Pharmacology of hypertension Flashcards
What is the drug target for ACE inhibitors?
Angiotensin converting enzyme
List some example of ACE inhibitors
Ramipril, Lisinopril, Perindopril
Outline the primary mechanism of action of ACE inhibitors
Inhibit the angiotensin converting enzyme preventing the conversion of angiotensin1 to angiotensin2 by ACE
What are the main side effects associated with the use of ACE inhibitors?
Cough, hypotension, hyperkalaemia, foetal injury, renal failure, angioedema
Which ACE inhibitor is NOT a pro-drug?
Lisinopril
Most ACE inhibitors are pro-drugs, what is required for their activation?
Require hepatic activation to generate the active metabolites required for therapeutic effects
When prescribing ACE inhibitors what must be regularly monitored in the patient?
eGFR and serum potassium
List two examples of calcium channel blockers
Amlodipine and Felodipine
What are the drug targets for Calcium channel blockers?
L-type calcium channels
Outline the primary mechanism of action of Calcium channel blockers
Block L-type calcium channels on vascular smooth muscle, resulting in a decrease in calcium influx preventing muscle contraction. The resultant vasodilation reduces peripheral resistance
What are the main side effects associated with use of calcium channel blockers?
Ankle oedema, constipation, palpitations, flushing, headaches
What is the drug target for Thiazide or Thiazide diuretics?
Sodium/chloride cotransporter
Outline the primary mechanism of action of Thiazide or Thiazide-like diuretics
Block Na+/Cl- co-transporter in the early DCT therefore Na+ and Cl- reabsorption is inhibited. As a result the osmolarity of the tubular fluid increases, decreasing osmotic gradient for water reabsorption in the collecting duct
What are the main side effects associated with the use of Thiazide or Thiazide-like diuretics?
Hypokalaemia, hyponatraemia, metabolic alkalosis, hypercalcaemia, hyperglycaemia, hyperuricemia
How do Thiazide or thiazide-like diuretics cause hyperglycaemia?
Cause hyperpolarisation of pancreatic beta-cells
After how long do Thiazide or thiazide-like diuretics lose their diuretic affects?
Within 1-2 weeks of treatment.
List three examples of Angiotensin receptor blockers
Losartan, Irbesartan, Candesartan
Outline the primary mechanism of action of Angiotensin receptor blockers
Act as non-competitive anatomists at AT1 receptor found on kidneys and on the vasculature
What are the main side effects associated with the use of angiotensin receptor blockers
Hypotension, hyperkalaemia, foetal injury and renal failure
When are Angiotensin receptor blockers and ACE inhibitors likely to cause renal failure (what patients should we avoid prescribing them to) ?
Patients with renal artery stenosis
What are more affective as anti-hypertensive agents: Angiotensin receptor blockers or ACE inhibitors?
ACE inhibitors
What classes as stage 1 hypertension?
BP of 135/85 - 149/94
When would you start drug treatment for someone with stage 1 hypertension?
If there is: organ damage, CVD, Renal disease or diabetes
What classes as stage 2 hypertension?
BP of 150/95 or more
What are the therapeutic objectives when treating hypertension?
Reasonable blood pressure goals and reducing cardiovascular risk
What is meant by the term ‘drug clearance’ ?
Clearance is the measure of ability of the body to clear a drug
What is meant by the term ‘elimination half-life’ ?
The length of time required for the concentration of a particular drug to decrease to half of its starting dose in the body
What is meant by the term ‘time to peak plasma levels’ ?
Time required for a drug to reach peak concentration in plasma
Why might ACE inhibitors have a negative effect on eGFR and sodium potassium?
Angiotensin 2 is the major determinant of efferent vasoconstriction, it helps to maintain GFR when renal perfusion is low therefore blocking the action of Ang2 can cause acute renal failure
What are the main overall effects of thiazide-like diuretics?
Na+ and water loss from tubule lumen, decreased blood volume, decreased venous return and decreased cardiac output
