43)Adrenolytic drugs

Question 1

Adrenolytic drugs

Answer 1

Inhibit action of AD + known as blockers

Question 2

alpha - blockers

Answer 2

a1 antagonists

• Block binding of NA to smooth muscle receptors ⇢ Vasodilation + ⇣ BP
• Used for hypertension

a1-non-selective blockers

• Phentolamine + Phenoxybenzamine
• also block a2 on presynaptic nerve endings
• NA acts on a2 to inhibit its own release
• Blockage of these receptors = more NA release
• Na then stimulates b1 receptors on heart ⇢ tachycardia + cardiac arrhythmias

Question 3

a1 selective blockers

Answer 3

Blocks receptors on smooth muscle ⇢ ⇣ peripheral resistance + ⇣ BP

• Doxazosin, Terazosin + Alfuzosin

Side effects

• Orthostatic hypotension
• Headaches
• Nasal congestion

Question 4

beta blockers

Answer 4

Competitive inhibitors at b-adrenergic receptors + counter effects of catecholamines

• ⇣ in symptomatic effect - mainly CV system
• Treats hypertension, heart failure, cardiac arrhythmia
• Glaucoma + migraine treatment

Question 5

b1 + b2 non selective blockers

Answer 5

Propranolol, pindolol + nadolol

• Blocks receptors = ⇣ HR, delayed conduction + ⇣ contractility
• Useful for hypertension, angina + arrhythmia
• Propranolol can penetrate CNS due to its lipophilicity

b2 receptors predominant in lungs

• Blockage = bronchoconstriction
• Not recommended for patients w/asthma/COPD

Question 6

b1 selective blockers

Answer 6

Acebutolol, Bisoprolol + Metoprolol

• Block b1 receptors in heart ⇢ ⇣ HR, contractility + Av conduction

Side effects of b-blockers

• sedation
• bradycardia
• hypotension
• nausea
• propranolol can cause sleep disturbances
• In oral cavity ⇢ dry mouth + ⇣ salvation

Question 7

DDIs

Answer 7

• Lidocaine should not be used w/patients on b-blockers as it is anti-arrhythmic
• Repeated administration of b-blockers + Verapamil = ⇡ risk of heart failure
• Cimetidine ⇣ hepatic 1st pass metabolism of propranolol, bisoprolol + metoprolol