Pharmacology Zhu (Alpha and Beta Agonist and Antagonists)

Cardiogenic shock (acute heart failure)
Dopamine(B1) and dobutamine (B1) Positive ionotropic agents

Chronoic Orthostatic hypotension
Midodrine (A1)

Therapeutic uses of Phenylephrine (A1>A2>>>>B) (Midodrine)
Nasal decongestant, pressor agent, dilate pupils (mydriasis), provide local vasoconstriction, postural hypotention (midodrine)

Antihypertension, lowers cAMP and Ca++ levels, A2 type agonist

Directly activates B1 receptor, greater ionotropic than chronotropic effects, minimal changes in HR and systolic BP, used to improve myocardial function in heart failure (B1>B2>>>A)

(B1=B2>>>A), Increased cardiac contractility and heart rate (B1), vasodilation in perpheral with slight decrease in mean BP (B2), marked drop in diastolic BP, muscle relaxation in bronchial and GI smooth muscle (B2), Therapeutic use is as a bronchodilator and as a cardiac stimulant for heart block or sever bradycardia
Isoproterenol (B1=B2>>>>A)

Dilate tracheal and bronchial smooth muscles (B2 agonists)
Albuterol, Terbutaline (B2 agonists)

Dilate uterus SM (B2 agonist)
Terbutaline (B2 agonist)

Acts by releasing NE, CNS stimulant, Resistant to COMT metabolism, Therapeutic uses are: mood elevation, treatment of narcolepsy, treatment of ADHD
Amphetamine like drugs: Modafinil (sleep-deferring action for narcolepsy), Methylphenidate (used in children ADHD)

MAO Inhibitor Drugs: Antidepressants and Parkinson’s Disease
Phenelzine (antidepressant), Selegiline (parkinson’s)

Pharmacologic effects: Potent block dopamine transporter, block norepinephrine transporter, block sodium channels as a local anesthetic, potent CNS stimulant, euphoria, increase BP and HR, hallucinations, delusions, seizure and death

Mydriatic Agent
Phenylephrine (A1)

Treatment in glaucoma as it decreases IOP and aqueous secretions
Apraclonidine (A2)

Genitourinary Applications, suppresses premature labor
RItodrine, Terbutaline (B2)

Toxicity of selective a1 adrenergic agonists

Toxicity of b-receptor stimulant drugs
tachycardia, arrhythmias

Important organs that receive dual innervation (5)
heart, eye, lung (bronchial sm), GI tract sm, genitourinary tract sm

Inhibits tyrosine hydroxylase

Inhibits VMAT’s (vesicular monoamine transporter)

Inhibits vesicle release in adrenergic transmission

Inhibit’s NET in adrenergic transmission
Cocaine and TCA’s

Inhibits choline transporter in cholinergic transmission

Inhibits Vesicle-associated transporter (VAT) in cholinergic transmission

Inhibit’s SNAP-25 and syntaxin (snare proteins)
Botulinum toxin

Reversible competitive alpha-receptor antagonists (3)
Phentolamine, prazosin, labetalol

Irreversible non-competitive alpha-receptor antagonist (1)

Pharmacologic effects of alpha blockers
lower vascular resistance and pressure, side effect is baroreceptor-mediated tachycardia for nonselective alpha blockers, epinephrine reversal in large epinephrine doses, nasal stuffiness, miosis, may be used in pt’s to decrease difficulty in urination (improve continence)

Irreversible alpha blocker antagonist, A1>A2 selectivity, inhibits reuptake of released NE, blocks histamine, acetylcholine, serotonin receptors, therapeutic use is for pheochromocytoma, adverse effects: postural hypotension, tachycardia, nasal stuffiness, inhibition of ejaculation

Blocks A1 and A2 receptors, reversible inhibitor, also used in pheochromocytoma, side effects: cardiac stimulation due to blocade of presynaptic a2 receptors in sympathetic nerves in heart (tachycardia, arrhythmias, ischemia will occur)

(A1>>>>>A2) antagonist, leads to relxation of vascular smooth muscle due to blockade of A1 receptors, less tachycardia side effect seen b/c it’s more A1 selective, therapeutically useful in hypertension and BPH
Prazosin, Terazosin, Doxazosin, Tamsulosin

Tumor from adrenal medulla or sympathetic ganglion cells, treated by nonselective alpha antagonists, clinical symptoms include HT, headache/vomiting, palpitations, sweating/pallor, flushing/chest pain
pheochromocytoma (treatment for inoperable pt’s will be metrosine)

Used in hypertensive emergencies

Used in chronic hypertension
Prazosin, doxazosin, terazosin

Used in pheochyomocytoma
Phenoxybenamine, metyrosine

Used in peripheral vascular disease (raynaud’s phenomenon)
prazosin, phenoxybenzamine

Used in BPH
prazosin, doxazosin, terazosin

General adverse effects of alpha antagonists
Postural hypotension and tachycardia, nasal stuffiness and inhibition of ejaculation can also occur

Nonselective beta blockers (3)
propranolol, nadolol, timolol

Selective B1 blockers
Metoprolol, Atenolol, Esmolol

Mixed action beta blockers
Pindolol and Acebutalol (both have b2 partial agonist abilities), labetalol (has b1 and a1 block but b2 stimulation), carvedilol (has nonselevtive b and a1 block)

Type of beta receptor found in heart muscle

Type of beta receptor found in vasculature, bronchi, produces smooth muscle relaxation

How does a beta blocker alter epinephrine action?
will decrease cardiac contractile force and heart rate, but not interfere with BP b/c vasoconstriction is not blocked

Effects of b2 blocker on the eye
Will reduce aqueous humor production, reduce IOP in glaucoma

Effects of B2 blocker on metabolic and endocrine
will inhibit glycogenolysis in liver and mask premonitory symptoms (tachycardia/tremor) of hypoglycemia from insuline overdosage, will also causes VLDL to increase and HDL to decrease

(B1=B2), B blocker
-long acting, 24h
– block Muscarinic and Serotonin receptors
– Used for
Hypertension, angina, tachyarrhythmias
Myocardial infarction, essential tremor
Migraine prophylaxis
– Airway Diseases
– Bradycardia, Severe hypotension
– Uncontrolled congestive heart failure

B1 selective antagonist, may be safer for patients who experience bronchoconstriction responses (asthma) to propranolol, therapeutically useful in treating hypertension, MI
Atenolol, Acebutolol, Metoprolol

Clinical application of beta blockers (8)
1) HT
2) ischemic heart diseases
3) Cardiac Arrhythmias
4) Heart Failure (metoprolol and carvedilol)
5) Hypertrophic obstructive cardiomyopathy
6) Glaucoma (timolol, nadolol – by reducing production of aqueous humor)
7) Hyperthyroidism (propranolol)
8) Neurologic diseases

Uses of propranolol (b1 and b2 blocker)
HT, glaucoma, hyperthyroidism, angina pectoris, MI

Uses of Nadolol/Timolol (B1 and B2 blocker)
HT, glaucoma

Uses of acebutolol, atenolol, esmolol, metoprolol (b1 blocker)
HT (especially in pt’s with COPD)

Uses of Pindolol (b1 and b2 blocker)

Uses of carvedilol and labetalol (a1, b1, and b2 blocker)

Clinical toxicity/side effects of beta blockers
Cardiovascular: bradycardia, CHF, abrupt dicontinuation may cause angina. Pulmonary: pulmonary bronchoconstriction, contraindicated in asthma.
CNS: fatigue and depression.
Metabolic effects:delayed recovering from insulin-induced hypoglycemia, increased blood lipid levels (VLDL)

Propranolol *Nonselective *Low dose-dependent bioavailability Negligible effects on alpha and muscarinic receptors *Nitric Oxide partial agonist activity at beta-receptors Metoprolol *Beta-1 selective (preferable in pts. with diabetes or PVD) Better for pts. who experience bronchoconstriction w/ propranolol but still use …

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What is a beta blocker? class of drugs that antagonizes b-androgenic receptors (sympathetic), reduces BP, stabilizes cardiac arrhythemia; off label treatments include anxiety, tremors related to Parkinson’s, and migraines How do beta blockers work? inhibi actiity and decrease receptor sites …

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Atomoxetine Cocaine like drug, selective NE reuptake inhibitor used in the management of ADHD. Methylphenidate Amphetamine like Drug, but with greater affect on DA then on NE and the preferred drug for ADHD because of reduced ANS effects. WE WILL …

MOA non-selective beta blocker Block the effects of epinephrine and norepinephrine from beta-adrenergic receptors throughout the body (beta 1 and 2); decrease the heart rate and force of heart contractions, which leads to decreased blood pressure; dilate blood vessels and …

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