Hypertensive drugs (Lecture 6) Flashcards
What are the indications for an alpha 1 blocker, what is the example of the drug and some side effects (why you wouldn’t use it).
Doxazocin
Indications: Used in mild to moderative HTN. Works as a mild vasodilator (increase venous capacitance) and decrease arteriolar resistance.
Side effects: postural hypotension, drowsiness, inhibition of ejaculation etc.
What is the example of the alpha 2 agonist, what does it do, what are some side effects?
Clonidine
Reduces the central preganglionic noradrenaline release. Decreases sympathetic output to the heart. With time they enter the brain and work on the alpha receptors in the brain to decrease blood pressure. It will initially cause an increase in BP due to the effect on the vascular smooth muscle.
Causes decrease in stroke volume in supine patients. Will negate the ANS when someone stands up and may cause postural hypotension.
What are the beta-blockers that we need to know and what are the different generations and what receptors do they act on?
Propranolol, metoprolol and carvedilol.
Chronotrope vs ionotrope vs dromotrope?
Chronotrope: Increase heart rate.
Ionotrope: Increase force of contraction.
Dromotrope: Increase rate of conduction.
What are the 3 ways that beta-blockers decrease hypertension?
The antihypertensive effect is mainly via an adrenergic block:
- Reduction in cardiac output (initially)
- Reduction in beta 1 stimulated renin release from juxtaglomerular cells.
- Chronic use will decrease vascular resistance (however the initial drop in CO will cause a compensatory increase in vascular resistance).
What ‘trope’ (for example ionotrope) does a beta blocker produce and why is it useful?
Rate control: Negative chronotrope.
Decreases work of heart: Negative ionotrope.
Decreases conduction through the AV node: Negative dromotrope.
What are the 3 main uses of beta blockers and why?
- Antiarrythmic: Controls the conduction and excitibility of the heart.
- Angina and MI: Negative ionotrope and chronotrope so decreases the load on the heart.
- Heart failure: use Carvidilol
Not indicated for hypertension.
What are the main consequences of beta blockers?
- Bronchospasm/asthma due to beta 2 interaction (could use metoprolol).
- Reduced exercise tolerance.
- Cold peripheries because of vasoconstriction.
- Worsening of heart block
- CNS effects (nightmares).
- Worsening lipid profile
What does beta blockers do to lipid profile and why?
Makes the lipid profile worse because it inhibits beta 2 stimulation of lipoprotein lipase (increase VLDL, LDL and decrease HDL).
It also may blunt catecholamine induced hepatic glyconeogenesis in response to hypoglycemia.
Which beta blockers are hydrophobic/hydrophilic and what are the benefits/disadvantages?
Metopralol and carvidalol have low bioavalability.
Why would you often not take someone off their beta-blocker quickly?
