Cardiology Drugs Flashcards
Give examples of the functional responses of alpha-1 adrenoceptors.
Vasoconstriction
Increased blood pressure
Contraction of visceral smooth muscle
Relaxation of GI tract
What is adrenaline used for in clinical practice?
Adjunct in cardiopulmonary resuscitation
In anaphylaxis
To extend effects of local anaesthesia
All effects are due to vasoconstriction and increasing blood pressure, promotes blood flow to coronary and cerebral arteries
Give examples of alpha-1 adrenoceptor agonists.
Phenylephrine, methoxamine, adrenaline, noradrenaline
Give examples of alpha-2 adrenoceptor agonists.
Clonidine, methoxamine, adrenaline, noradrenaline
Give examples of alpha-1 adrenoceptor antagonists.
Prazosin, phentolamine, phenoxybenzamine
Give examples of alpha-2 adrenoceptor antagonists.
Yohimibine, phentolamine, phenoxybenzamine
Give examples of clinical uses of adrenoceptor agonists.
Reduction of intra-ocular pressure in chronic simple glaucoma
Prolong effects of local anaesthetics
Reduce systemic toxicity
Offset hypotension in spinal/epidural anaesthesia
Give examples of clinical uses of adrenoceptor antagonists.
Treatment of adrenal medulla tumours
Dilation of arterioles and veins
What is tamsulosin and what is its clinical use?
An alpha-1 antagonist used in benign prostatic hyperplasia, relaxing the prostate to prevent the urethra from being blocked
Give examples of beta-1 adrenoceptor agonists.
Dobutamine, isoprenaline, adrenaline, noradrenaline
Give examples of beta-2 adrenoceptor agonists.
Salbutamol, isoprenaline, adrenaline
Give examples of beta-1 adrenoceptor antagonists.
Atenolol, propranolol
Give examples of beta-2 adrenoceptor antagonists.
Butoxamine, propranolol
Why is propranolol contraindicated in asthma?
Because it is a non-selective beta-receptor antagonist so may cause bronchospasm which could be fatal in an asthma sufferer.
What are the side effects of beta-2 agonists when taken orally?
Tremors
Tachycardia
Hypokalaemia
What is the most common indication for a beta-2 agonist?
Asthma relief
Give two examples of indications for salbutamol.
Asthma
Suppression of premature labour
What are the common indications for non selective or beta-1 selective adrenceptor antagonists?
Hypertension
Reduction of aqueous humour in chronic simple glaucoma (timolol)
Controlling symptoms of thyrotoxicosis
Migraine prophylaxis
How do beta-receptor antagonists treat hypertension?
Reduce cardiac output
Reduce release of renin due to reduced kidney perfusion
Reduce sympathetic tone
How are beta antagonists useful in angina prophylaxis?
Reduce cardiac rate and force, thus prolonging diastole and increasing oxygen supply to coronary arteries
Give examples of muscarinic AChR agonists.
Pilocarpine, muscarine
Give examples of muscarinic AChR antagonists.
Hyoscine, atropine
Give examples of nicotinic AChR agonists.
Nicotine, suxamethonium
Give examples of nicotinic AChR antagonists.
Atracurium, tubocurarine
Clinical uses for drugs acting at muscarinic AChR.
Antiemetics, anti asthma, eye exams (pupil dilation), glaucoma
Clinical uses for drugs acting at nicotinic AChR.
Paralysing agents, nicotine addiction, Alzheimer’s, Parkinson’s
What effects do non-depolarising nAChR antagonists have? Give examples.
Cause flaccid paralysis, reversed by AChE inhibitors however, effects are limited when ACh concentrations increase.
Atracurium
Pancuronium used in euthanasia
What effects do depolarising nAChR antagonists have? Give examples.
Sustained depolarisation, leading to decreased electrical sensitivity, fasciculation and flaccid paralysis. Not reversible with AChE inhibitors.
Suxamethonium
Decamethonium
What is Champix?
Varenicline
Partial agonist at CNS nAChRs used in nicotine addiction. Although expensive, long term cheaper than NRT.
What are muscarinic AChR agonists used for in practice? Give examples.
Pilocarpine used in glaucoma
Bathanechol used in bladder disorders
What are muscarinic AChR antagonists used for in practice? Give examples.
Clozapine- antipsychotic acting via dopamine receptors
Atropine used to prevent bronchial secretions during surgery
Tiotropium is a 2nd line asthma treatment
Hyoscine is used for motion sickness
Solifenacin acts on M3 receptors for bladder hyperactivity
How does botox work?
Blocks the release of ACh via breaking down of SNARE proteins
How do organic nitrates work to relieve angina?
Activation of soluble guanylyl cyclase to form cGMP, an allosteric regulator of proteins. Protein kinase G phosphorylates specific target proteins resulting in cytoplasmic calcium concentrations reducing, thus muscle relaxation and reduction in cardiac workload.
How do organic nitrates work to relieve angina?
Activation of soluble guanylyl cyclase to form cGMP, an allosteric regulator of proteins. Protein kinase G phosphorylates specific target proteins resulting in cytoplasmic calcium concentrations reducing, thus muscle relaxation.
What effect does the dilation induced by nitrates have on the cardiac system?
Reduction in central venous pressure, venous return and preload.
Describe the action of GTN tablets.
As a sublingual tablet, onset is rapid with duration of action lasting 20-30 minutes. Due to this, tolerance is unlikely.
Describe the action of isosorbide mononitrate tablets.
Orally active with a 4-5 hour half life. In the XL form, tolerance is possible so a nitrate free period is recommended.
What is the indication for Rociguat?
Chronic thromboembolic pulmonary hypertension, fibrous clots in the lungs leading to high blood pressure and right side heart failure.
Give examples of PDE 3 inhibitors and their action.
Enoximone- increase cAMP, increasing force/rate of contraction. For short term IV use in acute heart failure.
Cilostazol- relaxes smooth muscle and inhibits platelet aggregation.
Give examples of PDE 4 inhibitors and their action.
Roflumilast is used in severe COPD
Apremilast is used in active psoriatic arthritis that is unresponsive to anti rheumatics.
What is sildenafil?
A PDE 5 inhibitor marketed for erectile dysfunction and also as Revatio for pulmonary arterial hypertension.
What is tadalafil?
A PDE 5 inhibitor used in benign prostatic hyperplasia.
What is a common side effect of tadalafil?
Visual disturbances.
Describe the mechanism of action of ACE inhibitors.
Prevent the conversion of angiotensin I to angiotensin II, thus halting the renin-angiotensin system and leading to vasodilation.
What is the most common side effect of ACE inhibitors and why does this occur?
Dry cough. Due to the accumulation of bradykinin in the airways.
What effect does the dilation induced by ACE inhibitors have on the cardiac system?
Reduction in cardiac workload without affecting contractility, thus increasing cardiac output.
Why do the kidneys maintain perfusion upon administration of ACE inhibitors?
ACE inhibitors are more effective on angiotensin sensitive vascular beds, unlike the kidneys.
What side effects occur with ACE inhibitors?
Dry cough
Rash
Angioedema
Give two examples of contraindications of ACE inhibitors and why.
Pregnancy- risk of congenital abnormalities of foetus in 2nd/3rd trimester.
Renal artery stenosis- risk of progressive renal failure.
Describe the mechanism of action of angiotensin I receptor blockers.
Prevent the conversion of angiotensin I to angiotensin II via competitive inhibition of angiotensin binding. Thus reducing vasoconstriction and salt/water retention.
What long term benefits are associated with angiotensin I receptor blockers?
Improved endothelial function
Destiffening and remodelling of large arteries
Name the three types of calcium channel blockers.
Dihydropyridines
Benzothiazepines
Phenylalkylamines
Describe the mechanism of action of calcium channel blockers.
Reduce the opening of L-type calcium channels, thus preventing influx of calcium to cause vasoconstriction.
What effect does the dilation induced by calcium channel blockers have on the cardiac system?
Reducing AV node conduction, myocardial contractility, heart rate and arterial tone due to vasodilation.
What are the effects of chronic administration of CCBs on the cardiac system?
Reduced mean arterial pressure. Increase in vascular resistance and coronary blood flow
What are the effects of acute administration of CCBs on the cardiac system?
Increased cardiac output
Increased heart rate with dihydropyridines
What makes dihydropyridine CCBs vascular selective?
Favour the inactive state of L-type calcium channels, resting potential of vascular smooth muscle cells compared to cardiac myocytes is depolarised.
What causes cardiac selectivity of benzothiazepine
phenylalkylamine CCBs?
Use dependence- enhance blockade of L-type calcium channels with repeated depolarisation.
Give examples of side effects caused by CCBs.
Headache Constipation Oedema Hypotension AV node block Cardiodepression
Why are beta-blockers less commonly used in hypertension?
Less effective at stroke prevention and more likely to cause diabetes.
In what cases are beta-blockers given in hypertension?
Young people unable to tolerate ACEi, women of child bearing potential and those with higher sympathetic drive.
Give examples of side effects caused by beta-blockers.
Bronchoconstriction
Precipitation of cardiac failure
Raynaud’s
Hypoglycaemia