McKenna's Pharmacology for Nursing, 2e

710

P A R T 8  Drugs acting on the cardiovascular system

R.A. stabilised rapidly and was given IV fluids to dilute the drug effects and encourage excretion. His PVCs became less and less frequent, and he remained in normal sinus rhythm. R.A. should be questioned about how and when he takes his drug and any other drugs he might be taking. He should also be reminded that antihistamines should be avoided while on digoxin. Because he was self-medicating with antihistamines, it is possible that the toxicity that developed was a drug–drug interaction. He should be encouraged to try increased fluid intake, use a room humidifier and possibly use a non-steroidal anti-inflammatory drug for pain relief to get through the cold that he experienced. Before leaving, he should have drug information reviewed to increase its safe use. He should take the drug twice a day and not skip any doses. If he does miss a dose, he should not catch up doses, but should just resume the regular schedule. He should avoid antihistamines, as well as other antiarrhythmics, while on this drug. It is a good idea to keep a complete list of drugs being taken—including over-the-counter drugs and herbal remedies—so the healthcare provider can check and make sure that there is no potential reaction to be concerned about. He should also be reminded about the importance of regular medical follow-up, which will include an electrocardiogram and blood tests, to evaluate the effects of the drug on his body. While R.A. is within the healthcare system, it would be a good idea to do a full electrocardiogram and to get blood tests to measure his creatinine levels, as well as serum electrolytes, which have an effect on cardiac conduction. Assess the person’s health history for allergies to digoxin; for any heart block or prolonged QT intervals; history of atrial fibrillation, including onset of last episode; and drug history for use of antihistamines, drugs that could prolong the QT interval, other antiarrhythmics or tricyclic antidepressants. Focus the physical examination on the following areas: Cardiovascular: blood pressure, pulse, heart rhythm, perfusion Neurological (CNS): orientation, affect, reflexes Respiratory system: respiratory rate and character, adventitious sounds Laboratory tests: renal function tests, serum electrolytes, electrocardiogram Implementation Continually monitor cardiac rhythm when initiating or changing dose. Ensure that emergency life support equipment is readily available. CARE GUIDE FOR R.A.: DIGOXIN (ANTIARRHYTHMIC AGENTS) Assessment: History and examination

Establish safety precautions, including side rails, lighting and noise control, if CNS effects occur. Arrange for periodic monitoring of cardiac rhythm when the person is receiving long-term therapy . Provide comfort measures, including small, frequent meals to minimise nausea and vomiting; access to bathroom facilities; and environmental controls, such as temperature regulation, light control and decreased noise. Offer support and encouragement to help the person deal with the diagnosis and the drug regimen. Provide teaching regarding drug name, dosage, schedule of administration, measures to reduce adverse effects, other drugs to avoid, what to report, and the need for regular, periodic monitoring. Evaluation Monitor response to the drug (stabilisation of cardiac rhythm and output). Monitor for adverse effects (sedation, hypotension, cardiac arrhythmias, respiratory depression, CNS effects). Monitor for drug–drug interactions. Evaluate the effectiveness of the teaching plan (person can name drug, dosage, adverse effects to watch for, specific measures to avoid them, and the importance of continued follow-up). Monitor the effectiveness of comfort measures and compliance with the regimen. TEACHING FOR R.A. • An antiarrhythmic drug, such as digoxin, acts to stop the irregular rhythm in your heart, helping it to beat more regularly and therefore more efficiently. • When taking digoxin, you should remember to take it twice a day. If you miss a dose, do not make up the dose, just return to your regular schedule. Never take more than two doses in a day. • Do not take antihistamines while you are on this drug; this combination can increase the adverse effects and can be quite serious. There are other drugs that should be avoided; make sure you give your healthcare provider a complete list of the drugs that you are taking, including over-the-counter drugs and herbal remedies, so the safety of any combinations can be checked. • Some adverse effects that might occur include the following: • Headache : Medication may be available to help if this is a problem. • Dizziness, light-headedness : Avoid driving a car or operating dangerous machinery until you know how this drug will affect you. • Nausea, diarrhoea, flatulence : Small, frequent meals may help to alleviate these problems.