Adrenoreceptor antagonists

Alpha blockers: decrease in vascular peripheral R; often cause orthostatic hypotension and reflex tachycardia; miosis; nasal stuffiness

a) alpha-1 selective:used in primary hypertension and benign prostatic hyperplasia; decrease the R to the flow urine ( receptor expressed in the base of the bladder, used in treatment of urinary retention

*PRAZOSIN (blocks aplha1 but not alpha2):lower BP. Used in hypertension, benign prostatic heprplasia. Can cause othostatic hypotension

*DOXAZOSIN (as prazosin)

*TERAZOSIN (as prazosin)

*TAMSULOSIN: blockage may relax prostatic smooth muscles more than vascular smooth muscle. Used in benign prostatic hyperplasia

*SILODOSIN: used in prostatic hyperplasia

b) alpha-2 selective:

*YOHIMBINE: elicits increased central symp.activity; increases norepinephrine release; increases BP & HR. Used in hypotension, male erectile dysfunction. May cause anxiety, tachycardio, GI upset

c)nonselective: used in treatment of pheochromocytoma

- reversible: dissociate from receptors and the block may be reversed with high concentrations of AGONISTS, shorter lasting

*PHENTOLAMINE: blocks alpha mediated vasoconstriction, lowers BP, Increases HR (baroreflex). Used in pheochromacytoma

-irreversible : do not dissociate from the receptor, longer lasting

*PHENOXYBENZAMINE: lowers BP, HR rise due to baroreflex activation. Used in pheochromacytoma and in high catecholamine states (forms a reactive ethyleneimonium intermediate that covalently binds to alpha recerptor, resulting in irrev.blockade)long duration ( 14-48hrs); slightly selective fr alpha1; inhibits reuptake of released norepinephrine; blocks histamine, acetylcholine and serotonin receptors as well as alpha receptors. Causes little fall in BP in normal supine individuals; reduces BP when symp. tone is high; cardiac output may be increased

d) alpha + beta blockers

*LABETALOL: more to beta than alpha1; lowers BP with limited increase in HR. Used in hypertension. Less tachycardia than other alpha 1 agents

Beta blockers:

a) beta-1 selective

*ATENOLOL: lower HR and BP; reduce renin; may be safer in asthma. Used in angina pectoris, hypertension, artyhmias. Can cause bradycardia, fatigue, cold hands, less danger of bronchospasms

*ALPRENOLOL (as atenolol)

*METOPROLOL (as atenolol)

*NEBIVOLOL (as atenolol)

*BETAXOLOL ( as atenolol)

*ESMOLOL: very brief in cardiac beta blockade; used in rapid control of BP and arrythmias, thyrotoxitosis, myocardial ischaemia intraoperatively

b)beta-2 selective

*BUTOXAMINE: increases peripheral R; no clinical indications; can provocate asthma

c) nonselective

*PROPRANOLOL: lower BP & HR; used in hypertension, angina pectoris, arrythmias, migraine, hyperthyroidism. Can cause bradycardia, worsen asthma, fatigue, vivid dreams, cold hands

*NADOLOL ( as propranolol)

*TIMOLOL (as propranolol)

*PINDOLOL: lower BP, modestly lover HR; used in hypertension, arrythmias, migraine, MAY AVOID WORSENING OF BRADYCARDIA!, can cause fatigue, vivid dreams, cold heands

*ACEBUTOLOL (as pindolol)

*CARTEOLOL (as pindolol)

*BOPINDOLOL (as pindolol)

*OXPRENOLOL (as pindolol)

*CELIPROLOL (as pindolol)

*PENBUTOLOL ( as pindolol)

*CARVEDILOL => ALL ARE USED IN HEART FAILURE, MORE TO BETA THAN ALPHA 1 BLOCK

*MEDROXALOL

*BUCINDOLOL

TYROSINE HYDROXYLASE INHIBITOR

*METYROSINE: blocks tyrosine hydroxylase; reduces synth. of dopamine, norepinephrine, epinephrine; lowers BP, may elicit extrapyramidal effects in CNS ( due to low dopamine). used in pheochromacytoma. Can cause orthostatic hypotension, extrapyramidal eymptoms, crystalluria