Phenylephrine Metoprolol

Acebutorol, arotinolol, atropine, bupivacaine, clorprenaline, denopamine, eperisone, epinastine, etirefline, fenoterol, homatropine, ketamine, metanephrine, metoprolol, mexiletine, nicardipine, oxyphencyclimine, phenylephrine, pindolol, primaquine, promethazine, sulpiride, ter-butaline, tolperizone, trihexyphenidyl, trimebutine, trimetoquinol, trimipramine, verapamil 81... 

Clinically important, potentially hazardous interactions with albuterol, alpha-blockers, amitriptyline, amoxapine, atenolol, beta-blockers, carteolol, chlorpromazine, clomipramine, cocaine, desipramine, doxepin, ephedra, ergotamine, furazolidone, halothane, imipramine, insulin detemir, MAO inhibitors, metoprolol, nadolol, nortriptyline, oxprenolol, penbutolol, phenelzine, phenoxybenzamine, phenylephrine, pindolol, prazosin, propranolol, protriptyline, sympathomimetics, terbutaline, thioridazine, timolol, tranylcypromine, tricyclic antidepressants, trimipramine, vasopressors... 

Noninterfering acetaminophen, acetylmorphine, amiodarone, amobarbital, amphetamine, bendroflumethiazide, benzocaine, benzoylecgonine, benzthiazide, butalbital, carbamaze-pine, chlorothiazide, clonazepam, cocaine, codeine, cotinine, cyclosporine, cyclothiazide, desalkylflurazepam, diamorphine, dicumerol, ephedrine, ethaciynic acid, ethanol, eth-chlorvynol, ethosuximide, furosemide, glutethimide, hydrochlorothiazide, hydrocodone, hydroflumethiazide, hydromorphone, lorazepam, mephentermine, meprobamate, meth-amphetamine, metharbital, methoxsalen, methoxyphenteramine, methsuximide, meth-ylcyclothiazide, metoprolol, MHPG, monoacetylmorphine, morphine, normethsuximide, oxazepam, oxycodone, oxymorphone, pentobarbital, phencyclidine, phenteramine, phenylephrine, phenytoin, polythiazide, primidone, prochlorperazine, salicylic acid, sulfanilamide, THC-COOH, theophylline, thiazolam, thiopental, thioridazine, tocainide, trichlo-romethiazide, trifluoperazine, valproic acid, warfarin... 

Effects on blood pressure and heart rate The hypertensive effects of adrenaline (epinephrine) can be markedly increased in patients taking non-selective beta blockers such as propranolol. A severe and potentially life-threatening hypertensive reaction and/or marked bradycardia can develop. Cardioselective beta blockers such as atenolol and metoprolol interact minimally. An isolated report describes a fatal hypertensive reaction in a patient given propranolol and phenylephrine, but concurrent use normally seems to be uneventful Paradoxically, marked hypotension occurred in one patient given low-dose carvedilol and dobutamine. Anaphylaxis Some evidence su ests that anaphylactic shock in... 

However, no change in blood pressure was seen in a study in both nor-motensive subjects and patients taking metoprolol who were given 0.5 to 4-mg doses of phenylephrine intranasally every hour, to a total of 7.5 to 15 mg (4 to 30 times the usual dose). Similarly, in a placebo-controlled study in 12 hypertensive patients, neither propranolol nor metoprolol significantly altered the dose of intravenous phenylephrine required to cause a 25 mmHg increase in systolic blood pressure. 

Adrenaline (epinephrine) stimulates alpha- and beta-receptors of the cardiovascular system, the former results in vasoconstriction (mainly alphaj) and the latter in both vasodilatation (mainly beta2) and stimulation of the heart (mainly betaj). The net result is usually a modest increase in heart rate and a small rise in blood pressure. However, if the heta-reeeptors are blocked by a non-selective beta blocker, such as propranolol or nadolol (see Table 22.1 , (p.833) for a list), the unopposed alpha vasoeonstrietion causes a marked rise in blood pressure, followed by reflex bradyeardia. Cardioselective beta blockers such as atenolol and metoprolol, whieh are more selective for betaj receptors, do not prevent the vasodilator aetion of adrenaline at beta2 receptors to the same extent, and therefore the effect of any interaction is relatively small. Consequently, adrenaline has been used to assess the degree of beta blockade produced by propranolol and other beta blockers.Phenylephrine is largely an alpha stimulator, therefore beta blockers should have a minimal effect on its action. 

---