Beta Blockers

Mechanism of Action

  • Blocks beta-receptors of the sympathetic nervous system
  • Some agents act primarily on beta receptors in the heart
    • these are called cardioselective
  • Beta- blockage results in decreased heart rate, blood pressure, and contractility of the heart
    • thereby reducing the demand for oxygen by the heart

Treatment

  • High blood pressure (hypertension)
  • Chest pain (angina pectoris)
  • Abnormal heart rhythms (arrhythmias)
    • Fast heart rates called tachycardia
    • Irregular rhythms like atrial fibrillation
  • Migraine headaches
  • Previous MI patients
    • Reduce the risk of death after a heart attack
  • Glaucoma, Ocular hypertension
    • Eg: Carteolol, Timolol, Betaxolol
  • Anxiety (off-label)

Non-selective Beta Blockers

  • Carteolol (Cartrol, Ocupress, Teoptic, Arteolol, Arteoptic, Calte, Cartéabak, Carteol, Cartéol, Cartrol, Elebloc, Endak, Glauteolol, Mikelan, Poenglaucol, Singlauc)
    • Used to treat glaucoma
    • Also a serotonin 5-HT1A and 5-HT1B receptor antagonist
  • Carvedilol (Coreg)
    • Also decreases peripheral vascular resistance through alpha-1 blockade
  • Labetalol (Normodyne, Trandate)
    • Also decreases peripheral vascular resistance through alpha-1 blockade
  • Nadolol (Norpramin)
  • Oxprenolol (Trasacor, Trasicor, Coretal, Laracor, Slow-Pren, Captol, Corbeton, Slow-Trasicor, Tevacor, Trasitensin, Trasidex)
    • Also exhibits intrinsic sympathomimetic activity
    • Lipophilic beta blocker which more easily passes the blood–brain barrier associated with higher incidence of CNS-related side effects
  • Penbutolol (Levatol, Levatolol, Lobeta, Paginol, Hostabloc, Betapressin)
    • Also exhibits intrinsic sympathomimetic activity
  • Pindolol (Visken)
    • Also exhibits intrinsic sympathomimetic activity
  • Propranolol (Inderal)
  • Sotalol (Betapace, Sotalex, Sotacor, Sotylize)
    • Prescribed only for serious arrhythmias
    • Prolongs QT Interval
  • Timolol (Betimol)
    • Also used to treat glaucoma and ocular hypertension

β1-selective Beta Blockers

  • Acebutolol (Sectral, Prent)
    • Also exhibits intrinsic sympathomimetic activity
    • Lipophilic beta blocker which more easily passes the blood–brain barrier
    • No HDL decrease, unlike most beta blockers
  • Atenolol (Tenormin, Norpramin)
    • Higher risk of type 2 diabetes
  • Betaxolol (Betoptic, Lokren, Kerlone)
    • Also used to treat glaucoma
  • Bisoprolol (Zebeta, Concor)
  • Celiprolol (Cardem, Selectol, Celipres, Celipro, Celol, Cordiax, Dilanorm)
    • Also exhibits intrinsic sympathomimetic activity
  • Metoprolol Succinate (Lopressor, Metolar XR)
    • Long-acting beta-blocker
  • Nebivolol (Bystolic, Nebilet)
    • Decrease peripheral vascular resistance through promoting nitric oxide (NO) release
    • Significantly increases stroke volume while maintaining cardiac output

Effect on Weight

  • Lowered resting metabolic rate (RMR) (Bélanger & Boulay 2005)
  • Weight gain usually occurs in the first few months of treatment (Bélanger & Boulay 2005)
  • Limits the increase in RMR normally observed following aerobic exercise (Bélanger & Boulay 2005)
  • Beta blockers such as Carvedilol don't increase weight gain.

Effect During Rest

  • Decreased resting heart rate (ACSM 2013, Gladson 2011, Niedfeldt 2002)
    • 30-35% reduction (Tesch 1985)
    • Less decrease by intrinsic sympathomimetic activity (ISA) and Beta Blocker (ACSM 2013)
  • Decreased blood pressure (ACSM 2013)
    • Decreased systolic blood pressure (Gladson 2011)
    • Decreased rate pressure product (Gladson 2011)
  • Decreased arrhythmias (ACSM 2013)
    • Decreased ST depression (Gladson 2011)
  • Increased diastolic function (Gladson 2011)
    • Increased myocardial efficiency (Gladson 2011)
  • Increased myocardial oxygen consumption (MVO2) (Gladson 2011)
  • Decreased coronary blood flow (Gladson 2011)
  • Increased diastolic filling time (Gladson 2011)

Effect on Exercise

  • Decreased heart rate during exercise (ACSM 2013, Gladson 2011)
    • Less decrease by cardioselective Beta Blocker (ACSM 2013)
    • 20 to 30% decrease in maximum heart rate (Gladson 2011)
  • Decreased blood pressure (ACSM 2013)
  • Impairment of cardiac output
    • Decrease in cardiac output (Niedfeldt 2002)
    • Decrease or no change in cardiac output (ACSM 2013)
    • 5 to 23% decrease in cardiac output (Gladson 2011)
  • Possible increased stroke volume (Tesch 1985)
    • No effect on stroke volume (Niedfeldt 2002)
    • Increased stroke volume during moderate exercise (Gladson 2011)
  • Impairment of maximum oxygen uptake (Niedfeldt 2002)
    • Decreased acute (single dose) VO2max (ACSM 2013)
      • Decrease of 5-15% (Tesch 1985)
    • Increased chronic VO2max (ACSM 2013, Gladson 2011)
  • Decreased exercise ischemia (ACSM 2013)
    • Decreased ischemic threshold (Gladson 2011)
  • Increase in vascular resistance (Niedfeldt 2002)
  • No effect on plasma volume (Niedfeldt 2002)
  • No effect on muscular strength and power
  • No effect on psychomotor performance
  • Potentially greater ability to perform athletic events requiring high levels of motor control under emotional stress (Tesch 1985)
  • Exercise / Work Capacity
    • Increased exercise capacity (Gladson 2011)
    • Increased exercise capacity
      • Patients with angina (Dreeben-Irimia 2008)
      • Patients with cardiovascular disease (Gladson 2011)
        • Selective β-blockers more than non-selective β-blockers
    • Decreased exercise capacity
      • Patients without angina (Dreeben-Irimia 2008)
      • Patients with hypertension but no cardiovascular disease (Gladson 2011)
    • Impaired work capacity as reflected by the ability to perform intense short term or more prolonged steady-state exercise. (Tesch 1985)
      • Significant decrease in training (Niedfeldt 2002)
      • Exercise performance ability is more greatly impair following a beta 1- and beta 2 receptors (non-selective than beta 1-selective) blockade as opposed to only a beta 1-receptors (beta 1-selective blockers) blockade at equal reductions in heart rate. (Tesch 1985)
  • Increased total exercise time (Gladson 2011)
  • Earlier fatigue and lactate threshold (Niedfeldt 2002)
    • Increase in perceived exertion levels (Niedfeldt 2002)
    • Increase acute (single dose) RPE during exercise.
      • This effect partially subsides with long term treatment (Tesch 1985)
  • Possible exacerbation of exercise-induced bronchospasm or asthma (Niedfeldt 2002)

Metabolic Effects

  • Both selective and non-selective β-blockers disrupt the utilization of fat, glucose, and triglycerides during exercise
    • However, non-selective β-blockers have greater disruptions
      • However, benefits of selective β-blockers are lost at higher doses
  • Greater metabolic disruptions and fatigue occurs at peak plasma concentrations
    • Generally 90 minutes after administration

Nonselective β-blockers

  • Some Nonselective β-blockers may cause adverse effects to the CNS (Gladson 2011)
    • Fatigue
    • Depression
    • Nightmares
  • Thermoregulatory effects during exercise (Gladson 2011)
    • 10% accelerated sweating response
      • Increased risk of dehydration
    • Decreased skin blood flow
      • Peripheral constriction
      • Reduce cardiac output
    • Fluid replacement is important to prevent drop in blood pressure
  • Metabolic effects during exercise (Gladson 2011)
    • Increased fatigue
    • Decreased adipose and intramuscular lipolysis
    • Decreased glycogen breakdown
    • Decreased blood glycogen levels
      • Decreased hepatic glycogenolysis
      • Decreased hepatic gluconeogenesis
      • Possible decrease of glucose utilization by working muscles

Recommendations

  • Exercise same time each day to avoid variations in plasma concentration of β-blockers
  • Take appropriate actions when experiencing any adverse effects of exercise.
  • Patients on Beta-blockers who achieved 65% age-predicted maximal heart rate had a similar adjusted mortality rate as those not on Beta-blockers who achieved 85% age-predicted maximal heart rate (p >0.05) (Hung 2016)

Recommended Populations

  • Recommended to those with coronary artery disease

Populations Not Recommend

  • Not recommended to those with asthma, endurance athletes, collegiate athletes
  • Caution when prescribing some beta-blockers to patients with asthma or bronchospasm

Banned Status

  • Banned in precision sports (ie: shooting, archery, diving, ice skating

References

American College of Sports Medicine (2013). Guidelines for Exercise Testing and Prescription, William & Wilkins, 9, 401

Bélanger M, Boulay P (2005). Effect of an aerobic exercise training program on resting metabolic rate in chronically beta-adrenergic blocked hypertensive patients. J Cardiopulm Rehabil. 25(6):354-60.

Dreeben-Irimia O (2008). Physical Therapy Clinical Handbook for PTAs. Jones and Bartlett Publishers, 373.

Gladson B (2011). Pharmacology for Rehabilitation Professionals, Elsevier Saunders (2) 486-490.

Hung RK, Al-Mallah MH, Whelton SP, Michos ED, Blumenthal RS, Ehrman JK, Brawner CA, Keteyian SJ, Blaha MJ (2016). Effect of Beta-Blocker Therapy, Maximal Heart Rate, and Exercise Capacity During Stress Testing on Long-Term Survival (from The Henry Ford Exercise Testing Project). Am J Cardiol. 2016 Dec 1;118(11):1751-1757.

Tesch PA (1985). Exercise performance and beta-blockade. Sports Med. 1985 Nov-Dec;2(6):389-412.

Niedfeldt MW (2002). Managing Hypertension in Athletes and Physically Active Patients. Am Fam Physician. 1;66(3):445-453.

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