Stimulants such as the amphetamines
and cocaine have been reported to enhance
narcotic analgesia while reducing
drowsiness. Dextroamphetamine, for
example, has been shown to potentiate the
analgesic effect of morphine in postoperative
pain (69). Cocaine was first used in
combination with morphine by Snow (70)
in the Brompton's mixture that contains a
fixed dose of the drug. Because tolerance
to the stimulant effects of these drugs
develops rapidly, their usefulness appears
limited (26). The stimulant effects of these
drugs and the sedative effects of the
phenothiazines are mutually antagonistic