Adrenoceptor Antagonist Flashcards
Exam 4
Adrenoceptor antagonist overview
- reduce sympathetic stimulation
- used to manage glaucoma, migraines, cardiovascular disease, and urinary obstruction
- block alpha and beta receptors
Alpha adrenoceptor antagonist
- alpha blocker
- selective and nonselective
Phenoxybenzamine
- nonselective alpha blocker
- only noncompetitive/irreversible alpha blocker
- DOA is 3-4 days
- noncompetitive for NE and epi
- causes vasodilation and decreases BP
- clinical use: HTN in pheochromocytoma (adrenal medulla tumor)
Phentolamine
- nonselective alpha blocker
- competitive/reversible alpha blocker
- causes vasodilation, decreased BP
- clinical use: HTN in pheochromocytoma and to treat necrosis and ischemia after injection of alpha agonist
Selective alpha 1 blockers drugs
- Doxazosin (Cardura)
- Prazosin (minipress)
- Terazosin( Hytrin)
- Alfuzosin (uroselective alpha 1 blocker - uroxatral)
- Tamsulosin (uroselective alpha 1 blocker - flomax)
Selective alpha 1 blockers
- relax vascular and other smooth muscles (urinary bladder, urethra, and prostate)
- also cause vasodilation and decrease BP
- don’t cause as much reflex tachycardia compared to nonselective blockers
- ARD: hypotension (orthostatic), dizziness, sedation
Alpha antagonist effects on CVS
- prevent arteries from constricting by blocking alpha 1 and 2
- lower BP
- clinical use: HTN
Alpha antagonist effects on GU
- blockade of alpha 1: block smooth muscle contraction at base of bladder and prostate
- increase urine flow
- clinical use: BPH
Adverse reactions of alpha antagonist
- postural hypotension: lightheadedness and syncope
- reflex tachycardia
- miosis (pupil constriction)
- nasal stuffiness
Beta adrenoceptor antagonist
- beta blocker
- MOA: bind to receptor and block effect of endogenous catecholamine such as NE and epi
- high doses lose their selectivity and they will start to hit other receptors
Nonselective beta blockers
- Nadolol (Corgard)
- Pindolol (Visken)
- Propranolol (Inderal)
- Timolol (Timoptic)
Selective beta 1 blockers
- Acebutolol (Sectral)
- Atenolol (Tenormin)
- Esmolol (Breviblock)
- Metoprolol (Lopressor, Toprol XL)
Alpha and beta blockers
- Carvedilol (Coreg)
- Labetalol (Trandate)
Beta blocker effects on CVS
- decrease BP (decrease cardiac output and renin secretion)
- decrease HR
- decrease contractility
- decrease AV conduction
- clinical use: angina, MI, SVT, HTN, HF
Beta Blocker effects on respiratory
- beta 2 blockade increase airway resistance
- no clinical use
- avoid non-selective beta blockers in asthma
Beta blocker effects on eye
- beta blockade decreases aqueous humor production and IOP
- Clinical use: glaucoma
Beta blocker effects on hepatic
-decrease hepatic venous pressure gradient and portal hypertension
Beta blocker effects on metabolic effects
- beta blockade inhibits recovery from hypoglycemia (your sns kicks in when hypoglycemic)
- No clinical use, but care on meds that cause hypoglycemia (diabetics)
Local anesthetic effects of beta blockers
- no related to receptor blockade
- not an effect when taken orally, just topically
- effect you want to avoid when using the beta blocker topically in eye for glaucoma
- Timolol has no anesthetic effect - used in glaucoma
Other clinical uses of beta blockers
- prevention of migraine
- muscles tremors
- EtOH withdrawal
- anxiety: especially performance associated (gets rid of symptoms of anxiety but not the anxiety itself)
Beta blocker effects on CNS
- depression
- sedation
- sleep disturbances
- rarely psychotic reactions
Beta blocker effects on peripheral vascular disease
- beta 2 stimulation vasodilates blood vessels in leg
- blockers can block this and make peripheral vascular disease worse
Beta blocker effects on heart failure
- need beta 1 stimulation of hear to make pump harder
- blockers can treat heart failure, but also can make it worse
- keep pt off of blocker during acute phase, but can use during chronic therapy
- improve % of blood pumped from left ventricle with each heartbeat
- slow progression of heart failure
- decrease risk of death caused by MI and failure
