Are there prescription medicines I should avoid if I am taking beta blockers?

There are several medications that are contraindicated, should be avoided, or require close monitoring if used concomitantly with beta blockers.^1-9

CYP2D6 Enzyme Inhibitor Medications

Concomitant use of CYP2D6 enzyme inhibitors and beta blockers may increase the plasma concentration of beta blockers and may require a decrease in the dose of beta blockers.^5,9-11 People who have poor CYP2D6 metabolism may also experience increased levels of beta blockers when administered together. Examples of CYP2D6 enzyme inhibitors include antidepressants (e.g., fluoxetine, paroxetine, or bupropion), antipsychotics (e.g., thioridazine), antiarrhythmics (e.g., propafenone, quinidine), antiretrovirals (e.g., ritonavir), antihistamines (e.g., diphenhydramine), antimalarials (e.g., hydroxychloroquine, quinidine), antifungals (e.g., terbinafine), and medications for stomach ulcers (e.g., cimetidine¹²).⁸

Hypotensive Agents

People should use caution with concomitant use of catecholamine-depleting drugs and beta blockers as it may increase the risks of hypotension and severe bradycardia.^1-4,7,8,13 These may produce symptoms of vertigo, syncope, or postural hypotension.   Examples include reserpine, monoamine oxidase (MAO) inhibitors, and clonidine.

Calcium Channel Blockers

Concomitant use of calcium channel blockers, specifically verapamil or diltiazem, and beta blockers may result in slowing the heart rate, conduction disturbances, and decreasing blood pressure.^{1-4,6,9,12,14}

Digitalis Glycosides

Both digitalis glycosides and beta blockers slow atrioventricular (AV) conduction¹⁴ and their concomitant use can increase the risk of bradycardia.^1,3,4,9,12 Concomitant use of digitalis glycosides and carvedilol increases digoxin levels^15,16 by about^1,3,4 15% and up to about 30%.²

Antiarrhythmics

Concomitant use of class I antiarrhythmics and beta blockers can increase the effects on AV-conduction. Concurrent use with antiarrhythmics such as amiodarone may increase beta blocker levels^17,18 and result in a slow heart rate or cardiac conduction.^1,3,4,6,19 The use of disopyramide with beta blockers have been associated with severe bradycardia, asystole, and heart failure.^13,14

Insulin and Oral Hypoglycemics

Concomitant use of insulin or oral hypoglycemic and beta blockers may enhance hypoglycemic action.^1-4,14,19 Beta blockers can also mask hypoglycemia signs and symptoms when used with antidiabetic medications.^5,20

Rifampin

Concomitant use of rifampin, an enzyme inducer, and beta blockers can reduce plasma concentrations.²¹  Concurrent administration with carvedilol may decrease carvedilol levels^5,22 by up to 70% by upregulating carvedilol intestinal secretion.²³ It can also enhance hepatic clearance of propranolol and require an increase in beta blocker dosage.¹⁹

Cyclosporine

Concomitant use of cyclosporine and carvedilol increases cyclosporine levels, and about a 20% reduction in cyclosporine dose is recommended.^1-4,24-26 

^References

1. APO-Carvedilol [package insert]. Toronto, Canada: Apotex Pharmaceutical Holdings Inc.; 2015.
2. Auro-Carvedilol [package insert]. Ontario, CA: Aurobindo Pharma Inc.; 2013.
3. Coreg [package insert]. Ciales, PR: GK Pharmaceuticals Contract Manufacturing Operations; 2008.
4. Coreg CR [package insert]. Ciales, PR: GK Pharmaceuticals Contract Manufacturing Operations; 2008.
5. Vanderhoff BT, Ruppel HM, Amsterdam PB. Carvedilol: the new role of beta blockers in congestive heart failure. Am Fam Physician. 1998;58(7):1627-1634, 1641-1622.
6. Tenormin [package insert]. Conovanas, PR: AstraZeneca Pharmaceuticals LP; 2011.
7. Metoprolol succinate extended-release tablets [package insert]. Sodertalje, Sweden: AstraZeneca AB; 2006.
8. Lopressor [package insert]. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2008.
9. Bystolic [package insert]. St. Louis, MO: Forest Pharmaceuticals; 2011.
10. Samer CF, Lorenzini KI, Rollason V, Daali Y, Desmeules JA. Applications of CYP450 testing in the clinical setting. Mol Diagn Ther. 2013;17(3):165-184.
11. Lymperopoulos A, McCrink KA, Brill A. Impact of CYP2D6 genetic variation on the response of the cardiovascular patient to carvedilol and metoprolol. Curr Drug Metab. 2015;17(1):30-36.
12. Trandate [package insert]. Oakville, ON: Prometheus Laboratories Inc.; 2010.
13. Tenormin Injection [package insert]. Conovanas, PR: AstraZeneca Pharmaceuticals LP; 2016.
14. Brodde OE, Kroemer HK. Drug-drug interactions of beta-adrenoceptor blockers. Arzneimittel-Forschung. 2003;53(12):814-822.
15. De Mey C, Brendel E, Enterling D. Carvedilol increases the systemic bioavailability of oral digoxin. Br J Clin Pharmacol. 1990;29(4):486-490.
16. Wermeling DP, Field CJ, Smith DA, Chandler MH, Clifton GD, Boyle DA. Effects of long-term oral carvedilol on the steady-state pharmacokinetics of oral digoxin in patients with mild to moderate hypertension. Pharmacotherapy. 1994;14(5):600-606.
17. Horiuchi I, Kato Y, Nakamura A, Ishida K, Taguchi M, Hashimoto Y. Inhibitory and stimulative effects of amiodarone on metabolism of carvedilol in human liver microsomes. Bio Pharm Bull. 2010;33(4):717-720.
18. Fukumoto K, Kobayashi T, Komamura K, Kamakura S, Kitakaze M, Ueno K. Stereoselective effect of amiodarone on the pharmacokinetics of racemic carvedilol. Drug Metab Pharmacokinet. 2005;20(6):423-427.
19. Blaufarb I, Pfeifer TM, Frishman WH. beta-blockers. Drug interactions of clinical significance. Drug Saf. 1995;13(6):359-370.
20. Frishman WH. Carvedilol. N Engl J Med. 1998;339(24):1759-1765.
21. Riddell JG, Harron DW, Shanks RG. Clinical pharmacokinetics of beta-adrenoceptor antagonists. An update. Clin Pharmacokinet. 1987;12(5):305-320.
22. Keating GM, Jarvis B. Carvedilol. Drugs. 2003;63(16):1697-1741.
23. Giessmann T, Modess C, Hecker U, et al. CYP2D6 genotype and induction of intestinal drug transporters by rifampin predict presystemic clearance of carvedilol in healthy subjects. Clin Pharmacol Ther. 2004;75(3):213-222.
24. Amioka K, Kuzuya T, Kushihara H, Ejiri M, Nitta A, Nabeshima T. Carvedilol increases ciclosporin bioavailability by inhibiting P-glycoprotein-mediated transport. J Pharm Pharmacol. 2007;59(10):1383-1387.
25. Bader FM, Hagan ME, Crompton JA, Gilbert EM. The effect of beta-blocker use on cyclosporine level in cardiac transplant recipients. J Heart Lung Transplant. 2005;24(12):2144-2147.
26. Kaijser M, Johnsson C, Zezina L, Backman U, Dimeny E, Fellstrom B. Elevation of cyclosporin A blood levels during carvedilol treatment in renal transplant patients. Clin Transplant. 1997;11(6):577-581.