Isoproterenol

INTRODUCTION

Indications

Management of bronchospasm during anesthesia. Treatment of asthma or COPD. Management of bradycardia (IV only).

Action

Results in the accumulation of cyclic adenosine monophosphate (cAMP) at beta-adrenergic receptors. Produces bronchodilation. Inhibits the release of mediators of immediate hypersensitivity reactions from mast cells. Has additional significant beta (cardiac)–adrenergic action, which results in positive inotropic and chronotropic effects. Therapeutic Effects: Bronchodilation. Increased heart rate.

Adverse Reactions/Side Effects

CNS: nervousness, restlessness, tremor, headache, insomnia. CV: ARRHYTHMIAS, angina, hypertension, tachycardia. GI: nausea, vomiting, xerostomia. Endo: hyperglycemia. Misc: pink/red discoloration of saliva.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Assess heart rate, ECG, and heart sounds, especially during exercise (See Appendices G, H). Immediately report any rhythm disturbances or symptoms of increased arrhythmias, including palpitations, chest discomfort, shortness of breath, fainting, and fatigue/weakness.

• Assess pulmonary function at rest and during exercise (See Appendices I, J, K) to document effectiveness of medication in controlling bronchospasm.

• Assess blood pressure (BP) periodically and compare to normal values (See Appendix F). Report a sustained increase in BP (hypertension) to the physician.

• Monitor and report signs of CNS toxicity, including nervousness, restlessness, or tremor. Sustained or severe CNS signs may indicate overdose or excessive use of this drug.

• Be alert for signs of hyperglycemia, including confusion, drowsiness, flushed/dry skin, fruit-like breath odor, rapid/deep breathing, polyuria, loss of appetite, and unusual thirst. Patients with diabetes mellitus should check blood glucose levels frequently.

Interventions

• When implementing airway clearance techniques or respiratory muscle training, attempt to intervene when the airway is maximally bronchodilated. Drug effect is usually rapid (within 5 min) after inhalation, so chest physical therapy interventions can begin soon after drug administration.

• Because of the risk of cardiovascular stimulation, use extreme caution during aerobic exercise and endurance conditioning. Cardiovascular effects such as arrhythmias, angina pectoris, or increased BP occur more commonly with isoproterenol compared to other bronchodilators because isoproterenol stimulates beta-1 receptors of the heart as well as beta-2 receptors on the lungs.

Patient/Client-Related Instruction

• Advise patient not to exceed the recommended dose or frequency of inhalations. Contact physician immediately if bronchospasm is not relieved by medication or is accompanied by diaphoresis, dizziness, or other symptoms.

• Counsel patient on proper use of inhaler; observe use of this device whenever possible to ensure proper technique.

• Instruct patient and family/caregivers to report severe or prolonged headache, sleep loss, or GI problems (nausea, vomiting, dry mouth).

Pharmacokinetics

Absorption: Well absorbed following IM or SC administration; IV administration results ...