Hypertension and Heart Failure Flashcards
ACE inhibitors mechanism
Competitive inhibitors of ACE
Reduce angiotensin II formation
Cause arteriolar dilation and some venodilation
Reduce aldosterone so promote diuresis
Hypertension first line therapy
ACE inhibitors or angiotensin receptor blockers
Calcium channel blockers
Diuretics
ACE inhibitors uses
HF, left ventricular dysfunction
ACE inhibitors ADRs
Dry cough due to increased bradykinin
Angio oedema
Renal failure
Hyperkalaemia
ACE inhibitor contraindications
Care - renal impairment, peripheral vascular disease
Not in pregnancy, renovascular hypertension
Lisinopril
ACE inhibitor
Ramipril
ACE inhibitor
Angiotensin receptor blockers mechanism
Bind to AT1 receptor
Inhibit vasoconstriction and aldosterone stimulation
Angiotensin receptor blockers ADRs
Renal failure
Angiotensin receptor blockers contraindications
Care - renal impairment, peripheral vascular disease
Not in pregnancy, renovascular hypertension
Losartan
Angiotensin receptor blocker
Valsartan
Angiotensin receptor blocker
Calcium channel blocker mechanism
Bind to specific alpha subunits of L type calcium channel
Reduces calcium entry
Vasodilation of peripheral, coronary and pulmonary arteries
Little effect on veins
Calcium channel blocker uses
Angina
Dihydropyridines
Class of calcium channel blocker
Dihydropyridines pharmacokinetics
Good oral absorption
>90% protein bound
Metabolised by liver
Few have active metabolites
Dihydropyridines ADRs
Oedema
SNS activation via baroreceptor reflex - tachycardia, palpitations
Flushing, sweating, headache
Gingival hyperplasia (rare)
Rifedipine
Dihydropyridine CCB
Amlodipine
Dihydropyridine CCB
Phenylalkylamines
Class of CCB
impede calcium transport across myocardial and vascular smooth muscle cell membranes
Peripheral vasodilation
Decreased preload
Decreased contractility
Class 4 anti arrhythmics- prolong refactory period
Verapamil depresses SAN and blocks AVN conductance
Phenylalkylamines ADRs
Bradycardia
Constipation
Negative inotrope, worsens heart failure
Verapamil
Phenylalkylamines
CCB
Also class 4 antiarrhythmic
Benzothiazepines
CCBs Impede calcium transport across myocardial and vascular smooth muscle membranes Prolong AP and refactory period Peripheral vasodilation Reduced preload Reduced contractility
Benzothiazepines ADRs
Negative inotrope, but less than verapamil
Bradycardia
CCB contraindications
Care with beta blockers
Not in heart block or heart failure
Diltiazem
Benzothiazepines
CCB
Alpha blocker mechanism
Selective antagonism at post synaptic alpha 1 receptors
Antagonise NA
TPR reduced
More effective in upright position
Benign effects on plasma lipid and glucose
Uses of alpha blockers
Safe in renal disease
BPH
Contraindications for alpha blockers
Care in postural hypotension, heart failure
Not in urinary incontinence
Doxazosin
Alpha blocker
Beta blockers mechanism
Reduce HR and CO
Developed for angina but found to lower blood pressure
Inhibit renin release
TPR initially increases, later falls to normal
Beta blocker ADRs
Bradycardia Lethargy Impaired concentration Reduced exercise tolerance Cold hands
Beta blocker contraindications
Care in HF, PVD, diabetes
Not in asthma, COPD, heart block
Not in pregnancy (low blood flow causes intrauterine growth retardation)
Alskiren mechanism
Direct renin inhibitor, blocks angiotensinogen conversion to AT1
Reduces plasma renin activity 50-80%
Alskiren pharmacokinetics
Bioavailability 2.6% T1/2~40 hrs Steady state takes 5-8 days Less than 1% renal excretion 78% unchanged in faeces Not cyp450
Alskiren contraindications
Care in HF, hyperkalaemia, Na/h2o deplete, renal impairment/ stenosis
Not in pregnancy
Alskiren DDIs
Frusemide
Centrally acting agents for hypertension
Methyldopa-alpha 2 receptor agonist
Moxonidine - imidazoline receptor agonist - alpha 2 effect
Cause tiredness, lethargy, depression
Dobutamine
Beta receptor agonist
Positive inotrope
Used in cardiogenic shock or acute reversible heart failure to increase CO
Treatment for hypertensive emergency
IV sodium nitroprusside (acts like NO)
If stopping beta blockers
Come off slowly- triggers arrhythmia.
Candesartan
ARB
Target BPs
Systolic 130 in kidney disease
140 in diabetes
150 in normal