ADRENERGICS


Actions and uses:

Adrenergic drugs stimulate the sympathetic nervous system by mimicking sympathetic neurotransmitters such as norepinephrine and epinephrine. They act on adrenergic receptor sites located in the cells of muscles, such as the heart, bronchiole walls, GI tract, urinary bladder, and ciliary muscle of the eye. Although there are many adrenergic receptors, the four main receptors are alpha1, alpha2, beta1, and beta2. When stimulated these receptors work to increase blood pressure, increase bronchial tubes, and increase heart rate.

Effects of Adrenergic Receptors:
Alpha1 – Force of heart contraction is increased; vasoconstriction increases blood pressure, dilation of pupils occurs; decreased secretion from salivary glands; increased urinary bladder relaxation and urinary sphincter contraction.

Alpha2 – Norepinephrine release inhibited; blood vessels dilate; produces hypotension; gastrointestinal motility and tone decreased.

Beta1 – Increases hear rate and force of contraction; rennin secretion increases, which, in turn, increases blood pressure.

Beat2 – Bronchioles dilate; promotes gastrointestinal and uterine relaxation; promotes increase in blood sugar through glycogenolysis in the liver; blood flow in skeletal muscles increases.


Side effects and adverse effects:

Side effects can occur when the drug dosage in increased or the drug is nonselective causing more responses to occur than are desired. Anorexia, nausea, vomiting, nervousness, tremors, agitation, headache, pallor, insomnia, syncope, dizziness and restlessness are common side effects. Palpitations, tachycardia, dyspnea, and hallucinations are adverse reactions that must be watched. Ventricular fibrillation, pulmonary edema, and cardiac dysrhytmias are life threatening effects.

Nursing implications:

  • Check urinary output and assess for bladder distension. Urinary retention can result from high dosages or continuous use of adrenergic drugs.
  • Monitor IV site frequently when administering norepinephrine bitartrate or dopamine. Infusion of these drugs causes tissue necrosis. These drugs should be diluted in IV fluids. If an antidote is needed phentolamine mesylate 5 to 10 mg, diluted in 10 to 15 ml of saline should be infiltrated into the area.
  • Offer food when giving adrenergic drugs to avoid nausea and vomiting.
  • Evaluate blood glucose levels for increases.


Adrenergic Youtube Video



ADRENERGIC BLOCKERS

Actions and uses:
Adrenergic blockers are drugs that block the effects of adrenergic neurotransmitters. They act as antagonists to adrenergic agonists by blocking the alpha- and beta-receptor sites. Most of these block either the alpha- or the beta-receptor by blocking the effects of neurotransmitters either directly occupying the alpha- or bet-receptor or indirectly by inhibiting the release of neurotransmitters norepinephrine and epinephrine. The three sympatholytic receptors are alpha1, beta1, and beta2.
Effects of Adrenergic Blockers:
Alpha1 – Vasodilation: decrease blood pressure; may cause reflex tachycardia; constriction of pupil occurs; ejaculation is suppressed; contraction of smooth muscle in bladder neck and prostate gland is reduced.
Beta1 – Heart rate decreases; force of contractions is reduced.
Beta2 – Bronchioles constrict; uterus contracts; inhibits glycogenolysis, which can decrease blood sugar.



Side effects and adverse effects: Common side effects associated with beta blockers are bradycardia, palpitations, hypotension, headache, dizziness, hyperglycemia, hypoglycemia, and bronchospasm.. General side effects of alpha-adrenergic blockers are, flushing, hypotension, impotence or decreased libido, and depression. Life threatening reactions include agranulocytosis, pulmonary edema, and cardiac dysrhytmias. Side effects are usually dose related.

Nursing implications:

· Determine if client has diabetes and receives a beta-adrenergic blocker; insulin dose or oral hypoglycemic may need to be adjusted.
· Have glucagon available. Clients that take beta-blockers do not have normal compensatory mechanisms while in shock states. To resuscitate these clients, glucagon must be given in high doses to counteract sympatholytic effects of beta-blockers.
· Note complaints of excessive dizziness or light-headedness.
· Report complaints of stuffy nose, Vasodilation results from the use of alpha-adrenergic blockers, which can cause nasal congestion to occur.


Adrenergic Blocker Youtube Video

REFERENCES:
Kee, Joyce L., Hayes, Evelyn R., & McCuistion, Linda E. (2009). Pharmacology: A Nursing Process Approach (6th ed.), (pp. 267-280). St. Louis, Missouri: Saunders Elsevier

Edited by Lori Campbell