Isoprenaline (
INNAn International Nonproprietary Name is the official non-proprietary or generic name given to a pharmaceutical substance, as designated by the World Health Organization...
) or
isoproterenol (
USANUnited States Adopted Names are unique nonproprietary names assigned to pharmaceuticals marketed in the United States. Each name is assigned by the USAN Council, which is co-sponsored by the American Medical Association , the United States Pharmacopeial Convention , and the American Pharmacists...
, trade names
Medihaler-Iso and
Isuprel) is a sympathomimetic beta adrenergic agonist
medicationA pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
.
It is structurally similar to
epinephrineEpinephrine is a hormone and neurotransmitter that participates in the "fight or flight" response of the sympathetic nervous system...
(adrenaline) but acts selectively on beta receptors, activating β
1 and β
2 receptors equally.
Its primary use is for
bradycardiaBradycardia , as applied to adult medicine, is defined as a resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min....
or
heart blockA heart block is a disease in the electrical system of the heart. This is opposed to coronary artery disease, which is disease of the blood vessels of the heart...
. By activating β
1-receptors on the heart, it induces positive
chronotropicChronotropic effects are those that change the heart rate.Chronotropic drugs may change the heart rate by affecting the nerves controlling the heart, or by changing the rhythm produced by the sinoatrial node...
,
dromotropicDerives from the Greek word "Dromos," meaning avenue or entranceway to a building. A dromotropic agent is one which affects the conduction velocity of the AV node, and subsequently the rate of electrical impulses in the heart....
, and inotropic effects.
It can be used as an inhaled
aerosolParticulates, alternatively referred to as particulate matter or fine particles, are tiny particles of solid or liquid suspended in a gas or liquid. In contrast, aerosol refers to particles and the gas together. Sources of particulate matter can be man made or natural...
to treat
asthmaAsthma is a predisposition to chronic inflammation of the lungs in which the airways are reversibly narrowed. Asthma affects 7% of the population of the United States, and 300 million worldwide...
, although this is currently a rare treatment.
Isoprenaline (
INNAn International Nonproprietary Name is the official non-proprietary or generic name given to a pharmaceutical substance, as designated by the World Health Organization...
) or
isoproterenol (
USANUnited States Adopted Names are unique nonproprietary names assigned to pharmaceuticals marketed in the United States. Each name is assigned by the USAN Council, which is co-sponsored by the American Medical Association , the United States Pharmacopeial Convention , and the American Pharmacists...
, trade names
Medihaler-Iso and
Isuprel) is a sympathomimetic beta adrenergic agonist
medicationA pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
.
It is structurally similar to
epinephrineEpinephrine is a hormone and neurotransmitter that participates in the "fight or flight" response of the sympathetic nervous system...
(adrenaline) but acts selectively on beta receptors, activating β
1 and β
2 receptors equally.
Uses
Its primary use is for
bradycardiaBradycardia , as applied to adult medicine, is defined as a resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min....
or
heart blockA heart block is a disease in the electrical system of the heart. This is opposed to coronary artery disease, which is disease of the blood vessels of the heart...
. By activating β
1-receptors on the heart, it induces positive
chronotropicChronotropic effects are those that change the heart rate.Chronotropic drugs may change the heart rate by affecting the nerves controlling the heart, or by changing the rhythm produced by the sinoatrial node...
,
dromotropicDerives from the Greek word "Dromos," meaning avenue or entranceway to a building. A dromotropic agent is one which affects the conduction velocity of the AV node, and subsequently the rate of electrical impulses in the heart....
, and inotropic effects.
It can be used as an inhaled
aerosolParticulates, alternatively referred to as particulate matter or fine particles, are tiny particles of solid or liquid suspended in a gas or liquid. In contrast, aerosol refers to particles and the gas together. Sources of particulate matter can be man made or natural...
to treat
asthmaAsthma is a predisposition to chronic inflammation of the lungs in which the airways are reversibly narrowed. Asthma affects 7% of the population of the United States, and 300 million worldwide...
, although this is currently a rare treatment. Although it activates all beta
adrenergic receptorThe adrenergic receptors are a class of G protein-coupled receptors that are targets of the catecholamines, especially noradrenaline and adrenaline ....
s, it works in a similar fashion to the more selective β
2-adrenergic agonists e.g.
salbutamolSalbutamol or albuterol is a short-acting β
2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease...
, by relaxing the airways to increase airflow.
It is also supplied in ampules under the brand name Isuprel for injection and in
sublingualSublingual, literally 'under the tongue', from Latin, refers to the pharmacological route of administration by which drugs diffuse into the blood through tissues under the tongue...
pill form for treatment of
asthmaAsthma is a predisposition to chronic inflammation of the lungs in which the airways are reversibly narrowed. Asthma affects 7% of the population of the United States, and 300 million worldwide...
, chronic
bronchitisAcute bronchitis is an inflammation of the large bronchi in the lungs that is usually caused by viruses or bacteria and may last several days or weeks. Characteristic symptoms include cough, sputum production, and shortness of breath and wheezing related to the obstruction of the inflamed airways...
and
emphysemaEmphysema is a lung disease, characterized by an abnormal, permanent enlargement of air spaces distal to the terminal bronchioles. The disease is coupled with the destruction of walls, but without obvious fibrosis...
.
Used with caution, it can also be used to treat
torsades de pointesTorsades de pointes, or simply torsades is a French term that literally means "twisting of the points." It was first described by Dessertenne in 1966 and refers to a specific variety of ventricular tachycardia that exhibits distinct characteristics on the electrocardiogram .- Presentation :The ECG...
by congenital defect, in conjunction with overdrive pacing and magnesium.
Adipose tissueIn histology, adipose tissue or body fat or just fat is loose connective tissue composed of adipocytes. Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of fat, although it also cushions and insulates the body...
also has β-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
mesotherapyMesotherapy is a non-surgical cosmetic medicine treatment. Mesotherapy employs multiple injections of pharmaceutical and homeopathic medications, plant extracts, vitamins, and other ingredients into the subcutaneous fat...
for body contouring and to help decrease fat. Two studies showed that it can cause a decrease in thigh size.
Pharmacology
Isoproterenol is a β
1- and β
2-adrenoceptor agonist which was commonly used to treat asthma before the more widespread use of
salbutamolSalbutamol or albuterol is a short-acting β
2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease...
, which has more selective effects on the airways. Its
route of administrationA route of administration in pharmacology and toxicology is the path by which a drug, fluid, poison, or other substance is brought into contact with the body....
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 β
1 receptors and β
2 receptors on skeletal muscle
arterioleAn arteriole is a small diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. Arterioles have thin muscular walls and are the primary site of vascular resistance...
s. 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 rateHeart rate is determined by the number of heartbeats per unit of time, typically expressed as beats per minute , it can vary with as the body's need for oxygen changes, such as during exercise or sleep. The measurement of heart rate is used by medical professionals to assist in the diagnosis and...
(
tachycardiaTachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heartrate...
), which predisposes patients to cardiac dysrhythmias.
Other side effects include: nervousness, insomnia, restlessness, and headaches.
Warnings and contraindications
Isoproterenol should not be administered to patients with
myocardial ischaemiaIschaemic or ischemic heart disease , or myocardial ischaemia, is a disease characterized by reduced blood supply to the heart muscle, usually due to coronary artery disease...
.