flumazenil metabolism were found between the groups.

CONCLUSIONS

In summary, our study suggests that alcohol dependence in man is associated with a reduced EEG sleep response to the benzodiazepine agonist, midazolam, which is not explained by reduced BDZ receptor occupancy, and is consistent with reduced sensitivity in this measure of GABA-BDZ receptor function in alcohol dependence. The lack of change in other functional measures may reflect a differential involvement of particular subtypes of the GABA-BDZ receptor.

Safety and Efficacy of GABAergic Medications for Treating Alcoholism

This article highlights the proceedings of a symposium presented at the 27th Annual Scientific Meeting of the Research Society on Alcoholism in Vancouver, British Columbia, Canada, June 29, 2004. The organizers and co-chairs were Bankole A. Johnson, MD, PhD, and Robert M. Swift, MD, PhD. The presentations included (1) Introduction, by Bankole A. Johnson; (2) Safety, Tolerability, and Efficacy of gamma-Hydroxybutyric Acid and Baclofen in the Treatment of Alcohol Addiction, by Giovanni Addolorato; (3) Safety of Gabapentin in Treating Alcoholism, by Hugh Myrick; (4) New Data on the Safety and Effectiveness of Topiramate in the Treatment of Alcohol Dependence, by Bankole A. Johnson; (5) Evaluating the Risk of Benzodiazepine Prescription to Alcohol-Dependent Individuals, by Domenic A. Ciraulo; and (6) Safety and Efficacy of GABAergic Agents in Treating Alcoholics: Discussion, by Robert M. Swift.