were obtained from Sigma,
absolute ethanol was obtained from Panreac, and 4-methylpyrazole-
HCl (4-MP) was purchased from Aldrich. Alprazolam, cimetidine,
flunitrazepam and tramadol, were kindly provided by the
Department of Toxicology of the National Institute of Legal Medicine
– South Branch (Lisbon, Portugal). All other chemicals and reagents
used were of analytical grade.