Anti-Adrenergics Drugs Flashcards
which drug is an irreversible blocker of alpha-adrenoceptors?
phenoxybenzamine (covalent bonding)– alpha1 and alpha2
what 2 drugs are alpha antagonists (non-selective)?
Phenotolamine
Phenoxybenzamine
what 2 drugs are selective alpha1 antagonists?
Prazosin
Tamsulosin
Postural hypotension is an adverse effect for which class of drugs?
alpha antagonists (i.e. Prazosin, Tamsulosin, Phentolamine, Phenoxybenzamine)
What are the main effects of giving an alpha-antagonist?
1) arterial and venous vasodilation
2) increase in HR (reflex sympathetic stimulation and increase of NE due to blockade of alpha-2 presynaptic adrenoceptors)
3) responses to catecholamines are impaired (i.e. norepi, epi)
4) bladder spinchter relaxation (improvement of urinary flow)
5) increased insulin release (due to blockade of alpha-2 receptors)
what would really high doses of phenoxybenzamine result in?
inhibition of cetecholamine reuptake and irreversible block of muscarinic, serotonergic and histaminergic receptors
what is the duration of action of pheonxybenzamine?
up to 7 days after discontinuation (time required before the number of alpha receptors return to normal)
what are the clinical uses of Prazosin?
1) urinary symptoms BPH (promotes peeing)
2) HTN
3) Raynaud’s disease
What are the clinical uses of Tamsulosin
1) urinary symptoms BPH (promotes peeing) - has more receptors on prostate specifically
2) HTN
What class of drugs can cause priapism and inhibition of ejaculation?
alpha antagonists
What 7 disorders can cause postural hypotension?
1) hypovolemia
2) idiopathic postural hypotension
3) addison disease
4) systemic mastocytosis
5) mitral valve prolapse syndrome
6) familial dysautonomia (Riley-Day syndrome)
7) multiple system atrophy (shy-Drager syndrome)
What is the main clinical uses of Phenoxybenzamine?
pheochromocytoma (used preoperatively and for management of inoperable or metastatic cases)
What is the main clinical use of Phentolamine?
1) pheocromocytoma (diagnosis)
2) tyramine syndrome
3) clonidine withdrawal
(anytime there is an emergency excess of circulating catecholamines)
what are 4 nonselective beta blockers?
propanolol
pindolol
timolol
sotalol
what are 3 selective B1 blockers?
atenolol
esmolol
metoprolol
what are two A-B blockers?
labetalol
carvedilol
what are the CVS effects of beta-blockers?
1) decreased heart contractility
2) decreased CO
3) increased perfusion of subendocardial region of heart
what effect do B-blockers have on vessels?
1) vasodilator
BP is not decreased in healthy ppl- only in those with hypertension!
B-blockers are especially contraindicated in people with what respiratory conditions?
Asthma and COPD (b-blockers cause bronchoconstriction but it can be lifethreatening in these individuals)
what effect do beta-blockers have in the eye?
decreased production of aqueous humor by ciliary epithelium
what are the metabolic/endocrine effects of beta-blockers?
1) Decrease release of Renin
2) decreased lipolysis
3) decreased glycogenolysis/ gluconeogenesis
4) decreased K+ uptake by skeletal muscle
5) blockade of catecholamine induced tremor
6) blockade of adrenergic activation due to hypoglycemia
what 3 beta-blockers act as local anestethics?
1) propanolol
2) pindolol
3) metoprolol
what beta-blocker is a weak b1 and b2 partial agonist?
Pindolol
what beta blocker has K+ channel blocking activity?
sotalol
What beta-blocker is used for A-fib?
Atenolol
What b-blocker has a short half life and is used in emergency siutations for a hypertensive crisis or surgery?
esmolol
What are the main clinical uses of beta-blockers?
1) HTN
2) cardiac arrhythmias
3) exertional angina
4) open angle glaucoma
5) acut eMI
6) hyperthyroid
7) hypertrophic cardiomyopathy
8) pheocromocytoma
9) social phobias
10) aortic dissection
what is the main pharmacological effects of labetalol and carvedilol (alpha/beta antagonists)
1) decreased TPR
minimal change in HR and CO. the decreased TPR causes reflex tachy that counteracts direct decrease in HR.
used for pregnancy induced hypertension
which beta blockers are lipid soluble?
propanolol
metoprolol
labetalol
what are the characteristics of lipid soluble beta blockers
low oral bioavailability, large first pass effect, large volume of distribution, cross BBB
what beta-blockers are hydrophilic?
atenolol
pindolol
esmolol
sotalol
AE’s of b-blockers?
1) peripheral vascular spasms
2) bradyarrhythmias
3) acute HF
4) sithdrawal effects after chornic use (don’t stop abruptly)
5) insomnia, dizziness, nightmares
6) diarrhea
7) bronchoconstriction
8) sexual dysfunction (esp after chronic use)
9) increased probability of hypoglycemic reactions
10) hypertensive crisis
11) hyperkalemia
12) skin rashes
Major contraindications of b-blockers
1) abrupt discontinuation
2) asthma/COPD
3) bradyarrhythmias
4) DM
5) acute cardiac failure
6) depression
7) elderly (unpredictable)
what is an indirect acting anti-adrenergic drug?
metyrosine
what is the MOA of metyrosine?
inhibition of tyrosine hydroxylase (rate-limiting enzyme in catecholamine biosynthesis)
what is the clinical use of metyrosine?
preop prep of patients for pheochromocytoma resection
adjuvant to alpha-blocker in patients with inoperable pheochromocytoma
