THE VASOCONSTRICTOR AND PRESSOR EFFECTS OF OCTINUM, MEDIATED BY ITS ALPHA-ADRENERGIC ACTION, MAY BE ENHANCED BY THE CONCOMITANT ADMINISTRATION OF DRUGS WITH SIMILAR EFFECTS, SUCH AS ERGOT ALKALOIDS OR OXYTOCIN. SEVERE HYPERTENSION MAY ALSO DEVELOP IF OCTINUM IS GIVEN WITH A BETA BLOCKER SINCE THE BETA BLOCKER OPPOSES THE BETA ADRENERGIC ACTION OF OCTINUM. ADMINISTRATION OF OCTINUM OR NORADRENALINE WITH TRICYCLIC ANTIDEPRESSANTS CARRIES A RISK OF INDUCING HYPERTENSION AND ARRHYTHMIAS. THE ACTION OF OCTINUME MAY BE ONLY SLIGHTLY ENHANCED BY AN MAOIS. THE HYPOKALAEMIC EFFECT OF OCTINUM MAY BE POTENTIATED BY OTHER DRUGS THAT CAUSE POTASSIUM LOSS, INCLUDING CORTICOSTEROIDS, POTASSIUM-DEPLETING DIURETICS. MAOIS PRODUCE SEVERE HYPERTENSIVE REACTION. THE VASOCONSTRICTOR AND PRESSOR EFFECTS OF ADRENALINE, MEDIATED BY ITS ALPHA-ADRENERGIC ACTION, MAY BE ENHANCED BY THE CONCOMITANT ADMINISTRATION OF DRUGS WITH SIMILAR EFFECTS, SUCH AS ERGOT ALKALOIDS OR OXYTOCIN. SEVERE HYPERTENSION MAY ALSO DEVELOP IF ADRENALINE IS GIVEN WITH A BETA BLOCKER SINCE THE BETA BLOCKER OPPOSES THE BETA ADRENERGIC ACTION OF ADRENALINE. ADMINISTRATION OF ADRENALINE OR NORADRENALINE WITH TRICYCLIC ANTIDEPRESSANTS CARRIES A RISK OF INDUCING HYPERTENSION AND ARRHYTHMIAS. THE ACTION OF ADRENALINE OR NORADRENALINE MAY BE ONLY SLIGHTLY ENHANCED BY AN MAOIS. THE HYPOKALAEMIC EFFECT OF ADRENALINE MAY BE POTENTIATED BY OTHER DRUGS THAT CAUSE POTASSIUM LOSS, INCLUDING CORTICOSTEROIDS, POTASSIUM-DEPLETING DIURETICS. USE OF EPINEPHRINE WITH EXCESSIVE DOSES OF DIGITALIS, MERCURIAL DIURETICS, OR OTHER DRUGS THAT SENSITIZE THE HEART TO ARRHYTHMIAS IS NOT RECOMMENDED. THE EFFECTS OF EPINEPHRINE MAY BE POTENTIATED BY TRICYCLIC ANTIDEPRESSANTS; CERTAIN ANTIHISTAMINES, E.G., DIPHENHYDRAMINE, TRIPELENNAMINE, D-CHLORPHENIRAMINE; AND SODIUM L-THYROXINE. PHENOTHIAZINES HAVE SOME ALPHA-ADRENERGIC BLOCKING ACTIVITY AND MAY REDUCE THE PRESSOR EFFECTS AND DURATION OF ACTION OF PHENYLEPHERINE. ADRENALINE & OTHER POTENT BETA-1 AGONISTS SHOULD NOT BE USED CONCOMITANTLY BECAUSE OF SYNERGISTIC HYPERTENSIVE EFFECT.