SELECTIVE-DIRECT ACTING AdRENERGIC AGONISTS

Question 1

Phenylephrine (neo-synephrine)

Answer 1

ALPHA 1- SELECTIVE AGONIST

• Activates alpha adrenergic receptors on vascular smooth muscle

–> INCREASE BP and INCREASE Total peripheral resistance

• Activates Beta receptors ONLY AT MUCH HIGHER CONC
• USES:
• antihypotensive
• paroxysmal atrial tachycardia
• nasal decongestant
• mydriatic

Question 2

Clonidine (catapres) and alpha-methyldopa (aldomet)

Answer 2

ALPHA 2- SELECTIVE AGONIST

• Mech of action
• activate central alpha2 receptors –> decrease central sympathetic outflow –> DECREASE BLOOD PRESSURE
• Uses: Systemic hypertension
• ADVERSE EFFECTS: dry mouth, sedation, hypotension

Question 3

Apraclonidine (lodipine) and Brimonidine (alphagan)

Answer 3

ALPHA 2-SELECTIVE AGONIST

• Mech of action:

–> decrease aqueous humor production –> decrease intraocular pressure

• USES = GLAUCOMA (NO HYPOTENSIVE EFFECT)
• ADVERSE EFFECTS

–> Dry mouth, sedation, hypotension

Question 4

Metaproterenol (metaprel)

Answer 4

BETA 2-SELECTIVE AGONISTS

• Resistant to methylation by COMT
• Beta2- selective (less than albuterol or terbutaline)
• USES

–> long-term treatment of obstructive airway disaeses, asthma

–> acute bronchospasm

Question 5

Terbutaline (bricanyl)

Answer 5

BETA 2- SELECTIVE AGONIST

• Not a substrate for COMT METHYLATION
• USES:

–> long-term tx of obstructive airway diseases

–> acute bronchospasm

–> emergency tx of status asthmaticus (IV use)

Question 6

Albuterol (ventolin, salbutamol)

Answer 6

BETA 2- SELECTIVE AGONIST

• USES:

–> treat bronchospasm similar to those of terbutaline

–> oral use

–> delay preterm labor

Question 7

RITODRINE (yutopar)

Answer 7

BETA 2-SELECTIVE AGONIST
- Developed specifically for use as a UTERINE RELAXANT

• USES

–> arrest premature labor

–> PROLONG PREGNANCY

Question 8

what are the adverse effects of Beta2-SELECTIVE AGONISTS

Answer 8

• RESULT FROM EXCESSIVE ACTIVATION OF BETA-RECEPTORS

–> Tachycardia

• pts with coronary artery disease or preexisting arrhythmias are at high risk
• adverse cardiovascular effects are increased if MAO INHIBITORS are used

–> Increase plasma glucose, lactate and free fatty acids

–> decreased plasma K+ –> important in patients with cardiac disease, particularly those taking digoxin and diuretics

**ADVERSE EFFECTS REDUCED WITH INHALATION THERAPY**

Question 9

FENOLDOPAM (corlopam)

Answer 9

D1 - SELECTIVE AGONISTS
- some stimulation of alpha2 adrenoceptors –> feedback inhibiton of NE release

EFFECTS:

–> renal, mesenteric, peripheral and coronary VASODILATION

–> renal blood flow is maintained and natriuresis is promoted

USE: HYPERTENSIVE CRISIS

ADVERSE EFFECT = Hypotension