Nonselective Alpha & Beta Agonists

non-selective drugs

They work on the same receptors but not to the same degree - therefore they have different indications

In general, they work to:

         - ↑ HR, vasoconstrict, dilate bonchi,
         - promote glycogenolysis (breakdown of glycogen)
         - dilate pupils, inc sweating

Indications

• Tx hypotensive shock (esp dopamine)
• bronchospasm & some types of asthma

Contraindications

• Pheochromocytoma (adrenal tumor —> inc catecholamine secretion —> major inc HR & BP)
• Tachy-arrhythmias or V-Fib
• Hypovolemia
• Halogenated hydrocarbon general anesthetics

Cautions

• PVD – could be exacerbated by systemic vasoconstriction
• pregnancy & lactation

Adverse Effects

• Arrhythmias, hypertension, palpitations, angina
• dyspnea
• N/V
• Headache, sweating

Kinetics

• Rapidly absorbed after injection or passage through mucous membranes
• Metabolized in the liver and excreted in the urine

Drugs
1. Dobutamine (Dobutrex)

• preference for B1 receptors –> therefore indicated for CHF
• it can inc myocardial contractility (+ inotrope) w/o much change to rate; does not inc O2 demand of the heart, while most other sympathomimetics do

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2. Epinephrine (Adrenaline, Sus-Phrine)

• indicated for shock, glaucoma, asthma/COPD, anaphylactic reactions
• can also prolong effects of local anesthetics

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3. Norepinephrine (Levophed)

• indicated for shock
• used during cardiac arrest (V-fib) to get sympathetic activity

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4. Metaraminol (Aramine)

• synthetic agent similar to norepinephrine

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Big Guns:
1. Dopamine (Intropin)

• Tx hypotensive shock
• ↑ HR, ↑ BP
• maintains renal perfusion (maintains UO / ↑ Na & fluid output)

       - most vasoconstrictors aren't able to dilate renal arterioles

Nursing Considerations for Dopamine:

• monitor BP, HR, peripheral pulses, UO
• precise measurement essential for accurate titration of dosage
• report the following to physician:

       - dec urine flow in absence of hypotension
       - ascending tachy, dysrhythmias, disproportionate rising diastolic (marked dec in Pulse Pressure), S&S peripheral ischemia (pallor, cyanosis, coldness, pain, numbness/burning, mottling)

• monitor for extravasions

       - have phentolamine on hand – antidote

• monitor for effectiveness - 

       - improved VS & signs of good vital organ perfusion:
       - (loss of pallor, inc toe tmp, good cap refill, reversal of confusion)

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2. Ephedrine (pretz-D)

• Tx seasonal rhinitis, hypotensive episodes, (recreational use)
• causes cardiac stimulation, vasoconstriction, bronchodilartion
• stimulates Norepinephrine release
• crosses blood brain barrier (BBB) –> CNS stimulation –> used for narcolepsy & depression, (used illegally as sports performance enhancer)
• form of the drug (Pseudoephedrine) used as nasal decongestant

Nursing Considerations for Ephedrine

• find out pt's OTC med use / education about inadvertent overdose
• monitor AE:
•        CNS: anxiety restlessness
•        CV: tachy, palpitations
•        GU: difficult/painful urination, acute urinary retention (esp. older men w/ prostatitis)

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Drug Interactions

• inc effects Tricyclic antidepressants (TCAs) and MAOI’s
•        MAOI inhibits monoamine oxidase which is needed to break down Epi & NE

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Nursing Mgmt for All A&B Agonists

• Monitor kidney/liver function, serum electrolytes, I&O, VS, ECG
• Herbs to avoid: Ma Huang, guarana, caffeine (↑ BP, stroke death)
• ask bout OTC cold, allergy, & diet pills use (↑ BP, stroke death)
• Avoid extravasation
• Aseptic technique when administering ophthalmic & nasal agents
• Monitor light exposure to prevent sensitivity to light from pupil dilation
• Encourage voiding prior to med admin to prevent urinary retention due to sphincter contraction
• Encourage relaxation to alleviate feelings of tension and anxiety
• Usually administered systemically for hypovolemic – hypotensive shock in an ICU (esp Dopamine) so pt needs constant monitoring
• monitor systemic effect of nose drops due to excessive dosage due to rapid absorption through nasal mucosa