Anti hypertensives Flashcards
First line antihypertensives
- ACE-I
- AT1 blockers
- beta blockers
- Ca channel blockers
- Diuretics
ACE-I drugs
lisinopril, ‘-pril’
ACE-I MOA
- binds to angiotensin converter enzyme, prevent angI->angII, reduce angII, reduce water retention via RAAS
- prevent breakdown of bradykinin, which induces NO release & PG activation for vasodilation
ACE-I clinical uses
- hypertension
- heart failure
- following MI (reduce afterload & stress on heart)
- renal insufficiency
ACE-I adverse effects
- hypotension
- acute renal failure
- **angioedema & dry cough (bradykinin & substance P induced inflammation cause angioedema; bradykinin & PG reactions increase airway sensitivity
is ACE-I contraindicated in pregnancy
yes. potentially teratogenic
AT1 (angiotensin II type 1) blocker
valsartan, losartan ‘-sartan’
does AT1 blocker cause dry cough
no. bradykinin breakdown is not inhibited
AT1 blocker MOA
blocks receptor which angII binds to
is AT1 blocker contraindicated in pregnancy
yes
beta blockers drugs (selective, non selective)
non selective
- carvedilol
beta1
- bisoprolol, metoprolol XL
3rd gen
- nebivolol
MOA beta 1 blockers
- block B1 receptors, prevent activation of adenylyl cyclase -> ATP not converted to cAMP (cannot activate PKA) -> influx of Ca2+ through Ca channel does not occur -> no CICR
- no formation of actin-myosin complex, less contraction (heart beats slower)
MOA beta 2 blockers in airway constriction
- block beta receptors, prevent activation of adenylyl cyclase -> ATP not converted to cAMP -> cAMP cannot phosphorylate & inactivate MLCK in smooth muscles via B2 receptor binding -> MLCK in active form, induces contraction in airway
Behaviour of nebivolol (3rd gen beta blocker)
- B1 selective in low dose/ fast metabolizers
- non selective in high dose/ slow metabolizers
beta blocker clinical uses
- hypertension (decrease pumping strength)
- heart failure (decrease stress on heart)
- angina
- protect from post MI
beta blocker contraindicators
- non selective/ 3rd gen -> relatively contraindicated in asthma due to side effect of bronchoconstriction (salbutamol unable to relieve in event of asthma attack due to B2 blockage)
beta blocker adverse effects
- hypotension
- bradycardia
- AV nodal block
- clinical depression, vivid dreams (beta blocker blues)
Ca channel blockers
- nifedipine, amlodipine (DHP channel blockers)
Ca channel blockers MOA for hypertension
- decrease contraction of smooth muscle -> decrease vascular tone -> vasodilation and decrease BP
diuretics
thiazide
thiazide MOA
- block Na+/Cl- transporter at distal convoluted tubule -> reduce ion uptake -> reduce water uptake and retention-> more urine
- cause increase Ca2+ retention (in replacement of Na+) at distal convoluted tubule
thiazide clinical uses
- hypertension
- congestive HF (blood builds up in body due to HF; too much volume)
- nephrolithiasis (kidney stones) by removing Ca2+ from urine
- nephrogenic diabetes insipidus (inability to concentrate urine) by preventing reabsorption of ions
thiazide adverse effects
- hypokalaemic metabolic acidosis
- hyponatremia
- hyperuricaemia
- hyperglycaemia
- hyperlipidaemia
- hypercalcaemia
thiazide used carefully with what drugs (DDI)
NSAIDs
Second line hypertensives
- hydralazine (1st line HF)
- mineralocorticoid receptor agonist (HF)
- alpha adrenergic antagonists
alpha adrenergic antagonists examples
prazosin, alfuzosin, terazosin, ‘-zosin’
alpha adrenergic MOA
prevent a1-receptor mediated vascular smooth muscle constriction -> lower vessel tone -> decrease peripheral resistance
time taken to reach peak plasma concentration & half life of alpha adrenergic antagonist drugs
2.5 hrs, t1/2 = 7hrs
extensively bound to plasma proteins
metabolism of alpha adrenergic antagonists
metabolised by liver, excreted in faeces; can use in patients with renal failure
adverse effects of alpha adrenergic antagonists
- reflex tachycardia, palpitations
- orthostatic hypotension (low BP when sitting down)
- urinary frequency
alpha adrenergic antagonists clinical use
- 2nd line anti hypertensive
- urinary retention due to benign prostate hyperplasia
1st line for HTN: ranking order
A: ACE-I
B: beta blocker
C: Ca channel blocker
D: Diuretics - thiazide