Objective: We have shown that the administration of 0.8 mg/kg of morphine (M) to patients with COPD resulted in a 20% increase in the maximum oxygen consumption (Vo2max), but was associated with significant drowsiness and euphoria. The objective of the present study was to ascertain whether lower doses of M alone or in combination with prochlorperazine (PC) or promethazine (P) could elicit significant increases in exercise tolerance.
Design: The exercise capacity, psychological status, and reaction times were assessed before and 60 min after the patients received placebo (PLAC), 30 mg M orally, 30 mg M plus 10 mg PC (M-PC), or 30 mg M plus 25 mg P (M-P) in a randomized double-blind crossover study. In a secondary study, nine patients were tested on three separate days before and after receiving PLAC, 25 mg P, or 30 mg M plus 25 mg P.
Patients: Seven COPD patients (FEV1=0.99 +/- 0.30 L, Vo2max=990 +/- 315 mL/min) who were ventilatory-limited.
Setting: Veterans Affairs medical center.
Results: After the patients ingested M-P, the increase in the Vo2max (129.0 +/- 104 mL/min), the workload (10.0 +/- 6.5 W) and the maximum minute ventilation (4.0 +/- 3.9 L/min) were significantly greater (p<0.05) than after PLAC ingestion (-4.8 +/- 79 mL/min, 1.4 +/- 6.9 W, and -1.6 +/- 2.4 L/min, respectively). Changes after the ingestion of M, P, o r M-PC were intermediate. The M-PC combination adversely affected the patient's reported mental status (Bond visual analog scale) more than the M-P or M regimens. No regimen significantly affected the reaction time.
Conclusions: We conclude that the administration of 30 mg of M plus 25 mg of P significantly improves the exercise tolerance of patients with COPD, without significantly impairing the mental capabilities of the subjects. The utility of this regimen over longer time periods needs to be evaluated.