Modification of cardiopressor and respirogenic effects of doxapram by propranolol.

The respiratory stimulant doxapram hydrochloride has long been shunned in the United States because of a perpetuated fear of the alleged side effects of hypertension and tachycardia with attendant hypermetabolism and increased oxygen consumption. This study reports the results of the administration of doxapram alone, and of doxapram in conjunction with the beta-blocker propranolol on the blood pressure, heart rate, and respiratory rate of 12 healthy unanesthetized volunteer subjects. Results showed an augmentation in blood pressure (especially diastolic), a significant decrease in heart rate, and an unexpected actual increase in respiratory rate in the doxapram/propranolol group. Subtleties of sympathetic balance, as well as proposed future studies are discussed.