McKenna's Pharmacology for Nursing, 2e

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P A R T 5  Drugs acting on the autonomic nervous system

α-SPECIFIC ADRENERGIC AGONISTS a -specific adrenergic agonists (Table 30.2), or a -agonists, are drugs that bind primarily to α -receptors rather than to β -receptors. Drugs belonging to this class include clonidine ( Catapres ) and phenylephrine ( Abalon , Neo-Synephrine ). Therapeutic actions and indications Therapeutic effects of the α -specific adrenergic agonists result from the stimulation of α -receptors within the SNS (see Figure 30.2). The uses are varied, depending on the specific drug and the route of administration (Table 30.2). Phenylephrine, a potent vasoconstrictor and a 1 -agonist with little or no effect on the heart or bronchi, TEACHING FOR M.C. • The drug that you have been taking is ephedrine. It is called an adrenergic agonist (or a sympathomimetic drug). Ephedrine acts by mimicking the effects of the sympathetic nervous system, which is the part of your nervous system that is responsible for your response to fear or danger (this is called the “fight-or-flight” response). Because this drug triggers many effects in the body, Skin: colour and temperature GI: abdominal examination GU: urine output, bladder percussion and prostate palpation Respiratory: respiratory rate and adventitious sounds Implementation Ensure safe and appropriate administration of the drug. Provide comfort and safety measures: temperature and lighting control (person may have pupil dilation secondary to sympathetic effects), mouth care and skin care. Monitor blood pressure, pulse rate and respiratory status throughout drug therapy. Provide support and reassurance to deal with drug therapy and effects. Provide teaching about drug name, dosage, side effects, precautions and warning signs to report. Evaluation Evaluate drug effects: relief of enuresis. Monitor for adverse effects: CV effects, dizziness, confusion, headache, rash, difficulty voiding, sweating, flushing and pupillary dilation. Monitor for drug–drug interactions as indicated. Evaluate the effectiveness of the teaching program as well as comfort and safety measures.

is used in many combination cold and allergy products. Parenterally it is used to treat shock or shock-like states, to overcome paroxysmal supraventricular tachycardia, to prolong local anaesthesia and to maintain blood pressure during spinal anaesthesia. Topically it is used to treat allergic rhinitis and to relieve the symptoms of otitis media. Ophthalmically it is used to dilate the pupils for eye examination, before surgery or to relieve elevated eye pressure associated with glaucoma. Phenylephrine is found in many cold and allergy products because it is so effective in constricting topical vessels and decreasing the swelling, signs and symptoms of rhinitis. Clonidine specifically stimulates central nervous system (CNS) a 2 -receptors. This leads to decreased symp­ athetic outflow from the CNS because the a 2 -receptors moderate the release of noradrenaline from the nerve axon. Clonidine is available in oral and transdermal you may experience some undesired adverse effects. It is crucial to discuss the effect of the drug with your healthcare provider and to try to make the effect as tolerable as possible. • If the drug is in a solution, check it before each use. If the solution is pink, brown or black, discard it. • If you have diagnosed prostate problems, it might help to void before taking each dose of the drug. • Some of the following adverse effects may occur: • Restlessness or shaking : If these occur, avoid driving, operating machinery or performing delicate tasks. • Flushing or sweating : Avoid warm temperatures and heavy clothing; frequent washing with cool water may help. • Heart palpitations : If you feel that your heart is beating too fast or skipping beats, sit down for a while and rest. If the feeling becomes too uncomfortable, notify your healthcare provider. • Sensitivity to light : Avoid glaring lights or wear sunglasses if you are in bright light. Be careful when moving between extremes of light because your vision may not adjust quickly. • Report any of the following to your healthcare provider: difficulty voiding, chest pain, difficulty breathing, dizziness, headache or changes in vision. • Do not stop taking this drug suddenly; make sure that you have enough of your prescription. This drug dose should be reduced gradually over 2 to 4 days when you are instructed to discontinue it by your healthcare provider. • Avoid OTC medications, including cold and allergy remedies and diet pills. If you feel that you need one of these, check with your healthcare provider first. • Tell any healthcare provider who takes care of you that you are taking this drug. • Keep this drug and all medications out of the reach of children. Do not share this drug with other people.