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Isoprenaline (INN) or isoproterenol (USAN, trade names Medihaler-Iso and Isuprel) is a sympathomimetic beta adrenergic agonist medication.
It is structurally similar to epinephrine (adrenaline) but acts selectively on beta receptors, activating ß1 and ß2 receptors equally.[1]
Uses
Its primary use is for bradycardia or heart block. By activating ß1-receptors on the heart, it induces positive chronotropic, dromotropic, and inotropic effects.[1]
It can be used as an inhaled aerosol to treat asthma, although this is currently a rare treatment.[1] Although it activates all beta adrenergic receptors, it works in a similar fashion to the more selective beta2-adrenergic receptor agonists e.g. salbutamol, by relaxing the airways to increase airflow.
It is also supplied in ampules under the brand name Isuprel for injection and in sublingual pill form for treatment of asthma, chronic bronchitis and emphysema.
Used with caution, it can also be used to treat torsades de pointes, in conjunction with overdrive pacing and magnesium.
Adipose tissue also has ß-receptors that can be activated by isoproterenol. Once activated, adipocytes begin breaking down the fat stored inside them. This has caused isoproterenol to be used off-label in mesotherapy for body contouring and to help decrease fat. Two studies showed that it can cause a decrease in thigh size. [2]
Pharmacology
Isoproterenol is a ß1- and ß2-adrenoceptor agonist which was commonly used to treat asthma before the more widespread use of salbutamol, which has more selective effects on the airways. Its route of administration is either intravenous, oral, intranasal, subcutaneous, or intramuscular, depending on use. The plasma half-life for isoproterenol is approximately two hours.
Isoproterenol's effects on the cardiovascular system relate to its actions on cardiac ß1 receptors and ß2 receptors on skeletal muscle arterioles. Isoproterenol has positive inotropic and chronotropic effects on the heart. In skeletal muscle arterioles it produces vasodilatation. Its inotropic and chronotropic effects elevate systolic blood pressure, while its vasodilatory effects tend to lower diastolic blood pressure.
The adverse effects of isoproterenol are also related to the drug's cardiovascular effects. Isoproterenol can produce an elevated heart rate (tachycardia), which predisposes patients to cardiac dysrhythmias.
Other side effects include: nervousness, insomnia, restlessness, and headaches.[2]
Warnings and Contraindications
Isoproterenol should not be administered to patients with myocardial ischaemia.
References
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Adrenergic agonists (models/most important in small caps) |
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Nonselective ß
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ISOPRENALINE (ISOPROTERENOL)
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