Pharmacology - beta blockers Flashcards
(21 cards)
What do BB do?
Block adrenergic receptors throughout the body
(blocking the action of hormones like adrenaline)
- block part of the the SNS
What are they used to treat?
angina heart failure hypertension heart attack atrial fibrillation anxiety tremor
What organ are they trying to work on?
the heart
-trying to slow it down
What type of form of medication do BB come in?
Tablets
What effect do BB have on HT and normotensive subjects when exercising?
Detrimental effects due to: decreasing force and rate of heart decreasing BP decreasing vasodilation in SM decreasing airway diameter decrease muscle TG's as an energy source
What sports may find BB useful?
aiming sporting
archery, javelin, shooting, darts
What happens when the beta 1 receptor (in the heart) is activated?
increased cardiac function and rate which increases BP
What happens when the beta 1 receptor is blocked?
inhibit the action of epinephrine and norepinephrine
reduce cardiac function and BP
What are non selective BB?
Causes blockage of beta 1 and beta 2 receptors (bronchioles of the lungs and the arteries of the skeletal muscles)
Give an example of a non selective BB?
propranolol
penbutolol
carteolol
What are the implications of using a non selective BB in an asthmatic patient?
May not be able to dilate their airways when using their inhaler because all beta receptors are blocked may cause breathing problems or asphyxation (oxygen deprivation/death)
Give an example of an appropriate BB for asthmatic patients with CV problems
Atenolol (treats high BP and cardiac arrthymias) - mainly has beta 1 receptor blocking activity - little effect on respiratory blocking (beta 2 receptors)
How does exercise affect BB action?
Exercise and BB have opposing effects
- exercise doesn’t override the reduction of HR due to the drugs
may seriously alter serum lipid levels depending on type of BB
How does BB effect cardiac output?
BB target HR and SV therefore CO is much lower
- decreased resting and exercising HR - effect exercise capacity
During exercise what methods should be employed to calculate intensity?
RPE
What happens to RHR, ex HR, CO and VO2 max with the use of BB?
RHR - decreases by all types of BB
exercising HR - decreased by all types
CO - conflicting data - exercise either reduces CO or doesn’t change it
VO2 max - reduced acutely by all types, can increase with training with chronic use
What are the metabolic consequences of BB?
- lipolysis, muscle TGs utilisation, glycogenolysis, serum K+ levels
AT lipolysis is impaired
Muscle TG utilisation - impaired by non selective agents
Glycogenolysis - impaired by non selective
Serum K+ - post exercise levels are decreased with non selective agents
How do BB impact on exercise performance and training?
Cardioselective (atenolol) suppresses MHR less than noncardioselective agents
- all BB reduce VO2 max
Non selective - can suppress training effects acutely but chronic use -fitness improvements with exercise
Decreased time to exhaustion - tire more quickly
Cardioselective - interfere with substrate use less than non selective during exercise
Benefits of BB in sports (however known as abusing BB)
Slower HR in shooting = reduced DM tremor
Pistol shooting performance increases by 13.4% mainly from reduced hand tremor not HR
No effects on visual, auditory, reaction time, strength, power or muscle endurance
What is propanolol’s effect on sweating?
Can increase sweat loss which means fluid replacements necessary but need to be careful in HT patients who need to avoid excess salt as sodium will need to be replaced
Basic guidance and tips for BB use
Adjust exercise targets as RHR and exercising HR are affected
No appearance of thermoregulatory effect but propanolol can increase sweat loss so fluid replacement with Na+ is unwise in HT patients who have to avoid salt
It is banned in competition unless verified
Cardioselective (atenolol) are better than non selective (propanolol)
Monitor dose and effect as fitness improves
Careful combining BB and exercise - ex has multiple benefits
