Beta2-adrenergic receptor agonist
Encyclopedia
β2-adrenergic agonists, also known as β2-adrenergic receptor agonists, are a class of drugs
Medication
A 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 :...

 used to treat asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

 and other pulmonary
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

 disease states.

Uses

They act on the beta2-adrenergic receptor
Beta-2 adrenergic receptor
The beta-2 adrenergic receptor , also known as ADRB2, is a beta-adrenergic receptor, and also denotes the human gene encoding it.-Gene:The gene is intronless...

, thereby causing smooth muscle
Smooth muscle
Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...

 relaxation, resulting in dilation of bronchial passages
Bronchus
A bronchus is a passage of airway in the respiratory tract that conducts air into the lungs. The bronchus branches into smaller tubes, which in turn become bronchioles....

, vasodilation
Vasodilation
Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins. The process is essentially the opposite of vasoconstriction, or the narrowing of blood vessels. When...

 in muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 and liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

, relaxation of uterine
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...

 muscle, and release of insulin
Insulin
Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....

.

Findings indicate Beta-2 stimulants, especially when they are given by parenteral or oral route, can induce adverse effects:
  • tachycardia secondary to peripheral vasodilation and cardiac stimulation..Tachycardia can be accompanied by palpitations.
  • tremor, sweats, agitation.
  • more severe effects, pulmonary edema, myocardial ischemia, cardiac arrythmia, are exceptional.


Asthma aggravation has been observed in patients using large dose of beta-2 stimulants, but it is not known if it results from spontaneous course of the disease or adverse effect of the drugs. The excipients, in particular sulphite, could contribute to the adverse effects. The possible loss of the bronchodilator activity of beta-2-mimetic could be attenuated by glucocorticoid intake.

Side Effects

Side-effects such as insomnia
Insomnia
Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...

, anxiety
Anxiety
Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...

, and tremor
Tremor
A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving to-and-fro movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, face, head, vocal folds, trunk, and legs. Most tremors occur in the...

 occur in some patients.

Delivery

All β2 agonists are available in inhaler
Inhaler
An inhaler or puffer is a medical device used for delivering medication into the body via the lungs. It is mainly used in the treatment of asthma and Chronic Obstructive Pulmonary Disease . Zanamivir , used to treat influenza, must be administered via inhaler...

 form, either metered-dose inhalers, which aerosol
Aerosol
Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...

ize the drug, or dry powder, which can be inhaled.

Salbutamol
Salbutamol
Salbutamol or albuterol is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It is marketed as Ventolin among other brand names....

 (known as albuterol in the U.S.) also comes in a solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...

 form for nebulization
Nebulizer
In medicine, a nebulizer is a device used to administer medication in the form of a mist inhaled into the lungs....

, which is more commonly used in inhalers than in emergency rooms
Emergency department
An emergency department , also known as accident & emergency , emergency room , emergency ward , or casualty department is a medical treatment facility specialising in acute care of patients who present without prior appointment, either by their own means or by ambulance...

. Salbutamol and terbutaline
Terbutaline
Terbutaline is a β2-adrenergic receptor agonist.Terbutaline is currently on the World Anti-Doping Agency's list of prohibited drugs for Olympic athletes, except when administered by inhalation and a Therapeutic Use Exemption has been obtained in advance.Terbutaline is currently used to delay...

 are also both available in oral forms. Nebuliser form is as effective as administering the drug intravenously.

In addition, several of these medications are available in intravenous
Intravenous therapy
Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein. The word intravenous simply means "within a vein". Therapies administered intravenously are often called specialty pharmaceuticals...

 forms, including both salbutamol
Salbutamol
Salbutamol or albuterol is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It is marketed as Ventolin among other brand names....

 and terbutaline
Terbutaline
Terbutaline is a β2-adrenergic receptor agonist.Terbutaline is currently on the World Anti-Doping Agency's list of prohibited drugs for Olympic athletes, except when administered by inhalation and a Therapeutic Use Exemption has been obtained in advance.Terbutaline is currently used to delay...

. It can be used in this form in severe cases of asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

, but it is more commonly used to suppress premature labor
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...

 because it also relaxes uterine muscle, thereby inhibiting contractions
Contraction (childbirth)
-Throughout menstrual cycle:The uterus frequently contracts throughout the entire menstrual cycle, and these contractions have been termed endometrial waves or contractile waves. These appear to involve only the sub-endometrial layer of the myometrium...

.

Risks

On November 18, 2005, Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

 (FDA) alerted healthcare professionals and patients that several long-acting bronchodilator
Bronchodilator
A bronchodilator is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lungs. Bronchodilators may be endogenous , or they may be medications administered for the treatment of breathing difficulties...

 medicines have been associated with possible increased risk of worsening wheezing
Wheeze
A wheeze is a continuous, coarse, whistling sound produced in the respiratory airways during breathing. For wheezes to occur, some part of the respiratory tree must be narrowed or obstructed, or airflow velocity within the respiratory tree must be heightened...

 in some people, and requested that manufacturers
Manufacturing
Manufacturing is the use of machines, tools and labor to produce goods for use or sale. The term may refer to a range of human activity, from handicraft to high tech, but is most commonly applied to industrial production, in which raw materials are transformed into finished goods on a large scale...

 update warnings
Precautionary statements
In United States safety standards, precautionary statements are sentences providing information on potential hazards, and proper procedures. They are used in situations from consumer product on labels and manuals, to descriptions of physical activities...

 in their existing product labeling.

On June 29, 2006, Cornell University
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...

 and Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...

 researchers reported that a meta-analysis
Meta-analysis
In statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...

 they conducted found that "regularly inhaled beta-agonists (Orciprenaline
Orciprenaline
Orciprenaline is a bronchodilator used in the treatment of asthma. Orciprenaline is a moderately selective beta2-adrenergic receptor agonist that stimulates receptors of the smooth muscle in the lungs, uterus, and vasculature supplying skeletal muscle, with minimal or no effect on...

/metaproterenol [Alupent], formoterol
Formoterol
Formoterol or eformoterol is a long-acting β2-agonist used in the management of asthma and/or chronic obstructive pulmonary disease...

 Foradil, Fluticasone/salmeterol
Fluticasone/salmeterol
The combination preparation fluticasone/salmeterol is a formulation containing fluticasone propionate and salmeterol xinafoate used in the management of asthma and chronic obstructive pulmonary disease...

 [Serevent, Advair], and Salbutamol
Salbutamol
Salbutamol or albuterol is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It is marketed as Ventolin among other brand names....

/albuterol [Proventil, Ventolin, Volmax, and others]) increased the risk of respiratory death more than twofold, compared with a placebo," while used to treat chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...

 (COPD).

On December 11, 2008, a panel of experts convened by the Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

 (FDA) voted to ban the drugs Serevent and Foradil from use in the treatment of asthma. It was shown that, when these two drugs are used without steroids, they increase the risks of more severe attacks. The experts said that two other much more popular asthma drugs containing long-acting beta-agonists, Advair and Symbicort, should continue to be used. The latter contains formoterol
Formoterol
Formoterol or eformoterol is a long-acting β2-agonist used in the management of asthma and/or chronic obstructive pulmonary disease...

 as contained in Foradil but also a steroid Budesonide
Budesonide
Budesonide is a glucocorticoid steroid for the treatment of asthma and non-infectious rhinitis , and for treatment and prevention of nasal polyposis...

.

Types

They can be divided into short-acting and long-acting beta-adrenoceptor agonist (LABA) groups:

Short-acting beta2 agonists

generic name (Trade Name)
  • salbutamol
    Salbutamol
    Salbutamol or albuterol is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It is marketed as Ventolin among other brand names....

      (albuterol (US name), Ventolin)
  • levosalbutamol (levalbuterol (US name), Xopenex)
  • terbutaline
    Terbutaline
    Terbutaline is a β2-adrenergic receptor agonist.Terbutaline is currently on the World Anti-Doping Agency's list of prohibited drugs for Olympic athletes, except when administered by inhalation and a Therapeutic Use Exemption has been obtained in advance.Terbutaline is currently used to delay...

      (Bricanyl)
  • pirbuterol
    Pirbuterol
    Pirbuterol is a beta-2 adrenergic bronchodilator used in the treatment of asthma, available as a breath-activated metered-dose inhaler .-Clinical use:...

      (Maxair)
  • procaterol
    Procaterol
    Procaterol, applied as procaterol hydrochloride , is a short-acting β2-adrenergic receptor agonist used for the treatment of asthma. It has never been filed for FDA evaluation in the United States, where it is not marketed. The drug is readily oxidated in the presence of moisture and air, making it...

  • metaproterenol (Alupent)
  • fenoterol
    Fenoterol
    Fenoterol is an asthma medication designed to open up the airways to the lungs. It is classed as sympathomimetic beta2 agonist.Fenoterol is produced and sold by Boehringer Ingelheim as Berotec N and in combination with ipratropium as Berodual N....

  • bitolterol mesylate
  • ritodrine
    Ritodrine
    Ritodrine is a tocolytic drug, was used to stop premature labor. It is available in oral tablets or as an injection, and is typically used as the hydrochloride salt, ritodrine hydrochloride...


Long-acting beta2 agonists

  • salmeterol
    Salmeterol
    Salmeterol is a long-acting beta2-adrenergic receptor agonist drug that is currently prescribed for the treatment of asthma and chronic obstructive pulmonary disease. It is currently available as a dry powder inhaler that releases a powdered form of the drug...

      (Serevent Diskus)
  • formoterol
    Formoterol
    Formoterol or eformoterol is a long-acting β2-agonist used in the management of asthma and/or chronic obstructive pulmonary disease...

      (Foradil, Symbicort)
  • bambuterol
    Bambuterol
    Bambuterol is a long acting beta-adrenoceptor agonist used in the treatment of asthma; it also is a prodrug of terbutaline. Commercially, the AstraZeneca pharmaceutical company produces and markets bambuterol as Bambec and Oxeol ....

  • clenbuterol
    Clenbuterol
    Clenbuterol is a sympathomimetic amine used by sufferers of breathing disorders as a decongestant and bronchodilator. People with chronic breathing disorders such as asthma use this as a bronchodilator to make breathing easier...


External links

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