Pharmacology - Antihypertensives Flashcards
When would CCBs be prescribed?
And what are the 3 classes?
Those over 55 years old
Patients of african-american/carribean origin at any age
Severe hypertension in pregnancy (nifedipine)
1-4-Dihydropyridines –> Nifedipine/Amlodipine (vascular)
Benzothiazepines –> Diltiazem (Intermediate)
Phenylalkylamines –> Verapamil (Cardiac)
What’s the mechanism of K+ channel activators
Activation of ATP-sensitive K+ channels in vascular smooth muscle
This causes membrane hyperpolarisation, and so the closure of L-type VACCs
Resulting in relaxation
What is Minoxidil
A K+ channel activator thats used in servere resistant hypertension
Should be used with a B-blocker and diuretic to prevent reflex tachycardia and fluid retension
What is Hydralazine?
Directly dialates arteries/arterioles
Used in severe hypertension in pregnancy with a diuretic and B-blocker
Also in heart faliure in people with afro-caribbean origin (with nitrates)
How do B-blockers work?
And list some different ones?
By antagonising B1 receptors in the heart
Atenolol (B1 selective)
Propanalol (non-selective)
Nebivolol (B1 selective, and stimulates NO secretion)
Pindolol (B1 selective, and partial agonist at low symp levels)
Labetalol/Carvedilol (non-selective, with some (a)1 antagonism)
What is the main purpose of central-acting drugs?
Eg, clonidine/(a)-methyldopa
Decrease sympathetic outflow….which will decrease BP
How does Trimetaphan work?
A competitive nicotinic acetylcholine receptor antagonist at the autonomic ganglion
Blocks ganglions, but clincially obsolete
They are adrenergic neurone blocking drugs
How do Guanethidine and Reserpine work?
Guanethidine –> Taken up by NET and VMAT, depeleting the vesicles of NA
Reserpine –> Taken up by NET and irreversible inhibits VMAT, preventing the uptake of NA into the vesicle and synapse
Name 2 (a)1-adrenoceptor antagonists
And what are the key adverse effects?
Doxazosin and Prazosin
First-dose hypotension
Dizziness
Fatigue
