Propranolol on tests of visual function and central nervous activity.

TLDR: It is perhaps surprising that changes in noradrenaline were comparable to those of adrenaline, but stress appears to increase the excretion of both catecholamines (Levi, 1968), which is likely to provide the more useful measurement of pain.

Abstract: Measurement of the excretion of catecholamines appears to provide an indirect but objective measure of pain which may be useful in the assessment of analgesic drugs. There is a large individual variation and the method is likely to be useful only in crossover trials when the patient provides his own control. The differences in treated and untreated patients are not large and urine collections for at least three days are likely to be required to detect them. In a previous experiment, there were no significant differences in treated and untreated patients with urine collected for three 12 h periods overnight. In this study, a variety of treatments was used and in all cases there was a good response to treatment. Less marked pain relief might be undetectable or require longer periods of collection. The findings of this study could also be explained by a direct action of analgesic and anti-inflammatory drugs on some aspect of catecholamine metabolism, which must be considered when the method is applied to individual compounds. It is perhaps surprising that changes in noradrenaline were comparable to those of adrenaline, but stress appears to increase the excretion of both catecholamines (Levi, 1968). Because noradrenaline is excreted in much larger amounts, it is likely to provide the more useful measurement of pain.