CVS Drugs 61 to 70
Describe the pharmacodynamics of propranolol that make it useful in thyrotoxicosis.
Prompt: What are the cardiovascular effects?
- B-blocker – competitive non selective antagonist of both B1 and B2 receptors
- CVS effects:
- Decreased BP
- Decreased HR (especially rate control of AF)
- Both negatively inotropic and chronotropic
- Decreased catecholamine effects which are prominent in hyperthyroidism
- Inhibition of perihperial conversion of thyroxine (T4) to triiodothyronine (T3) – this is especially evident with propranolol compared with other B-blockers
- Has Na-channel blocking action (‘membrane stabilisation‘)
- Bold and 2 CVS effects to pass.
What are the adverse effects of propranolol?
- CVS – bradycardia, hypotension, worsening of CCF, worsening ischaemia in PVD, QRS widening and arrythmias in toxicity
- CNS – sedation, depression, dreams, coma/seizure/delirium in toxic doses
- Respiratory – worsening asthma/COPD
- Other – decreased exercise tolerance, fatigue, impotence, decreased libido, masks symptoms of hypoglycaemia
- 1 example from each bold system to pass.