Actions and Uses
Adrenergic drugs stimulate the adrenergic nerves directly by mimicking the action of norepinephrine or indirectly by stimulating the release of norepinephrine. These drugs are used to combat life-threatening disorders, which include acute attacks of bronchial asthma, shock, cardiac arrest, and allergic reactions. In addition these drugs are used in nasal decongestants and appetite suppressants.
There are at least two adrenergic receptor sites (alpha or beta). Norepinephrine activates primarily alpha receptors and epinephrine activates mainly beta receptors.

Alpha receptor stimulation is associated with constriction of small blood vessels in the bronchial mucosa and relaxation of smooth muscles of the intestinal tract.
Alpha blockers relax certain muscles and help small blood vessels remain open. They work by keeping the hormone norepinephrine from tightening the muscles in the walls of smaller arteries and veins. This improves blood flow and lowers blood pressure

Beta receptor activation relaxes bronchial smooth muscles which cause the bronchi of the lungs to dilate.
Beta blocking drugs are given to patients so that the heart rate and blood pressure are reduced, and the heart will pump with less intensity. This will also reduce the oxygen needs in the heart


Side effects and adverse effects
Alpha blockers may have what's called a "first-dose effect." meaning when you first begin the medication you may develop low blood pressure and dizziness, which can make you suddenly faint when you rise from a sitting or lying position. Other side effects include headache, pounding heartbeat, nausea, weakness, weight gain and small decreases in LDL cholesterol the bad cholesterol. Alpha blockers can also increase or decrease the effects of other medications you take.

Adverse effects that are associated with the use of beta blockers include nausea, diarrhea, bradycardia, hypotension, heart failure, heart block, fatigue, dizziness, abnormal vision, decreased concentration, hallucinations, insomnia, and nightmares. Mixing alpha and beta antagonist therapy is also commonly associated with orthostatic hypotension.


Nursing Implications
- Use cautiously in patients that have a history of hypertension
- Monitor ECG, blood pressure, cardiac output and urine output
- Monitor electrolytes, some drugs may lower potassium levels
- Offer food when giving adrenergic drugs, as it could nausea and vomiting


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Sources
Ophardt, C (2003). Adrenergic Drugs I. Retrieved July 1, 2009, from Virtual Chembook Web site: http://www.elmhurst.edu/~chm/vchembook/663adrenergic.html
Cahill, M. (Ed.). Illustrated Handbook of Nursing Care. (1998). Cardiovascular Care. (1st ed., Springhouse: Springhouse Corporation.