Adrenergic Drug Class

Adrenergic Drugs

Adrenergic drugs affect the sympathetic nervous system — the body’s “fight or flight” response.

act on adrenergic receptors:

• Alpha (α) receptors (CONSTRICT)

• Beta (β) receptors(DILATE)

These drugs can either:

• Stimulate the receptors → agonists / sympathomimetics

• Block the receptors → antagonists / blockers

Adrenergic Agonists

speed things up:

• Increase heart rate

• Raise blood pressure

• Open airways

• Increase alertness

GO DRUGS

Adrenergic Antagonists

slow things down:

• Lower blood pressure

• Slow heart rate

• Relax vessels

SLOW DRUGS

Direct Sympathomimetics

stimulate adrenergic receptors and act like epinephrine/norepinephrine in the body.

examples

• epinephrine

• norepinephrine

• dopamine

• dobutamine

Epinephrine (Direct Sympathomimetics)

treats cardiac arrest and severe hypotension as well as bronchospasm in asthma and anaphylaxis

Stimulates:

• α1 → vasoconstriction (HIGH DOSES)

• β1 → increases HR (LOW DOSES)

• β2 → bronchodilation (LOW DOSES)

Nursing Side Effects

• Tachycardia

• Hypertension

• Anxiety

• Tremors

Norepinephrine (Direct Sympathomimetics)

Used as a pressor in the emergency treatment of severe hypotension and shock

stimulates:

• α1 → strong vasoconstriction

• β1 → increases BP and contractility

Nursing side effects

• Monitor BP closely

• Can cause tissue necrosis if IV infiltrates

Dopamine (Direct Sympathomimetics)

Used as a pressor in the emergency treatment of severe hypotension and shock

Dose dependent:

• Low dose → improves kidney perfusion

• Moderate → increases heart contractility

• High → vasoconstriction

Side Effects

• arrhythmias

• Tachycardia

• HYPERTENSION

Dobutamine (Direct Sympathomimetics)

Used as a pressor in the treatment of cardiogenic shock

β1 stimulation:

• Stronger heart contractions

Side Effects

• Increased HR

• arrhythmias

• HYPOTENSION

Indirect Sympathomimetics

increase norepinephrine levels indirectly BY release of norepinephrine OR Prevent norepinephrine breakdown/reuptake

EXAMPLES

• Ephedrine

• cocaine

Ephedrine

Releases norepinephrine and mildly stimulates receptors.

used for NASAL DECONGESTANT and HYPOTENSION in surgery or anesthesia

Side Effects

• Nervousness

• Hypertension

• Tachycardia

cocaine

Blocks norepinephrine reuptake → excess stimulation.

Dangerous Effects

• Stroke

• MI

• Severe hypertension

Adrenergic Agonists

drugs that stimulate the sympathetic nervous system by activating adrenergic receptors (a1, a2, b1, b2, b3)

examples

1. Phenylephrine

2. Midodrine

3. Clonidine

4. Isoproterenol

5. Albuterol

6. Terbutaline

7. Methyldopa

Phenylephrine (Alpha Adrenergic Agonists)

Used to treat severe hypotension and shock AND nasal congestion. DILATION I EYE EXAMS

α1 agonist → vasoconstriction

side Effects

• Headache

• Reflex bradycardia

Midodrine (Alpha Adrenergic Agonists)

Used to treat orthostatic(upright) hypotension, used in advanced hepatic disease

• α1 agonist → increases vascular tone

Nursing Notes/sides

• Monitor BP lying down and standing

• Supine hypertension

Clonidine (Alpha Adrenergic Agonists)

treats hypertension

• α2-agonist in CNS → decreases sympathetic outflow (tells brain to stop sending stress signals)

Sides effects

• Rebound hypertension (IF WITHDRAWN QUICKLY)

• bradycardia

• sedation

Isoproterenol (Beta Adrenergic Agonists)

Used to treat torsades de pointes in conjunction with magnesium.

Occasionally used in the treatment of cardiac arrest or complete heart block or (rarely) to treat severe bronchospasm

• β1 + β2 agonist

Effects

• Increases HR

• Bronchodilation

side effects

• cardiac tachyarrhythmias

• anxiety

• pulmonary edema

Albuterol (SIMILAR Pirbuterol; bitolterol) (Beta Adrenergic Agonists)

Treatment of asthma. Also used to treat hyperkalemia when given in high doses

• β2 agonist → bronchodilation

Nursing Notes

• Rescue inhaler

• Opens airways quickly

side effects

• Tachycardia

• remor

• anxiety

• SIDE EFFECTS MINIMAL IN INHALER USE

Terbutaline (SIMILAR Ritodrine) (Beta Adrenergic Agonist)

Used to delay preterm labor by reducing uterine contractions. Can also be used to treat bronchospasm during status asthmaticus (life-threatening asthma attack)

• β2 agonist

Side Effects

• Tachycardia

• Tremors

Methyldopa (Alpha Adrenergic Agonists)

Treatment of moderate hypertension

• α2 agonist → lowers sympathetic stimulation

Side Effects

• Drowsiness

• Orthostatic hypotension

Adrenergic Antagonists (Blockers)

These drugs block adrenergic receptors alpha or beta

EXAMPLES

• Phenoxybenzamine

• Tamsulosin

• Beta Blockers

• Metoprolol

Phenoxybenzamine (Adrenergic Antagonists (Blockers)

Treatment of pheochromocytoma(a rare, usually noncancerous (benign) tumor that grows in the adrenal glands)

• Blocks α receptors → vasodilation

Side Effects

• Orthostatic hypotension

• Reflex tachycardia

• nasal congestion

• inhibition of ejaculation

Tamsulosin (Adrenergic Antagonists (Blockers)

(SIMILAR Prazosin; doxazosin; tamsulosin; alfuzosin.)

Treatment of hypertension.

Treatment of benign prostatic hypertrophy (terazosin, doxazosin, tamsulosin)

• Selective α1 blocker in prostate AND bladder (Relaxes the urinary tract.)

side effects

• First-dose” syncope

• Dizziness

• Orthostatic hypotension (drop in pressure when standing up after sitting down)

Beta Blockers

slow heart rate and lower BP

END IN OLOL

Propranolol (SIMILAR Nadolol; pindolol; timolol.) (Adrenergic Antagonists (Blockers)

Uses include treatment of cardiovascular disorders (hypertension, angina), AND treatment of tachycardia associated with hyperthyroidism

treatment of chronic migraines (causes cerebral vasodilation)

• Propranolol is a β1- and β2-receptor antagonist (Nonselective β blocker)

Side Effects

• Bradycardia

• Fatigue

• Bronchoconstriction

• fasting hypoglycemia

Nursing Notes

• Check HR and BP before giving

Metoprolol (Adrenergic Antagonists (Blockers)

SIMILAR (Atenolol; esmolol; acebutolol; bisoprolol; betaxolol; nebivolol.)

Used in the treatment of hypertension, tachycardias, and coronary artery disease, especially in patients with diabetes

Selective β1 blocker (antagonist)

Side Effects

• Mild bronchoconstriction (avoid in asthmatics if possible)

• Bradycardia

• Hypotension

• Fatigue

agonist vs antagonist

Agonists bind to cellular receptors and STIMULATE THEM

Antagonists also bind to receptors, but BLOCK them

Sympathetic Nervous System

your alert system that quickly prepares your body to face emergencies. automatically alerts to cause physiologic responses to
prepare you for fight or flight.

 ⮚ Pupil dilation
⮚ Inhibit salivation
⮚ Relaxes bronchi
⮚ Increased heart rate
⮚ Slows digestion
⮚ Reduces intestinal muscles
⮚ Adrenaline production
⮚ Reduces blood flow

Parasympathetic Nervous System

resting and digesting” system which helps to maintain the normal body functions without any conscious effort

⮚Pupil constriction
⮚Stimulated saliva
⮚Bronchi constriction
⮚Slow heart rate
⮚Stimulates production of bile
⮚Stimulates digestion
⮚Intestinal muscle relaxation
⮚Causes an erection