Beta-2 Adrenergic Agonist (Injection, Oral)

Beta-2 adrenergic agonists, such as epinephrine, albuterol and metaproterenol, are a group of drugs which stimulate nerves in various parts of the body, most commonly to relieve breathing difficulties and treat severe allergic reaction.

Overview

Beta-2 adrenergic agonists are a group of drugs known as bronchodilators which work to stimulate nerves in different parts of the body. They are most commonly used to widen the airways of the lungs, known as the bronchial passages, to ease coughing, wheezing, troubled breathing and shortness of breath. These symptoms are all associated with conditions which affect the lungs, such as asthma, bronchitis and emphysema.

One particular type of beta-2 adrenergic agonist epinephrine is used as an emergency treatment for allergic reactions. It works to open up the airways and reduce wheezing, as well as to relieve swelling of the nose, lips, tongue and eyes and reduce itching, skin rashes and hives. Allergic reactions of this nature may have been caused by insect stings, foods, medicines or other substances.

Sometimes beta-2 adrenergic agonists are used to treat other conditions as determined by a medical professional.

The following are examples of beta-2 adrenergic agonists:

  • Albuterol (inhaler, solution, syrup, tablets): treats and prevents bronchospasm (sudden constriction of muscles in airways of lungs)
  • Ephedrine (capsules, tablets): relieves shortness of breath, wheezing and chest tightness associated with bronchial asthma
  • Epinephrine (injection): relaxes muscles and tightens airways for emergency treatment of allergic reaction
  • Isoproterenol (injection): treats mild heart block, cardiac arrest (until better treatments are available), bronchospasm which occurs during anesthesia, and hypovolemic shock, septic shock, low cardiac output, congestive heart failure and cardiogenic shock (only as part of other treatments or procedures)
  • Metaproterenol (tablets): opens airways to reduce breathing problems that may be caused by spasms associated with lung diseases
  • Terbutaline (injection): opens airways to reduce breathing problems that may be caused by spasms associated with lung diseases

There are several different dosage forms of beta-2 adrenergic agonists, including:

  • Solution
  • Injectable
  • Tablet
  • Syrup
  • Capsules

Most of them require a doctor's prescription, except for ephedrine which is often an ingredient in over-the-counter medicines such as cold and flu relief. However, it is recommended to check with a doctor before buying and using medicines that contain ephedrine.

In the US, beta-2 adrenergic agonists are sold under the following brand names:

  • Alupent
  • Brethine
  • Proventil
  • Proventil Repetabs
  • Ventolin
  • Volmax
  • VoSpire ER

Condition(s) treated?

  • Broncal asthma
  • Bronchitis
  • Chronic obstructive pulmonary disease (COPD)
  • Emphysema
  • Allergic reaction

Type of medicine?

  • Bronchodilator
  • Adrenaline

Side Effects

In rare instances, beta-2 adrenergic agonists can cause allergic reaction. If an allergic reaction is suspected, seek emergency medical care. Symptoms of allergic reaction include:

  • Tightness in throat
  • Trouble swallowing or breathing
  • Hive-like swellings on face, eyes, lips, tongue, throat, hands, feet or genitals
  • Hoarseness

Although rare, severe reactions have been reported in children taking albuterol by mouth. If any of the following symptoms occur in children taking this medicine, seek emergency medical care:

  • Chest pain
  • Chills
  • Fever
  • Sore throat
  • General feeling of illness or being unwell
  • Cramps or pain in muscles
  • Nausea
  • Vomiting
  • Painful eyes
  • Irritated or red eyes
  • Bleeding or crusty sores on lips
  • Sores, ulcers or white spots on lips or in mouth
  • Rash, sores or hives on skin or itchy skin

In all ages, more common side effects of beta-2 adrenergic agonists are fast heartbeat and irregular heartbeat. If you experience these symptoms, report them to your doctor as soon as possible. You should also tell your doctor about the following side effects, which are relatively rare:

  • Chest pain
  • Convulsions or seizures
  • Cramps or pain in muscles
  • Fainting (usually associated with isoproterenol)
  • Hives
  • Sudden increase in blood pressure (usually associated with ephedrine and epinephrine)
  • Mental problems such as poor memory or confusion
  • Nausea or vomiting
  • Difficulty urinating
  • Abnormal weakness or fatigue

Some side effects associated with beta-2 adrenergic agonists are less serious and don't necessarily need medical attention. In some instances, they may occur only temporarily as your body adjusts to the medicine, but if you find them to be persistent and they're affecting your quality of life, discuss them with your doctor. They may be able to prescribe an alternative treatment or give you advice on lifestyle changes you could make to reduce or prevent the side effects.

The most common minor side effects of beta-2 adrenergic agonists are:

  • Anxiety (mainly associated with epinephrine)
  • Nervousness
  • Headache
  • Tremors (mild shaking or quivering)

Less common minor side effects include:

  • Dizziness
  • Feeling as though self or surroundings are constantly moving
  • Sweating
  • Trouble sleeping

Not all of the side effects listed here have been reported for every type of beta-2 adrenergic agonist, but they have been reported for at least one. Since all drugs in this class are similar, there is always a risk that they could occur for all of them. If you notice any other side effects not listed here, consult your doctor urgently. You could also report them to the FDA.

Dosage

Dosages of beta-2 adrenergic agonists vary depending on the type of medicine, the medical conditions being treated and a range of other factors, such as your age and medical history. The dosages described below are averages. Always follow your doctor's prescribed dosages and their instructions in regard to the frequency at which doses should be taken, and the length of time treatment is needed for.

Albuterol dosing

Solution and syrup oral dosage forms

  • Adults and children aged 12+: 2 to 4 mg three or four times daily
  • Children aged 6 to 12: 2 mg three or four times daily
  • Children aged 2 to 6: between 0.1 mg and 2 mg three or four times daily depending on patient's weight (usually 0.045 mg per pound)
  • Children under 2: use and dose determined by doctor

Tablets oral dosage form

  • Adults and children aged 14+: 2 to 4 mg three or four times daily
  • Children aged 6 to 12: 2 mg three or four times daily
  • Children under 6: use and dose determined by doctor

Injection dosage form

  • Doses are established based on the weight of the patient and should be determined by a doctor. Injections are administered either into a muscle, or slowly into a vein over a long period.

Ephedrine Dosing

Ephedrine is sometimes an ingredient in cold and flu medicines which are sold over-the-counter. These may be in tablet, capsule, syrup, solution or elixir forms. Dosing may vary from brand to brand; always read the instructions on the medicine packaging and never consume more than the recommended dose or take doses more frequently than recommended. If in doubt about dosing instructions, consult a doctor or pharmacist.

Epinephrine dosing

Injection dosage form for allergic reactions

  • Adults: 0.3 to 0.6 mg, injected into muscle or under skin initially, followed by up to two more doses if necessary, each spaced 10 to 20 minutes apart. 0.1 to 0.25 mg may be injected slowly into a vein by a doctor if necessary.
  • Children: dose depends on body weight with average being 0.045 mg per pound, up to 0.3 mg maximum dose, injected into muscle or under skin, followed by up to two more doses if necessary, each spaced 15 minutes apart.

Injection dosage for bronchial asthma, chronic bronchitis or other lung disease

  • Adults and children: dose depends on body weight with average being 0.045 mg per pound, up to 0.5 mg maximum dose, injected under the skin, followed by up to two more doses if necessary, each spaced 20 minutes apart.
  • Children: dose depends on body weight with average being 0.045 mg per pound, up to 0.3 mg maximum dose, injected under the skin, followed by up to three more doses if necessary, each spaced 15 minutes apart.

Metaproterenol dosing

Syrup or tablets oral dosage forms

  • Adults and children aged 9+ and weighing more than 59 pounds: 20 mg, three or four times daily
  • Children aged 6 to 9 weighing less than 59 pounds: 10 mg, three or four times daily
  • Children under 6: use and dose determined by doctor

Terbutaline dosing

Tablets oral dosage form

  • Adults and teens aged 15+: 5 mg, taken every 6 hours while awake and up to three times daily
  • Children aged 12 to 15: 2.5 mg, taken every 6 hours while awake and up to three times daily
  • Children under 6: use and dose determined by doctor

Injection dosage form

  • Adults and children 12+: 2.5 mg, injected under the skin and repeated once if necessary after 15 to 30 minutes, with no more than 5 mg taken within a four-hour period
  • Children aged 6 to 12: dose dependent on body weight with average being 0.23 to 0.45 mg per pound, injected under the skin and repeated up to two more times ever 15 to 20 minutes
  • Children under 6: use and dose determined by the doctor.

Isoproterenol dosing

Isoproterenol is administered by intravenous injection in a doctor's office or hospital setting, with the dosage determined by a doctor.

How to take beta-2 adrenergic agonists

If taking tablets or capsules, do not crush, chew or break them; swallow them whole with water.

If using epinephrine injections, check with your healthcare provider on how to safely administer the medicine. It's important that you know how to administer the injections so that you can act quickly in emergency situations. The medicine is designed to be injected into the muscle, and the thigh is the best place for this. Do not inject it into the buttocks.

Epinephrine injections should be administered as soon as signs of severe allergic reaction occur. Then, the patient should go to the nearest hospital emergency room or immediately notify their doctor for follow-up treatment. Always let your doctor know if you have had to use the epinephrine injection, even if you have subsequently received care at a hospital or by another medical professional. If the allergic reaction was caused by an insect sting, remove the stinger as soon as possible. Use tweezers or your fingernails to avoid pinching or squeezing the stinger or pushing it deeper into the skin. You can then apply ice to the stung area to relieve pain and inflammation.

If using an auto-injector, do not remove the device's safety cap until you are ready to use it; doing so could activate the device during handling or storage. To use it, remove the safety cap, place the tip of the device against the thigh at a 90-degree angle, then press it hard into the thigh until the auto-injector functions. Hold it in place for several seconds before discarding. Massage the injection site for 10 seconds.

Epinephrine injections should be kept with you at all times in order that they can be administered as soon as severe allergic reaction occurs. You should also have your doctor's contact details and details of your nearest emergency room readily available. Check the expiry date of the medicine regularly and replace it before it reaches its expiry date. If the solution or suspension becomes brownish or pinkish in color or cloudy, do not use it and replace it as soon as possible.

Interactions

Make sure your doctor is aware of all medicines you are currently taking before beta-2 adrenergic agonists are administered to you. This is to avoid harmful drug interactions which could make your medical problems worse, increase the risk of side effects or cause other complications. You should take particular care to notify your doctor if you're taking any of the medicines listed below. However, this list may not be exhaustive, so it is usually safer to simply list all medicines you're using, including those prescribed and those purchased over-the-counter, to your doctor.

The following medicines are not recommended for concurrent use with beta-2 adrenergic agonists. If you are already taking any of them, your doctor may choose not to treat you with beta-2 adrenergic agonists or they may change the medicines you're already taking:

  • Amifampridine
  • Amisulpride
  • Bepridil
  • Cisapride
  • Dronedarone
  • Fluconazole
  • Ketoconazole
  • Mesoridazine
  • Nelfinavir
  • Pimozide
  • Piperaquine
  • Posaconazole
  • Saquinavir
  • Sparfloxacin
  • Terfenadine
  • Thioridazine
  • Ziprasidone

The following medicines are not recommended for concurrent use with beta-2 adrenergic agonists, but they may be required in some instances. If both medicines are deemed absolutely necessary, your doctor may adjust the dosages of the medicines or the way you take them. For example, they may instruct you to take the medicines at different times of day, or less frequently than usual. Always follow your doctor's instructions.

  • Albuterol
  • Alfuzosin
  • Amineptine
  • Amiodarone
  • Amitriptyline
  • Amitriptylinoxide
  • Amoxapine
  • Amprenavir
  • Anagrelide
  • Apomorphine
  • Aripiprazole
  • Arsenic Trioxide
  • Asenapine
  • Astemizole
  • Atazanavir
  • Atomoxetine
  • Azithromycin
  • Boceprevir
  • Buserelin
  • Butriptyline
  • Ceritinib
  • Chloroquine
  • Chlorpromazine
  • Ciprofloxacin
  • Citalopram
  • Clarithromycin
  • Clomipramine
  • Clozapine
  • Cobicistat
  • Conivaptan
  • Crizotinib
  • Dabrafenib
  • Darunavir
  • Dasabuvir
  • Dasatinib
  • Degarelix
  • Delamanid
  • Desipramine
  • Deslorelin
  • Dibenzepin
  • Disopyramide
  • Dofetilide
  • Dolasetron
  • Domperidone
  • Donepezil
  • Dothiepin
  • Doxepin
  • Droperidol
  • Efavirenz
  • Entacapone
  • Epinephrine
  • Escitalopram
  • Fenoterol
  • Fingolimod
  • Flecainide
  • Fluoxetine
  • Fosamprenavir
  • Gatifloxacin
  • Gemifloxacin
  • Gonadorelin
  • Goserelin
  • Granisetron
  • Halofantrine
  • Haloperidol
  • Hexoprenaline
  • Histrelin
  • Hydroxychloroquine
  • Hydroxyzine
  • Ibutilide
  • Idelalisib
  • Iloperidone
  • Imipramine
  • Indinavir
  • Iobenguane I 123
  • Iprindole
  • Itraconazole
  • Ivabradine
  • Ketoconazole
  • Lapatinib
  • Leuprolide
  • Levalbuterol
  • Levofloxacin
  • Lofepramine
  • Lopinavir
  • Lumefantrine
  • Mefloquine
  • Melitracen
  • Methadone
  • Metronidazole
  • Mifepristone
  • Nafarelin
  • Nefazodone
  • Nelfinavir
  • Nilotinib
  • Norfloxacin
  • Nortriptyline
  • Octreotide
  • Ofloxacin
  • Ombitasvir
  • Ondansetron
  • Opipramol
  • Paliperidone
  • Panobinostat
  • Paritaprevir
  • Pasireotide
  • Perflutren Lipid Microsphere
  • Pimavanserin
  • Pitolisant
  • Procainamide
  • Prochlorperazine
  • Promethazine
  • Propafenone
  • Propizepine
  • Protriptyline
  • Quetiapine
  • Quinidine
  • Quinine
  • Ranolazine
  • Ritonavir
  • Saquinavir
  • Sodium Phosphate
  • Sodium Phosphate, Dibasic
  • Sodium Phosphate, Monobasic
  • Solifenacin
  • Sorafenib
  • Sotalol
  • Sulpiride
  • Sunitinib
  • Tacrolimus
  • Telaprevir
  • Telavancin
  • Telithromycin
  • Tetrabenazine
  • Tianeptine
  • Tipranavir
  • Toremifene
  • Trazodone
  • Trifluoperazine
  • Trimipramine
  • Triptorelin
  • Troleandomycin
  • Tulobuterol
  • Vardenafil
  • Vemurafenib
  • Vinflunine
  • Voriconazole
  • Zuclopenthixol

Grapefruit juice may affect the way that beta-2 adrenergic agonists work in the body. Ask your doctor whether it's safe to consume grapefruit juice while taking your medicine.

Interactions with other medical conditions

Beta-2 adrenergic agonists may cause certain medical problems to get worse, or the presence of some medical problems could increase the risk or worsen side effects associated with these medicines. Make sure your doctor knows about all of your pre-existing medical conditions. They may choose not to treat you with beta-2 adrenergic agonists, or they may adjust the dosages to minimize the risk of complications. They may also explain risks of complications with you and tell you of specific side effects or symptoms to look out for which might be caused by the interaction.

In people with a history of convulsions or seizures, beta-2 adrenergic agonists may make the condition worse. They could also worsen heart rhythm problems in those with a history of abnormal heartbeats. These types of drugs are also known to increase blood sugar, which might cause problems for people with type 2 diabetes. Insulin or diabetes medicine doses may be adjusted to compensate.

In people with Parkinson's disease, epinephrine may make trembling and or stiffness worse. Epinephrine could also worsen symptoms in patients with psychiatric problems, and it can also exacerbate enlarged prostate in men with this condition.

In people with high blood pressure or overactive thyroid, ephedrine and epinephrine can both cause extremely high blood pressure. The risk of other side effects may also increase.

The extended-release form of albuterol could result in intestinal blockages in patients with gastrointestinal narrowing.

Warnings

Pediatric use

Infants and children may be very sensitive to the effects of epinephrine. Doctors may administer lower doses to minimize harm.

Children aged between 2 and 6 years old are more likely to experience nervousness or excitement after taking albuterol than adults and older children.

Elderly patients

Older adults may be more sensitive to beta-2 adrenergic agonists than younger adults. They are more likely to experience high blood pressure, trembling, or fast or irregular heartbeats.

Use during pregnancy

Some beta-2 adrenergic agonists may increase blood pressure, heart rate and blood sugar in pregnant women, and in the fetus they may also cause elevated heart rate and reduced blood sugar. If you are taking any beta-2 adrenergic agonists and you become pregnant, tell your doctor straight away.

It is also known that beta-2 adrenergic agonists can relax uterine muscles and subsequently delay labor. In the past, terbutaline injections have been used off-label to prevent or treat preterm labor. However, in 2011 the FDA issued a warning against this use of the drug, particularly for longer than 48 hours. This is because it can cause life-threatening maternal heart problems. In some instances, doctors may administer the drug for this purpose if they deem it absolutely necessary, but the FDA advises that this should only take place in hospital settings and treatment should not be prolonged for more than 48 hours. It should never be used in home or outpatient settings.

In regard to the health of the fetus, some beta-2 adrenergic agonists may pose a risk of birth defects. Albuterol and metaproterenol have not been studied in pregnant women, but animal studies involving doses much higher than those administered to humans have resulted in fetal birth defects. Isoproterenol has not been studied in pregnant women, but there is evidence of birth defects occurring in animal studies. Ephedrine has not been studied in either pregnant women or animals, so it is therefore unknown whether it poses a risk of birth defects. Terbutaline does not appear to cause birth defects in humans, and in animal studies it did not cause birth defects even when administered at doses much higher than those given to humans. Finally, epinephrine has caused birth defects in humans, but since the drug can save lives in emergency situations, it may still be administered to pregnant women experiencing life-threatening allergic reaction.

Use of beta-2 adrenergic agonists while breastfeeding

Both ephedrine and epinephrine are excreted in human breast milk and they may cause unwanted side effects in nursing babies. Mothers are advised to avoid breastfeeding during treatment with these drugs.

Terbutaline is also excreted into breast milk, but so far there is no evidence to suggest that the drug poses harmful effects to nursing infants. Mothers should discuss potential risks with their doctor if they plan to breastfeed during terbutaline therapy.

It is not known whether albuterol, isoproterenol and metaproterenol are excreted in human breast milk. However, most medicines do pass into breast milk in small amounts, and it is therefore assumed that these drugs can. It isn't known what effects they may have on nursing infants. Mothers should discuss the potential risks with their doctor if they plan to breastfeed while taking these medicines.

Risk in diabetic patients

Beta-2 adrenergic agonists can cause blood sugar levels to rise. In people with diabetes, this might mean that they need to adjust the amount of insulin or other diabetes medicine they take. Discuss this with your doctor if you are prescribed a beta-2 adrenergic agonist.

Changes in condition in asthmatic patients

Although beta-2 adrenergic agonists are often prescribed to treat the symptoms of asthma, you should look out for changes in your symptoms and report them to your doctor. For example, if you find that the medicine doesn't relieve asthma attacks, makes your breathing worse or you need to use your asthma inhaler more often than normal, check with your doctor straight away.

Reduced blood flow caused by epinephrine

Epinephrine reduces blood flow in the immediate area where it is injected. If injected into the same spot too often, it can cause tissue damage. If you notice symptoms of this, such as severe pain in the injection area, consult your doctor immediately.

Never inject epinephrine into the hands and feet, since there is already reduced blood flow in these areas. Doing so increases the risk of tissue damage. If you accidentally inject the medicine into your hands or feet, go to an emergency room or check with your doctor immediately.

Use of medicines which may contain ephedrine

Some over-the-counter medicines, particularly those designed to treat colds, flu and sinus problems, contain ephedrine. If you're already taking another beta-2 adrenergic agonists, consuming additional ephedrine may increase the risk of or the severity of side effects. Always consult your doctor before using over-the-counter medicines.

Storage

Beta-2 adrenergic agonists should be stored in closed containers at room temperature, away from moisture, heat or direct light. They should not be frozen. Avoid storing them in the bathroom as the heat and humidity may affect them.

Always keep beta-2 adrenergic agonists away from pets and children. Store them up and away from the ground so that they are not within easy reach.

Do not share beta-2 adrenergic agonists with other people, particularly those which have been prescribed to you by a doctor. They can interact with other medicines and health conditions and be extremely harmful.

If you have beta-2 adrenergic agonists that you no longer use, ask your healthcare provider how to dispose of them appropriately. Do not keep unused medicine or expired medicine.

Summary

Beta-2 adrenergic agonists are a class of drugs which stimulate nerves. They are most frequently used to treat the symptoms of conditions affecting the lungs, such as bronchial asthma, bronchitis and emphysema, because they can help to widen the airways of the lungs and make breathing easier. Albuterol, ephedrine, metaproterenol and terbutaline are all examples of beta-2 adrenergic agonists commonly used to treat lung conditions.

One type of beta-2 adrenergic agonist, called epinephrine, is used to treat severe allergic reactions by opening up the airways, reducing swelling and alleviate rashes, hives and itching. People with severe allergies to foods, medicines, insect stings and other substances may be prescribed epinephrine injections to carry with them at all times so that they can administer the drug in an emergency should they suddenly and severely react to the allergen in question.

Beta-2 adrenergic agonists are available in a wide variety of dosage forms, including tablets, syrups, injectables, solutions and inhalers. Common brand names for these drugs include Alupent, Brethine Proventil and Ventolin.

The most common side effects associated with beta-2 adrenergic agonists are anxiety and nervousness, tremors, and headache. These are usually minor and don't necessarily require medical treatment. Some people may also notice dizziness, sweating, sleep problems, and the sensation of oneself or one's surroundings constantly moving.

More serious side effects often associated with beta-2 adrenergic agonists are fast and irregular heartbeats. If you experience these while taking a beta-2 adrenergic agonist, consult your doctor as soon as possible. Individuals with a history of heart rhythm problems are at an increased risk of these side effects.

In rare instances, beta-2 adrenergic agonists can cause severe allergic reactions. Seek emergency care if you notice a sudden tightness in the throat, hoarseness or difficulty swallowing or breathing, or severe hive-like swellings on the face, lips, tongue, hands, feet or genitals. In children, severe reactions to beta-2 adrenergic agonist albuterol have been reported when the drug has been taken by mouth. Emergency care should be sought if a child experiences chest pain, fever, sore throat, muscle cramps, nausea or vomiting, red, painful or irritated eyes, bleeding or crusty lips, or sores, ulcers, rash or hives.

Dosages of beta-2 adrenergic agonists vary depending on the specific drug being taken, the illness or symptoms being treated, and various other factors such as the age, weight and medical history of the patient. Always follow the dosing instructions given by your doctor.

If taking a beta-2 adrenergic agonist in tablet or capsule form, always swallow the medicine whole without breaking, crushing or chewing it. If you're administering beta-2 adrenergic agonist injections yourself, follow the instructions of your healthcare provider carefully; subcutaneous injections go under the skin, while intramuscular injections go into the muscle and are best administered on the thigh.

Individuals who are prescribed epinephrine injections should have their medicine to hand at all times in case of allergic reaction, along with contact details of their doctor and their local emergency room. They should check the expiry date of the medicine regularly and replace it before it expires. Epinephrine should not be injected into the hands or feet. Once epinephrine has been administered, emergency medical care should be sought for followup care.

Some beta-2 adrenergic agonists may cause increased blood pressure, heart rate and blood sugar when used during pregnancy, which may lead to elevated heart rate and reduced blood sugar in the fetus. Some are also associated with fetal birth defects. Furthermore, the drugs can relax uterine muscles and delay labor. For these reasons, beta-2 adrenergic agonists should be used with caution during pregnancy. If you are pregnant or could become pregnant, discuss the potential risks of the medicine with your doctor as it may be safer to find alternative treatment options.

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Last Reviewed:
December 23, 2017
Last Updated:
April 11, 2018
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