Summary
Isuprel is a medication that is applicable in treatment of mainly cardiovascular disorders such as heart block, cardiac arrest, bradycardia, ventricular fibrillation, and torsades de pointes, and respiratory disorders like asthma, bronchitis, and emphysema.
In pharmacodynamics, Isuprel is a beta-adrenergic agonist, which stimulates heartbeat and causes relaxation of smooth muscles. Pharmacokinetics shows that the body easily absorbs Isuprel in blood after an injection, experiences stimulation of beta-adrenergic receptors, metabolizes it using catechol-o-methyl transferase, and excretes via the kidneys. Since Isuprel has serious adverse effects on the functioning of the heart, healthcare providers should be cautious when administering to patients by considering their interactions with adrenaline, anesthetics, antidepressants, and beta-adrenergic blocking agents. Routine monitoring of heartbeat, electrolytes, and acid-base balance is central in forestalling serious adverse effects.
Introduction
Isuprel, also called Isoproterenol or isoprenaline, is a medication that is applicable in treatment of cardiovascular and respiratory disorders. Isuprel is mainly applicable in the treatment of cardiovascular disorders like bradycardia, cardiac arrest, ventricular fibrillation, and torsades de pointes (Mosby, 2011). Isuprel can also treat respiratory disorders like bronchitis, asthma, and emphysema. The common trade names are medihaler-Iso and Isuprel.
Its generic name is Isoproterenol hydrochloride, which exists in the form of solution and administered through injection. Isuprel is a beta-adrenergic agonist in that its mechanism of action is similar to that of the adrenaline, which increases the rate of heartbeat. Owing to some allergic reactions that Isuprel causes, its administration requires great caution. Therefore, given the medical importance of Isuprel, this drug report examines its description, uses, pharmacodynamics, administration and dosage, pharmacokinetics, adverse effects, precautions, and drug interactions.
Isuprel
Description
Isuprel is a trade name of the drug called Isoproterenol hydrochloride. According to Daily Med (2014), Isuprel is a synthetic sympathomimetic amine with a structure that resembles that of the epinephrine with a molecular weight of 247.72 and molecular formula of C11H17NO3-HCL. The resemblance makes Isuprel have the same mechanism of action as epinephrine. In essence, Isuprel is a beta-adrenergic agonist, which induces relaxation of smooth muscles, enhances heartbeat, and improves blood pressure. The solution of Isuprel contains Isoproterenol, lactic acid, sodium lactate, sodium chloride, and sodium metabisulfite with acidic pH that range from 2.5 to 4.5. Since the solution of Isuprel is nonpyrogenic, subcutaneous, intramuscular, and intravenous are possible routes of administration.
Uses
Isuprel is a drug that is applicable in treating cardiovascular disorders such as heart block, bradycardia, cardiac arrest, ventricular fibrillation, and torsades de pointes. Since Isuprel is a beta-adrenergic agonist, Mullins (2008) states that it increases ventricular rate and accelerate artrioventricular node. Through its accelerating mechanism, Isuprel increases the rate of heartbeat among patients with bradycardia and other cardiac disorders, which slowdown the rate of heartbeat. In enhancing the functioning of the cardiovascular system, Isuprel reduces peripheral resistance and consequently stimulates positive chronotropic, inotropic, and dromotropic effects.
Moreover, Isuprel is applicable in treatment of respiratory disorders such as asthma, bronchitis, and emphysema. As Isuprel is a bronchodilator, it relaxes respiratory muscles and reliefs breathing difficulties associated with disorders such as asthma, bronchitis, and emphysema. Fundamentally, the action of Isuprel as beta-adrenergic agonist makes it an important medication in increasing the rate of heartbeat and inducing the relaxation of smooth muscles in blood vessels and lungs.
Administration and Dosage
The common route of administering Isuprel is intravenous by infusion because it is a nonpyrogenic drug and has favorable pharmacodynamics and pharmacokinetics. However, in cases of emergencies, which require immediate therapeutic effect, intracardiac injection is appropriate. Since the dosage of the drug varies according to the severity of the condition, Hospira recommends its administration at increasing concentrations and in response to prognosis. According to Mullins (2008), the recommended dose is “0.05-.02 mcg/kg/min infused intravenously and repeated at the increasing dose for effect up to 1 mcg/kg/min” (p. 53). The ability of the cardiac pacemaker to sustain the rate of heartbeat determines route of administration and the dosage of Isuprel.
Pharmacodynamics
The pharmacodynamics of Isuprel makes it an important drug for the treatment of cardiovascular and respiratory disorders. Mosby (2011) states that Isuprel is a beta-adrenergic agonist, which acts by stimulating beta-adrenergic receptors and enhances cardiac output, stroke volume, and myocardial contractility. The stimulating effects of Isuprel improve functioning of the heart, particularly in instances of slow heart rate or bradycardia.
Daily Med (2014) holds that stimulation of beta-adrenergic receptors induces positive chronotropic, inotropic, and dromotropic effects on cardiac muscles. Additionally, Isuprel causes relaxation of smooth muscles in the blood vessels, and thus, reduces peripheral resistance of blood flow. In the treatment of respiratory disorders, Isuprel causes relaxation of smooth muscles of the lungs and alleviate breathing difficulties associated with diseases such as asthma, bronchitis, and emphysema. Mullins (2008) explains that Isuprel is a pulmonary vasodilator as it induces bronchial relaxation of smooth muscles. The ability of Isuprel to relax the smooth muscles of the lungs has made it effective in the treatment of respiratory disorders.
Pharmacokinetics
Pharmacokinetics entails a sequential process of liberation, absorption, distribution, metabolism, and excretion of drugs in the body. Parenteral routes are appropriate in administering Isuprel in that intravenous route is the common method of infusion, intracardiac route is applicable during emergencies, and subcutaneous and intramuscular routes offer alternative parenteral routes (Medsafe, 2014).
The blood then liberates Isoprenaline from the Isuprel and absorbs it into the cells, where it interacts with beta-adrenergic receptors. According to Medsafe, (2014), Isuprel distributes to various parts of the body within the half-life of 2 hours before undergoing metabolism by catechol-o-methyl transferase in the liver. 3-Methylisoprenaline is a major metabolite of Isuprel following parenteral administration (Mosby, 2011). Eventually, the metabolites of Isuprel undergo excretion via the kidneys.
Adverse Effects
The use of Isuprel has some adverse reactions that vary from one patient to another. Daily Med (2014) identifies headache, nervousness, dizziness, nausea, and visual blurring as some of the adverse effects of Isuprel on the central nervous system.
Moreover, Mullins (2008) states that Isuprel has adverse effects on cardiovascular system because it causes angina, palpitations, tachycardia, tachyarrhythmias, ventricular arrhythmias, and pulmonary edema amongst others. In the respiratory system, Isuprel causes dypnea, while other general effects are mild tremors, pallor, flashes, fatigue, and sweats. Overdose of Isuprel causes aforementioned side effects in addition to decreased blood pressure, focal myocarditis, and cardiac enlargement. In this view, healthcare providers should carefully monitor the progress of patients during administration of Isuprel to avert adverse effects and stabilize their conditions.
General Precautions
- As a means of preventing adverse effects, the dosage of Isuprel should commence at the lowest recommended concentration and increase gradually up to the highest effective concentration, which is dependent on the response and the progress of a patient. Daily Med (2014) states that doses that cause the rate of heartbeat to be over 130 beats per minute have adverse effects on the heart because they overwork the heart, increase oxygen demand, and induce ventricular arrhythmias.
- Healthcare providers should take necessary caution when administering Isuprel to patients with diabetes, coronary insufficiency, hyperthyroidism, and coronary heart disease since they are prone to side effects (Daily Med, 2014).
- Before administering vasoactive drugs like Isuprel, sufficient replacement of the intravascular volume is essential to avert avoidable adverse effects owing to abuse of the drug (Daily Med, 2014).
- Regular monitoring of patients is necessary to avert adverse effects, which occur due to overdose or therapeutic effects. Medsafe (2014) recommends regular assessment of blood pressure, the rate of heartbeat, and the flow of urine as effective parameters of monitoring the response of patients following the administration of Isuprel. Essentially, the rate of heartbeat should not exceed 110 beats per minute and electrolyte and acid-base balance should be below normal levels.
Drug Interactions
Since adrenaline and Isuprel are vasoactive drugs and beta-adrenergic agonists, healthcare providers should not administer them at once because they would cause severe arrhythmias (Medsafe, 2014). Moreover, extra caution is necessary if patients use anesthetics such as cyclopropane and halothane, and antidepressants. The use of beta-adrenergic blocking agents is not appropriate because it antagonizes the functioning of Isuprel. Combined use of the central nervous system stimulants and Isuprel increases the occurrence of adverse effects.
Conclusion
Isuprel is a medication used in the treatment of cardiovascular disorders and respiratory disorders. It is a beta-adrenergic agonist, which acts by stimulating beta-adrenergic receptors and causing increased heartbeat and enhanced relaxation of smooth muscles in the bronchi and blood vessels. The mechanism of action of Isuprel is similar to that of adrenaline because they are both beta-adrenergic agonists.
Parenteral routes of administration are appropriate because they offer optimum pharmacokinetics and pharmacodynamics mechanisms. Owing to the side effects, healthcare providers should consider drug interactions with adrenaline, antidepressants, and anesthetics, and keenly monitor progress of patients during infusion. Routine assessment of heartbeat, electrolytes, and acid-base balance is essential in monitoring the adverse effects of Isuprel.
References
Daily Med: Isuprel (Isoproterenol hydrochloride) injection, solution. (2014). Web.
Medsafe: Isuprel. (2014). Web.
Mosby, C. (2011). Mosby’s drug reference for health professions. New York: Elsevier Health Sciences.
Mullins, C. (2008). Cardiac Catheterization in Congenital Heart Disease: Pediatric and Adult. London: John Wiley & Sons.