CCBs and alpha beta blockers

Question 1

Classes of calcium channels

Answer 1

• high voltage activated dihydropyridine insensitive channels
• high voltage activated dihydropyridine sensitive channels
• low voltage activated channels

Question 2

Classes/structural forms of CCBs

Answer 2

• dihydropyridine: amlodipine and nifedipine (vascular)
• benzothiazepine: diltiazem (cardiac)
• phenylalkylamine: verapamil (cardiac)

Question 3

sides effect of CCBs

Answer 3

• both: hypotension
• cardiac selective: heart failure
• vascular selective: reflex tachycardia, peripheral oedema (more effective on artery than vein), natriuresis

Question 4

CCBs as antihypertensives

Answer 4

• some have short half life like nifedipine, need to use the sustained release formulation or long half life ones to reduce bp oscillation and adverse effects
• variable effect: use useful on isolated systolic hypertension and low renin status people
• actions in the non vascular smooth muscles like the lower eosophageal sphincter -> gastroesophageal reflux

Question 5

CCBs as antiarrthymics

Answer 5

• use cardiac only
• act on the supraventricular site and useful for delayed after depolarization
• do not use in ventricular tachycardia -> hypotension and cardiac arrest

Question 6

Locations of the alpha and beta receptors

Answer 6

• a1: smooth muscle
• a2: smooth muscles and presynaptic receptors
• b1: JG apparatus, presynaptic, heart
• b2: smooth muscles

Question 7

alpha blockers

Answer 7

• usually use alpha 1 selective blockers
• prazosin, doxazosin
• vascular smooth muscle in the arterioles and venules
• vasodilation -> antihypertensive

Question 8

alpha blockers side effects

Answer 8

• vasodilation related: hypotension, dizziness, light headedness (reduced venous return due to venous vasodilation), palpitations
• first dose phenomenon: orthostatic hypotension, especially when use with diuretics

Question 9

alpha blockers limitations

Answer 9

• when use alone -> neurohormonal activation: reflex tachycardia and increase sodium and water reabsorption
• use with diuretics or beta blockers can improve

Question 10

Beta blockers

Answer 10

• reduce CO (both force and rate)
• peripheral presynaptic receptors: reduce NE release and sympathetic mediated vasoconstriction
• reduce renin secretion and thus the sodium and water retention
• useful for MI, heart failure, arrhythmia, hypertension, angina
  e. g. metoprolol, propranolol, pindolol

Question 11

beta blockers side effects

Answer 11

• liver: hypoglycemia
• airway: bronchospasm- don’t use in asthma and obstructive diseases
• vasoconstriction: don’t use in severe peripheral vascular disease people and vasospatic disorder
• improve if use beta 1 selective ones

other

• CNS disturbances (less with low lipid solubility)
• heart failure and arrhythmia (less with pindolol)

Question 12

Classes of beta blockers

Answer 12

• first gen, non selective: propranolol
• second gen, beta 1 selective: metoprolol
• third gen, with vasodilator effect: (both a and b- labetalol, carvedilol), stimulate NO with b1 block- nebivolol
• partial agonist- pindolol