Beta-2 Agonists

- Sympathomimetics increase cyclic adenine monophosphate (cAMP) levels, which causes bronchodilation

Beta-2

- Beta-2 agonists cause a relaxation in the bronchial smooth muscles (bronchodilation)

- Histamine release is inhibited

- Ciliary motility is increased

- Triggers glycogenolysis and increased insulin

Epinephrine

- With acute bronchospasms in cases of anaphylaxis, epinephrine is given to promote bronchodilation and increased blood pressure

- Epinephrine is a nonselective agonist that affects alpha-1, beta-1, and beta-2 receptors

- For chronic bronchospasms associated with [[Chronic Obstructive Pulmonary Disease]] or chronic asthma, selective beta-2 adrenergic agonists are used to bronchodilate

- Given as an aerosol or tablet

Complications

Epinephrine symptoms reflect SNS involvement

- Sympathetic cardiac changes

- Tachycardia

- Palpitations

- Dysrhythmias

- Angina

- HTN

- Tremors

- Dizziness

Beta-2 Agonists

Most beta-2 agonists end with the suffix "-terol"

- Albuterol is the short-term prototype and salmeterol is the long-term prototype drug

- For long-term asthma treatment, beta-2 agonists are usually administered orally by inhalation, MDI, or nebulizer

- Inhalation dosing is lower than oral dosing and more constricted to the bronchial site

- Onset for inhalation is 1 minute and 5-30 minutes by nebulization

- The peak for inhalation and oral administration is 1 hour and a duration of 4 hours

Albuterol

- Albuterol is a short-acting (rescue) medication

- Can be inhaled or administered orally

- Albuterol is a selective beta-2 agonist used for bronchodilation

- Has a long duration of action

- High dosages or overuse of beta-2 agonists for asthma may cause some beta-1 responses (nervousness, tremors, and increased HR)

Salmeterol

- Salmeterol is a long-acting medication

- Administered orally

Complications

Side effects of beta-2 agonists may diminish after 1 week or longer

Overuse of medications may reverse intended effects

- Tremors

- Caused by beta-2 receptors in skeletal muscles

- Headaches

- Restlessness

- High HR/Palpitations

- Oral agents can cause tachycardia and angina by stimulating alpha-1 receptors

- Glycogenolysis/Increased insulin secretions

- Patients with diabetes mellitus need to monitor their serum glucose