PBL 49 Flashcards
Explain the MoA of ACE inhibitors
Block ACE in the lungs, this prevents Ang I to Ang II conversion.
Fall in BP from EFFERENT arteriole CONSTRICTION due to increased GFR, this leads to >filtration fraction and therefore increased urine OUTPUT
Side effects of ACE inhibitors
- Dry cough
- Rash
- Angio-oedema
- Hyperkalaemia
- Dizziness (from hypotension)
- Fatigue
MoA of warfarin
Vitamin K reductase inhibitor which is used to make clotting factors, so it is an anti-coagulant
Which clotting factors are affected by vitamin K reductase inhibition?
- Prothrombin
- VIIa (7a)
- IX (9)
- Protein C
- Protein S
Side effects of warfarin
- Severe bleeding incl. heavier than usual menstrual bleeding
- Red or brown urine
- Black or bloody stool
- Severe headache or stomach pain
- Haemoptysis
- Joint pain
- Vomiting blood
MoA of heparin
ANTICOAGULANT
Binds to enzyme inhibitor antithrombin III (AT)
AT will then inactivate thrombin, factor Xa and other proteases to inhibit thrombosis
Side effects of heparin
- Bruising more easily
- Bleeding that takes longer to stop
- Irritation/pain/redness/sores at injection site
- Allergic reactions such as hives/chills/fever
- Increased liver enzymes on liver function test
Give examples of selective, non-selective and additional alpha-blocking beta blockers
Selective: Atenolol, bisoprolol, metoprolol
Non-selective: Propanolol, timolol
Alpha-blocking: Carvedilol, labetolol
MoA of beta blockers
- Inhibit sympathetic stimulation by blocking the effects of adrenaline on B1 and B2 receptors (depending on selectivity)
- Reduces HR, contractility and blood pressure to improve myocardial O2 supply/demand ratio
- Reduces excitability of cardiac tissue and prevalence of arrhythmias (adrenaline increases inward Na+ and Ca2+ current)
Side effects of beta blockers
- Worsen heart failure
- Fall in BP –> can affect kidneys so you start with a low dose bb
- Fall in HR
- General sluggishness
- Cold peripheries
- Wheeze (contraindicated in brittle asthmatics)
- Dizziness/lightheadedness
MoA of alpha blockers
Block peripheral alpha-1 receptors which mediate sympathetic vasoconstriction, so you get vasodilation and a reduction in BP
Examples of alpha blockers
Doxasozin
Prazosin
Tamsulosin
Phenoxybenzamine
Side effects of alpha blockers
Postural hypotension
Headaches
Nausea
Dizziness
Lethargy
Swollen legs/ankles
Sleep disturbances
Tremor
Mechanism of diuretics: thiazides
Act on the DCT where they inhibit the sodium-chloride symporter leading to increased Na & Cl EXCRETION and therefore >H2O excretion, lowering the BP
Side effects of thiazides
Feeling thirsty w/dry mouth
HYPERURICAEMIA
Nausea/vomiting
Stomach pain
Diarrhoea
Loss of appetite
Constipation
Severe joint pain
Feeling dizzy and faint
Mechanism of diuretics: Mineralocorticoid receptor (aldosterone) antagonist
- What is the function of the receptor in general?
The action of the mineralocorticoid receptor (DCT) is to promote renal sodium retention, potassium excretion and inducing hypertension upon excessive activation
- This is blocked by antagonists which will lead to Na+ EXCRETION and K+ RETENTION (K+ sparing)
Examples of mineralocorticoid receptor/aldosterone antagonists
Spironolactone
Amiloride
Eplerenone
Side effects of mineralocorticoid receptor/aldosterone antagonists
HYPERKALAEMIA
Gynaecomastia (but NOT with eplerenone)
Drowsiness
Dizziness
Light-headedness
Upset stomach –> diarrhoea/nausea/vomiting
Headache
Mechanism of diuretics: loop diuretics
Inhibit the Na/K/2Cl co-transporter in the thick ascending loop of Henle in the renal tubule
- This prevents the transport of sodium ions from the lumenal side into the basolateral side for reabsorption. This inhibition results in increased excretion of H2O along with Na, Cl, Mg, Ca, H+, and K+ ions
Example of a loop diuretic
Furosemide
Side effects of loop diuretics
Hypokalaemia
Hyponatraemia
Hyperuricaemia –> gout
Nausea/vomiting
Diarrhoea
Constipation
Stomach cramping
Vertigo
Dizziness
Headache
Blurred visions
Mechanism of diuretics: osmotic diuretics
- Elevate blood plasma osmolality, resulting in enhanced flow of water from tissues, including the brain and CSF, into interstitial fluid and plasma
- Promotes diuresis in kidneys by increasing the concentration of filtrates in the kidney and blocking reabsorption of water by kidney tubules
Example of an osmotic diuretic
Mannitol
Side effects of osmotic diuretics
Dehydration
Headache
Nausea
Vomiting
Diarrhoea
Dry mouth
Thirst
Blurred vision
Mechanism of diuretics: Carbonic anhydrase inhibitors
- Inhibits CA and therefore causing an accumulation of carbonic acid
- The mechanism of diuresis involves the proximal tubule of the kidney. CA is found here allowing the resorption of bicarbonate, sodium, and chloride. By inhibiting this enzyme, these ions are excreted, along with excess water, lowering BP, ICP and intraocular pressure.
Example of a carbonic anhydrase inhibitor
Acetazolamide
Side effects of carbonic anhydrase inhibitors
Blurred vision
Dry mouth
Drowsiness
Loss of appetite
Nausea/vomiting
Diarrhoea
Changes in taste
MoA of digoxin
- Inhibits the Na/K+ ATPase, allowing more Na+ to remain within the cell. This will work upon the NCX, allowing more Ca2+ to be released by SERCA and more available for troponin C, >inotropy
- Has parasympathomimetic effects on the AV node, so it activates vagal efferent nerves to the heart, slowing electrical conduction in the AV node, therefore, decreasing heart rate,
Side effects of digoxin
Confusion
Dizziness
Malaise
Loss of appetite
Nausea/vomiting
Diarrhoea
Blurred vision
Skin rashes
MoA of oral anticoagulants
Inhibit the formation of fibrin clots in the final common pathway of the coagulation cascade, decreased fibrin formation and reduced thrombin-stimulated platelet aggregation will prevent the formation of thrombin
What are oral anticoagulants used for?
Prevent blood clots
Prevent stroke and embolism in those with AF
Examples of oral anticoagulants
Rivaroxaban (FXa)
Dabigatran (FIIa)
Apixaban (FXa)
Edoxaban (FXa)
Betrixaban (FXa)
Mechanism of angiotensin receptor blockers
- AKA angiotensin II receptor antagonists
- Block angiotensin II action at the AT1R and AT2R
- Ang II has a powerful vasoconstricting effect, increasing blood pressure. - - It also has aldosterone-secreting effects which are selectively blocked by ARBs as they block the binding of angiotensin II to the AT1 receptor.
Examples of ARBs
Losartan
Candesartan
Valsartan
Irbesartan
Side effects of ARBs
Headache
Fainting
Dizziness
Fatigue
Respiratory symptoms
Vomiting
Diarrhoea
Back pain
Leg swelling