Cardiovascular Drugs Flashcards
Loop diuretics name
Furosemide, bumetanide
Loop diuretics indications
- Relief of breathlessness in acute pulmonary oedema in conjunction with oxygen and nitrates
- Symptomatic treatment of fluid overload in chronic heart failure
- Symptomatic treatment of fluid overload in other oedematous states: renal / hepatic disease - given in combination with other diuretics
Loop diuretics MOA
- Act on ascending limb of Henlé
- Inhibit Na+/K+/2Cl- co-transporter.
- This normally transports sodium potassium and chloride ions from tubular lumen into epithelial cell, allowing water to follow by osmosis
- Inhibiting this process leaves water in the lumen
- Water then excreted in urine
- Also cause dilation of capacitance veins - in HF this reduces preload and improves contractile function of overstretched cardiac muscle
Loop diuretics administration
IV: for acute pulmonary oedema - administered slowly
Oral: BD
Loop diuretics contraindications
- Severe dehydration or hypovolemia
- Caution in hepatic encephalopathy, hypokalaemia and hyponatraemia
- Gout: inhibit uric acid excretion so can worsen
Loop diuretics side effects
- Diuresis can lead to dehydration and hypotension
- Inhibiting Na+/K+/Cl- transporter increases urinary losses of sodium / potassium / chloride.
- This also increases excretion of magnesium, calcium and hydrogen, so overall can cause low electrolyte state and metabolic alkalosis
- Hearing loss / tinnitus: same co-transporter found in inner ear
Loop diuretics interactions
- Increase concentration of drugs metabolised by kidney especially lithium
- Digoxin: increased toxicity due to diuretic associated hypokalaemia
- Aminoglycosides: increase ototoxicity and nephrotoxicity
Loop diuretics patient info:
Avoid taking oral doses at night due to increased urinary output
Thiazide diuretics examples
Bendroflumethiazide, indapamide, chlorthalidone
Thiazide diuretics indications
- Hypertension: alternative where CCB would otherwise be used, but is unsuitable due to oedema or heart failure
- Hypertension additional treatment where BP is not controlled by CCB + ACEi / ARB
Thiazide diuretics MOA
- Inhibit the Na+/Cl- co-transporter in the distal convoluted tubule
- Prevents reabsorption of sodium and associated water
- Resulting diuresis causes initial fall in extracellular fluid volume
- Long-term, compensatory mechanisms such as RAAS tend to reverse this
- Longer term mechanism may be due to vasodilation
Thiazide diuretics administration
Oral
Thiazide diuretics contraindications
- CI in hypokalaemia
- Avoid in hyponatraemia
- Reduce uric acid excretion so caution in gout
Thiazide diuretics side effects
- Prevention of sodium ion reabsorption can cause hyponatraemia
- Increased delivery of sodium to distal tubule, where it can be exchanged for potassium, leads to hypokalaemia - cardiac arrhythmias
- May increase plasma glucose, LDL and triglycerides
- Impotence in men
Thiazide diuretics interactions
- NSAIDs: may reduce effectiveness - low dose aspirin fine
- Other drugs that lower serum potassium concentration best avoided
Potassium-sparing diuretics name
Amiloride (co-amilofruse, amilozide)
Potassium-sparing diuretics indication
- Part of combination therapy for treatment of hypokalaemia during other diuretic treatment
- Aldosterone antagonists e.g. spironolactone can be used as alternative
Potassium-sparing diuretics MOA
- Weak diuretics alone but in combination can enhance diuresis while preventing hypokalaemia
- Acts on distal convoluted tubule
- Inhibits reabsorption of sodium (and therefore water) by epithelial sodium channels
- Causes excretion of sodium and water and retention of potassium
Co-amilofruse: amiloride + furosemide
Co-amilozide: amiloride + hydrochlorothiazide
Potassium-sparing diuretics contraindications
- Severe renal impairment and hyperkalaemia
- Do not start in context of hypokalaemia as effect can be unpredictable
- Avoid in states of volume depletion
Potassium-sparing diuretics side effects
- Uncommon at low doses
- GI upset may occur
- In combination with other diuretics may cause dizziness, hypotension and urinary symptoms
- Low electrolyte disturbance
Potassium-sparing diuretics interactions
- Do not use in combination with other K+ sparing drugs due to risk of hyperkalaemia e.g. potassium supplements and aldosterone antagonists
- Digoxin and lithium: alters renal clearance - adjust dose
Beta-blockers examples
Bisoprolol, propranolol, metoprolol, atenolol
Beta-blockers indications
- Ischaemic heart disease: first-line, to improve symptoms and prognosis associated with angina and ACS
- Chronic heart failure: first-line to improve prognosis
- AF: first line to reduce ventricular and maintain sinus rhythm in paroxysmal
- Supraventricular tachycardia: first-line option in patients without circulatory compromise to restore sinus rhythm
- Hypertension: when CCB / ACEi / thiazides are insufficient
Beta-blockers MOA
- Block beta-1 receptor located in heart
- Reduces force of contraction and speed of conduction
- This reduces cardiac work + o2 demand and increases myocardial perfusion
- Protect heart from effects of chronic sympathetic stimulation
- Slow ventricular rate in AF by prolonged refractory period of AV node
- Break self-perpetuating circuit of SVT and restore sinus rhythm
- Hypertension: reduce renin secretion from kidney as this is mediated by beta-1
Beta-blockers administration
- Oral, take at equal intervals throughout day
- IV preparations when rapid effect necessary
Beta-blockers contra-indications
- Asthma: can cause life-threatening bronchospasm due to beta-2 antagonism in airway smooth muscle
- COPD: usually safe but should chose cardioselective (not propranolol)
- Heart failure: start at low dose as may initially impair cardiac function
- Haemodynamic instability: avoid
- Heart block: contra-indication
- Hepatic failure: dose reduction
Beta-blockers side effects
- fatigue
- cold extremities
- headache
- GI disturbance
- sleep disturbance and nightmares
- impotence in men
Beta-blockers interactions
- DO NOT PRESCRIBE with non-dihydropine CCB - verapamil, diltiazem. Can cause heart failure, bradycardia and asystole/
Calcium channel blockers examples
Dihydropine: Amlodipine, nifedipine - vascular selective
Non-dihydrpine: diltiazem, verapamil - cardioselective
Calcium channel blockers indications
- Hypertension: Dihydropines 1st line in >55 or Afro-Caribbean
- Dihydropines reduce risk of stroke, MI or death from CVD
- All used to control symptoms of stable angina - beta-blockers main alternative
- Non-dihydropines control cardiac rate in those with SV arrhythmias (SVT, atrial flutter, AF)
Calcium channel blockers MOA
- Decrease calcium entry in vascular and cardiac cells
- Causes relaxation and vasodilation in arterial smooth muscle, lowering arterial pressure
- Reduce myocardial contractility
- Suppress cardiac conduction, particularly across AV node, slowing ventricular contraction
- Reduced cardiac rate + contractility + afterload = reduced myocardial oxygen demand - prevents angina
Calcium channel blockers administration
Oral
Verapamil available IV for acute arrhythmias
Calcium channel blockers contra-indactions
- Poor LV function: non-dihydropines can precipitate HF
- AV nodal conduction delay: can provoke complete heart block
- Dihydropines contraindicated in patients with unstable angina: vasodilation causes increase in contractility and tachycardia, increasing myocardial oxygen demand
- Dihydropines contra-indicated in patients with severe aortic stenosis - can provoke collapse
Calcium channel blockers side effects
- Dihydropines: ankle swelling, flushing, headache and palpitations due to vasodilation and compensatory tachycardia.
- Verapamil: constipation, less often bradycardia, heart block and cardiac failure
Calcium channel blockers interactions
- DO NOT PRESCRIBE with non-dihydropine CCB - verapamil, diltiazem. Can cause heart failure, bradycardia and asystole as both negative chronotropes and inotropes
ACE Inhibitors examples
Ramipril, Lisinopril, Perindopril
ACE Inhibitors indications
- Hypertension: 1st / 2nd line treatment to reduce risk of cardiovascular events
- Chronic heart failure: 1st line treatment of all grades to improve symptoms and prognosis
- Ischaemic heart disease: reduce risk of subsequent cardio/cerebrovascular events
- Diabetic nephropathy and CKD with proteinuria: reduces proteinuria and progression
ACE Inhibitors MOA
- Block ACE, preventing conversion of angiotensin I to angiotensin II
- Angiotensin II causes vasoconstriction and stimulates aldosterone secretion
- Blocking reduces afterload (PVR) which lowers blood pressure
- Dilates efferent glomerular arteriole which reduces intraglomerular pressure and slows CKD progression
- Reducing aldosterone promotes sodium and water excretion - this helps reduce preload which is beneficial in heart failure
ACE Inhibitors contra-indication
- Renal artery stenosis
- AKI
- Pregnancy / breast-feeding
- CKD: use lower doses and monitor effect on renal function closely
ACE Inhibitors side effects
- Hypotension
- Chronic dry cough due to increased bradykinin
- Hyperkalaemia due to reduced aldosterone
- Cause or worsen renal failure (dilation of arteriole needed to maintain renal perfusion)
- Idiosyncratic angioedema, anaphylaxis
ACE Inhibitors interactions
-Avoid other drugs that increase potassium e.g. supplements, K+-sparing diuretics
Angiotensin receptor blockers examples
Losartan, Candesartan, Irbesartan
Angiotensin receptor blockers indications
Used 2nd line when ACEi not tolerated due to dry cough. Indications are the same:
- Hypertension: 1st / 2nd line treatment to reduce risk of cardiovascular events
- Chronic heart failure: 1st line treatment of all grades to improve symptoms and prognosis
- Ischaemic heart disease: reduce risk of subsequent cardio/cerebrovascular events
- Diabetic nephropathy and CKD with proteinuria: reduces proteinuria and progression
Angiotensin receptor blockers MOA
- Block action of angiotensin II on AT1 receptor
- Angiotensin II causes vasoconstriction and stimulates aldosterone secretion
- Blocking reduces afterload (PVR) which lowers blood pressure
- Dilates efferent glomerular arteriole which reduces intraglomerular pressure and slows CKD progression
- Reducing aldosterone promotes sodium and water excretion - this helps reduce preload which is beneficial in heart failure
Angiotensin receptor blockers contra-indications
- Renal artery stenosis
- AKI
- Pregnancy / breast-feeding
- CKD: use lower doses and monitor effect on renal function closely
Angiotensin receptor blockers side effects
- Hypotension
- Hyperkalaemia
- Cause or worsen renal failure
Angiotensin receptor blockers interactions
- Potassium raising drugs
- Diuretics: profound 1st dose hypotension
- NSAIDs: increased risk renal failure