McKenna's Pharmacology for Nursing, 2e

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P A R T 8  Drugs acting on the cardiovascular system

volume deficit, which could be made worse by increased renal perfusion ; and ventricular arrhythmias, which could be exacerbated by these drugs. Caution should be used in the elderly, who are more likely to develop adverse effects. There are no adequate studies about the effects of these drugs during pregnancy , and their use should be reserved for situations in which the benefit to the mother clearly outweighs the potential risk to the fetus. It is not known whether these drugs enter breast milk , so caution should be used if the woman is breastfeeding. Adverse effects The adverse effects most frequently seen with these drugs are ventricular arrhythmias (which can progress to fatal ventricular fibrillation), hypotension and chest pain. GI effects include nausea, vomiting, anorexia and abdominal pain. Thrombocytopenia can occur with milrinone. Hypersensitivity reactions associated with these drugs include vasculitis, pericarditis, pleuritis and ascites. Burning at the intravenous injection site is also a frequent adverse effect. Clinically important drug–drug interactions Precipitates form when these drugs are given in solution with frusemide. Avoid this combination in solution. Use alternative lines if both of these drugs are being given intravenously. vision”; unusual tiredness or weakness; skin rash or hives; swelling of the ankles, legs or fingers; difficulty breathing. • Tell any doctor, nurse, dentist or other healthcare provider that you are taking this drug. • Keep this drug, and all medications, out of the reach of children. • Avoid the use of over-the-counter medications while you are taking this drug. If you think that you need one of these, consult with your healthcare provider for the best choice. Many of these drugs contain ingredients that could interfere with your digoxin. • Consider wearing or carrying a medical identification to alert any medical personnel who might take care of you in an emergency that you are taking this drug. • Schedule regular medical checkups to evaluate the actions of the drug and to adjust the dose if necessary.

• Some of the following adverse effects may occur: • Dizziness, drowsiness, headache : Avoid driving or

P hosphodiesterase inhibitors The phosphodiesterase inhibitors (Table 44.1) belong to a second class of drugs that act as cardiotonic (inotropic) agents. These include milrinone ( Primacor ). Therapeutic actions and indications The phosphodiesterase inhibitors block the enzyme phosphodiesterase. This blocking effect leads to an increase in myocardial cell cyclic adenosine monophos­ phate (cAMP), which increases calcium levels in the cell (Figure 44.4). Increased cellular calcium causes a stronger contraction and prolongs the effects of sym­ pathetic stimulation, which can lead to vasodilation, increased oxygen consumption and arrhythmias. These drugs are indicated for the short-term treatment of HF that has not responded to digoxin or diuretics alone or that has had a poor response to digoxin, diuretics and vasodilators. See Table 44.1 for usual indications for each drug. Because these drugs have been associated with the development of potentially fatal ventricular arrhythmias, their use is limited to severe situations. Pharmacokinetics Milrinone is available only for intravenous use. It is widely distributed after injection, metabolised in the liver and excreted primarily in the urine. Contraindications and cautions Phosphodiesterase inhibitors are contraindicated in the presence of allergy to either of these drugs or to bisulfites. They also are contraindicated in the following condi­ tions: severe aortic or pulmonic valvular disease, which could be exacerbated by increased contraction ; acute MI, which could be exacerbated by increased oxygen consumption and increased force of contraction ; fluid performing hazardous tasks or delicate tasks that require concentration if these occur. Consult your healthcare provider for an appropriate analgesic if the headache is a problem. • Nausea, gastrointestinal upset, loss of appetite : Small, frequent meals may help; monitor your weight loss; if it becomes severe, consult your healthcare provider. • Vision changes, “yellow” halos around objects : These effects may pass with time. Take extra care in your activities for the first few days. If these reactions do not go away after 3 to 4 days, consult with your healthcare provider. • Report any of the following to your healthcare provider: unusually slow or irregular pulse; rapid weight gain; “yellow

Care considerations for people receiving phosphodiesterase inhibitors

Assessment: History and examination

■ ■ Assess for contraindications or cautions: any known allergies to these drugs or to bisulfites