Drugs Flashcards
Describe Thiazide diuretics: Example Mechanism of action Uses Side effects
Mild type of diuretic
E.g. Bendrofluamethazide
Promotes Na+ + water excretion from the kidneys by inhibiting reabsorption in the distal tubule by blocking the co-transporter
Used in hypertension and mild heart failure
Side effects - hypokalaemia (which can cause arrhythmias
Hypoglycaemia – Diabetes
↑ Uric Acid – Gout
Impotence
Describe Loop Diuretics Example Mechanism of action Uses Side effects
Stronger type of diuretic
E.g. Furosemide
Inhibits the Na+/K+/Cl- co-transporter, inhibiting the reabsorption of Na+ at the distal loop of Henle
Used in chronic heart failure and acute pulmonary oedema
Side effects - hypokalaemia, tiredness, arrhythmias
Hypoglycaemia – Diabetes
↑ Uric Acid – Gout
Impotence
Describe Cardioselective β Blockers Example Mechanism of action Uses Side effects Warnings
E.g. Atenolol
Only block β1 receptors –
Reduce Hr and Force, esp. during exercise or stress. Coronary vessel diameter is marginally reduced, but myocardial O₂ requirement falls – so better oxygenation of the myocardium
Used in Angina, Heart Failure, Hypertension
Side effects -
Cold Peripheries
Can cause Heart failure in the long term
Bradycardia
Fatigue – CO (β1) and skeletal
Never use in asthma – can result in bronchospasm mainly B2 blockers
Describe Non selective β Blockers Example Mechanism of action Uses Side effects Warnings
E.g. Propranolol
Competitive antagonists of adrenoceptors (G-coupled)
Block β1 - causes ↓ HR, force, and AV node conduction velocity
Block β2 receptors - causes bronchoconstriction and vasoconstriction
↓Maximal exercise tolerance by depressing rate, force, and CO during exercise
↓ coronary flow and myocardial O2 requirements, leading to better myocardium oxygenation
Side effects -
Cold Peripheries
Can cause Heart failure in the long term
Bradycardia
Fatigue – CO (β1) and skeletal muscle perfusion (β2) in exercise are regulated by adrenoceptors
Never use in asthma – can result in bronchospasm mainly B2 blockers
Describe Dihydropyridines (type of Ca channel blocker) Example Mechanism of action Uses Side effects
E.g. Amlodipine (-dipine) All Ca2+ antagonists ↓ entry of Ca2+ via voltage sensitive channels in SM cells, causing coronary and peripheral vasodiation and reducing heart oxygen consumption; all block L-type channels. Dihydropyridines are mainly peripheral vasodilators & can cause reflex tachycardia so often used with B blocker. Used in Hypertension & Angina Side effects - Ankle oedema Hypotension Dizziness
Describe Rate limiting calcium antagonists Example Mechanism of action Uses Side effects Warnings
E.g. Verapamil; Diltiazem
All Ca2+ antagonists ↓ entry of Ca2+ via voltage sensitive channels in SM cells, causing coronary and peripheral vasodilation and reducing heart oxygen consumption. all block L-type channels.
Rate limiting calcium antagonists also slow conduction at the SA & AV nodes.
Used in Supraventricular Arrhythmias (RLCA’s), hypertension and angina.
Side effects -
Ankle oedema
Hypotension
Dizziness
Avoid using with B blockers
Describe ACE inhibitors Example Mechanism of action Uses Side effects Warnings
E.g. Lisinopril
Blocks the conversion of angiotensin I – angiotensin II
Causes venous and arteriolar dilatation (↓ preload, afterload and TPR) to reduce arterial blood pressure and the cardiac load
Also ↓aldosterone release leading to ↓Na+ and H2O
Hypertension - ↓TPR and MABP
Cardiac failure - ↓vascular resistance, ↑ excretion of Na+ and H2O to regress LVH
Cardio protective for someone with previous MI
Side effects - Dry Cough, renal dysfunction, angioneurotic oedema
Hypotension – esp. when patient on diuretics
Don’t use in pregnancy
Good for kidneys in diabetic neuropathy but bad in renal artery stenosis
Describe angiotensin receptor blockers Example Mechanism of action Uses Side effects
E.g. Losartan
AT1 receptor antagonist – competitively blocks the agonist action of angiotensin II at AT1 receptors – Venous dilatation (↓ preload) and arteriolar dilatation (↓ afterload and ↓TPR), ↓ MABP
Also increases excretion of Na+ and H2O to regres LVH
Also used post MI
Side effects - hyperkalaemia, renal dysfunction
Good for kidneys in diabetic neuropathy but bad in renal artery stenosis
Describe nitrates - GTN & isosorbide mononitrate.
Mechanism - NO donor
Relax all types of smooth muscle, via their metabolism to nitric oxide.
↑ Coronary blood flow. In angina, there is no overall increase, but blood is directed towards the ischaemic zone – collateral arterioles dilated
» ↓myocardial O₂ req., ↓ afterload, ↑Ischaemic perfusion
GTN is short acting & isosorbide mononitrate is long acting
Isosorbide is used prophylactically for angina
Warnings - postural hypotension, headaches, need to build nitrate free period
Describe Potassium Channel Openers
Example
Mechanism
Uses
E.g. Nicorandil
↓ The Ca2+ sensitivity of smooth muscle
Used in stable angina and cases where nitrates are not working
Can cause mouth ulcers and gastric fistula
Describe Ivabradine
Mechanism
Uses
It is a novel medication which prolongs diastolic time by slectievly inhibiting the If current, reducing HR and increasing SV, preserving the BP
Selective for HCN channels
Used in chronic heart failure and stable angina
SE - problems with the eye perceiving light
If HR is still fast following B-blocker use them try Ivabradine.
Describe Antiplatelets Examples Mechanism Uses SE
E.g. Aspirin, Clopidogrel, Ticagrelor, Prasugrel
All prevent new thrombosis by preventing production of thromboxane A2, thereby inhibiting platelet aggregation.
Used in Angina, acute MI, and CVA/TIA
SE: Haemorrhage elsewhere, asthma (aspirin), peptic ulcer rupture.
Describe statins Examples Mechanism Uses SE Warnings
E.g. simvastatin, atorvastatin
Blocks HMG CoA reductase (competitive inhibitors) – Reduction of LDL production in Liver
Surface expression of the LDL receptors increases → increased clearance of LDL in the liver.
↓ inflammation, reversal of endothelial dysfunction, ↓ thrombosis, stabilisation of atherosclerotic plaques
(give at night time)
Used in hypercholesterolaemia, diabetes, angina, MI, CVA/TIA
SE: myopathy, renal failure
Describe Digoxin Mechanism Uses SE Warnings
Controls cardiac rhythm by having a block effect between the atria and ventricles –> inhibits the Na/K pump.
It also increases the contractility of the heart.
Used in heart failure coupled with AF.
Can cause bradycardia and heart block
Irritable to ventricles causing ventricular arrhythmias – can cause nausea, yellow vision, bradycardia and heart block so plasma digoxin levels are measured closely.
Describe Atropine
Mechanism
Atropine is a non-selective muscarinic receptor antagonist which increases HR to reverse bradycardia.
It is the first line treatment of bradycardia - if it does not initially work, increase the dose incrementally until the desired heart rate is achieved
