Name of the B2 sympathomimetics Drugs
- Salbutamol
- Terbutaline
- Salmeterol
- Formoterol
- Bambuterol
Mechanism of Action of B2 sympathomimetics Drugs
Selective b2 adrenoceptor agonists in the smooth muscle of upper airways that increase intracellular cAMP. This leads to smooth muscle relaxation and bronchodilation
1.SALBUTAMOL
| Salbutamol |
| Availability: •inhaler 100 micrograms (mcg) per dose •dry powder inhaler 200 mcg per dose •oral syrup 2 mg/5 ml •tablets 2mg and 4mg •respirator solution 5 mg/ml – for use with nebulizer •injection 500 micrograms/ml •solution for infusion 5mg/5ml |
| Administration and handling : Salbutamol inhaler 100 micrograms (mcg) per dose: Adults: 1-2 puffs every 4 hours up to 4 times (8 puffs) in 24 hours to relieve symptoms. To prevent symptoms caused by exercise or other triggers, the recommended dose is 2 puffs 15 minutes before exposure. Children: 1 puff (increased to 2 puffs if required) every 4 hours up to 4 times (8 puffs) in 24 hours to relieve symptoms. To prevent symptoms caused by exercise or other triggers, the recommended dose is 1 puff (increased to 2 puffs if required) 15 minutes before exposure |
| Salbutamol dry powder inhaler 200 mcg per dose: Adults, adolescents aged 12 years and over and children 4 to 11 years of age: 1 inhalation up to 4 times per day to relieve symptoms. To prevent symptoms caused by exercise or other triggers, the recommended dose is 1 inhalation 10 to 15 minutes before exposure. |
| Salbutamol oral syrup 2 mg/5 ml: Adults (over 18 years old): The usual dose is 5 ml to 20 ml, up to 4 times a day. Children over 12 years old: The usual dose is 5 ml to 10 ml, 3 or 4 times a day. Children aged between 6 and 12 years: The usual dose is 5 ml, 3 or 4 times a day. Children aged between 2 and 6 years: The usual dose is 2.5 ml to 5 ml, 3 or 4 times a day. Elderly (over 65 years old): The usual dose is 5 ml, up to 3 times a day. |
| Salbutamol tablets 2mg and 4mg: Adults: The recommended dose is 4mg 3 or 4 times a day. Your doctor may increase this gradually up to a maximum of 8mg three or four times a day. Some patients may be treated successfully with 2mg three or four times a day. Children over 12 years old: The recommended dose is 2 mg to 4 mg 3 or 4 times a day. Children aged between 6 and 12 years: The recommended dose is 2 mg 3 or 4 times a day Children aged between 2 and 6 years: The recommended dose is 1 to 2 mg 3 or 4 times a day. Elderly or patients known to be sensitive to this product or other similar drugs: The recommended dose is initially 2 mg 3 or 4 times a day. |
| Salbutamol injection 500 micrograms/ml: Adults: The recommended dose for subcutaneous or intramuscular injection is 500 micrograms (8 micrograms/kg bodyweight) and repeated every 4 hours as required. |
| Salbutamol solution for infusion 5mg/5ml: Adults: The recommended dose is 250 micrograms (4 micrograms/kg bodyweight) injected slowly. If necessary, the dose may be repeated. 250 micrograms in 5 mL (50 micrograms/mL) are suitably a dilute preparation for slow intravenous injection. |
| Salbutamol respirator solution 5 mg/ml – for use with nebulizer: Intermittent treatment – Adults and adolescents aged 12 years and over: The usual dose is 0.5 ml to 1 ml of respirator solution (2.5 to 5 mg salbutamol). Some patients may require up to 2 ml (10 mg salbutamol). Intermittent treatment – Children aged 18 months to 12 years: The usual dose is 0.5 ml to 1 ml (2.5 to 5 mg salbutamol) of Ventolin Respirator Solution. Intermittent treatment may be given up to 4 times per day. Continuous treatment: The usual dose is 1 to 2 mg of salbutamol per hour. This dose can be obtained by diluting 1 or 2 ml of respirator solution to 100 ml with sterile normal saline solution to produce a solution containing 50 or 100 micrograms/ml of salbutamol and inhaling the mist from a suitable nebulizer. |
Mechanism of Action:
Salbutamol acts as a functional antagonist to relax the airway irrespective of the spasmogen involved, thus protecting against all bronchoconstrictor challenges. Increased cyclic AMP concentrations are also associated with the inhibition of release of mediators from mast cells in the airway.
Metabolism and half-life
Metabolism: 50% first pass metabolism
- Sulphated in the liver to inactive metabolites
- Urinary elimination of active (30%) drug and inactive metabolites
Half-life is 3-6 hours
Indications
- Relief and prevention of bronchospasm in patients with reversible obstructive airway disease
- Inhalation: Treatment of acute attacks of bronchospasm
- Prevention of exercise-induced bronchospasm
- Unlabelled use: Adjunct in treating serious hyperkalemia in dialysis patients; seems to lower potassium concentrations when inhaled by patients on hemodialysis
Contraindications and cautions
- Contraindicated with hypersensitivity to albuterol; tachyarrhythmias, tachycardia caused by digitalis intoxication; general anesthesia with halogenated hydrocarbons or cyclopropane (these sensitize the myocardium to catecholamines); unstable vasomotor system disorders; hypertension; coronary insufficiency, CAD; history of CVA; COPD patients with degenerative heart disease.
- Use cautiously with diabetes mellitus (large IV doses can aggravate diabetes and ketoacidosis); hyperthyroidism; history of seizure disorders; psychoneurotic individuals; labor and delivery (oral use has delayed second stage of labor; parenteral use of beta2-adrenergic agonists can accelerate fetal heart beat and cause hypoglycemia, hypokalemia, pulmonary edema in the mother and hypoglycemia in the neonate); lactation; the elderly (more sensitive to CNS effects).
Nursing considerations
Assessment
- History: Hypersensitivity to albuterol; tachyarrhythmias, tachycardia caused by digitalis intoxication; general anesthesia with halogenated hydrocarbons or cyclopropane; unstable vasomotor system disorders; hypertension; coronary insufficiency, CAD; history of CVA; COPD patients who have developed degenerative heart disease; diabetes mellitus; hyperthyroidism; history of seizure disorders; psychoneurotic individuals; lactation
- Physical: Weight; skin color, T, turgor; orientation, reflexes, affect; P, BP; R, adventitious sounds; blood and urine glucose, serum electrolytes, thyroid function tests, ECG
Interventions
- Use minimal doses for minimal periods; drug tolerance can occur with prolonged use.
- Maintain a beta-adrenergic blocker (cardio selective beta-blocker, such as atenolol, should be used with respiratory distress) on standby in case cardiac arrhythmias occur.
- Prepare solution for inhalation by diluting 0.5 mL 0.5% solution with 2.5 mL normal saline; deliver over 5–15 min by nebulization.
- Do not exceed recommended dosage; administer pressurized inhalation drug forms during second half of inspiration, because the airways are open wider, and the aerosol distribution is more extensive.
Teaching points
- Do not exceed recommended dosage; adverse effects or loss of effectiveness may result. Read the instructions that come with respiratory inhalant.
- You may experience these side effects: Dizziness, drowsiness, fatigue, headache (use caution if driving or performing tasks that require alertness); nausea, vomiting, change in taste (eat frequent small meals); rapid heart rate, anxiety, sweating, flushing, insomnia.
- Report chest pain, dizziness, insomnia, weakness, tremors or irregular heartbeat, difficulty breathing, productive cough, failure to respond to usual dosage.
2. TERBUTALINE
| Terbutaline |
| Availability: injectable solution (1 mg/mL) oral tablet (2.5 mg; 5 mg) |
| Administration and handling: TABLETS (BRETHINE, BRICANYL) Adults and adolescents aged 15 and over. 2.5 to 5 mg t.i.d. at 6-hr Maximum: 15 mg daily. Children aged 12 to 15. 2.5 mg t.i.d. at 6-hr intervals. Maximum: 7.5 mg daily. Children aged 6 to 11. 50 to 75 mcg/kg t.i.d. at 6-hr Maximum:150 mcg/kg/dose or 5 mg daily. SUBCUTANEOUS INJECTION (BRICANYL) Adults and children aged 12 and over. Initial: 0.25 mg, 15 to 30 min. Maximum: 0.5 mg/4-hr period. Children aged 6 to 12. 5 to 10 mcg (0.005 to 0.01 mg)/kg every 15 to 20 min, up to 3 doses. Maximum: 400 mcg (0.4 mg)/dose. INHALATION AEROSOL (BRETHAIRE) Adults and children. 2 inhalations (400 mcg) every 4 to 6 hr. I NHALATION AEROSOL (BRICANYL TURBUHALER) Adults and children. 1 inhalation (500 mcg), repeated after 5 min. Maximum: 6 inhalations daily |
Mechanism of Action
Stimulates beta2-adrenergic receptors in the lungs, which is believed to increase production of cAMP. The increased cAMP level relaxes bronchial smooth muscles, thereby increasing bronchial airflow and relieving bronchospasm
Indications
Bronchospasm in reversible obstructive airway disease
Contraindications
Hypersensitivity to terbutaline, other sympathomimetic amines, or their components
Adverse Reactions
- CNS: Anxiety, dizziness, drowsiness, headache, insomnia, light-headedness, nervousness, restlessness, tremor, weakness
- CV: Chest pain, irregular heartbeat, palpitations, tachycardia
- ENT: Dry mouth, taste perversion
- ENDO: Hyperglycemia GI: Heartburn, nausea, vomiting
- MS: Muscle spasms
- RESP: Dyspnea
- SKIN: Diaphoresis, flushing, rash
Nursing Considerations
- Use terbutaline cautiously in patients with cardiovascular disease because drug can adversely affect cardiovascular function. Monitor patient’s heart rate and rhythm and blood pressure and assess for chest pain.
- For subcutaneous use, inject into lateral deltoid area.
- Assess patient’s respiratory rate, depth, and quality; oxygen saturation; and activity tolerance at regular intervals because continuous use of beta2-agonists for 12 months or longer accelerates the decline in pulmonary function.
PATIENT TEACHING
- Teach patient how to use terbutaline aerosol inhaler or give subcutaneous injection, as needed.
- Instruct patient not to increase dose or frequency without consulting prescriber.
- Urge patient to seek immediate medical attention if symptoms worsen.
- Inform patient that she may experience transient nervousness or tremors during terbutaline therapy.
3. SALMETEROL
| Salmeterol |
| Availability: inhalation powder (50 mcg) |
| Administration and handling: Adults and children older than age 4: 50 mcg (one inhalation) b.i.d. approximately 12 hours. Adults and children older than age 4: 50 mcg (one inhalation) 30 to 60 minutes before exercise. Withhold additional doses for at least 12 hours. |
| Mechanism of Action: Attaches to beta2 receptors on bronchial cell membranes, stimulating the intracellular enzyme adenylate cyclase to convert adenosine triphosphate to cAMP. The resulting increase in intracellular cAMP level relaxes bronchial smooth muscle cells, stabilizes mast cells, and inhibits histamine release. |
| Contraindications ● Hypersensitivity to drug or its components ● Acute asthma attack |
| Precautions ● cardiovascular disease, diabetes mellitus, hyperthyroidism ● concurrent use of MAO inhibitors or tricyclic antidepressants (extreme caution required) ● pregnant or breastfeeding patients ● children younger than age 4. |
| Indications To prevent asthma-induced bronchospasm |
NURSING CONSIDERATIONS
BASELINE ASSESSMENT
Question history of cardiac disease, hepatic impairment, seizure disorder. Screen for concomitant medications known to prolong QT interval. Assess lung sounds, vital signs.
INTERVENTION/EVALUATION
Monitor rate, depth, rhythm, type of respiration; quality/rate of pulse, B/P. Assess lungs for wheezing, rales, rhonchi. Periodically evaluate serum potassium levels.
PATIENT/FAMILY TEACHING
- Remind patient that drug isn’t a rescue bronchodilator and won’t give immediate relief in emergency.
- Teach patient proper technique for using inhaler or Diskus. Instruct him not to exhale into device or use a spacer with Diskus.
- Advise patient to keep Diskus dry. Tell him not to rinse, wash, or take it apart.
- Instruct patient to take regular doses 12 hours apart. Tell him to take doses for exercise-induced bronchospasm 30 to 60 minutes before exercising.
- Advise patient to take drug exactly as prescribed and not to exceed one inhalation twice daily.
- Tell patient to consult prescriber if he needs more inhalations than usual.
- Caution patient not to stop taking drug without consulting prescriber.
- As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and herbs mentioned above.
4.FORMOTEROL
| Formoterol |
| Availability Inhalation 20 mcg/2 mL vial of inhalation solution |
| Administration and handling: POWDER FOR ORAL INHALATION Adults and children aged 5 and over. 12 mcg every 12 hr. Maximum: 24 mcg daily. POWDER FOR ORAL INHALATION Adults and adolescents aged 12 and over 12 mcg at least 15 min before exercise every 12 hr PRN. Maximum: 24 mcg daily. POWDER FOR ORAL INHALATION Adults. 12 mcg every 12 hr through inhaler device. Maximum: 24 mcg daily. SOLUTION FOR ORAL INHALATION Adults. 20 mcg b.i.d. by nebulization. Maximum: 40 mcg daily. Administration ● Be aware that drug is not intended for acute asthma attacks. ● Use capsules only with Aerolizer inhaler supplied. ● Keep capsules in blister until immediately before use. |
| Mechanism of Action Selectively attaches to beta2 receptors on bronchial membranes, stimulating the intracellular enzyme adenyl cyclase to convert adenosine triphosphate to cAMP. The resulting increase in the intracellular cAMP level relaxes bronchial smooth muscle cells, stabilizes mast cells, and inhibits histamine release. |
| Contraindications Acute asthma, hypersensitivity to formoterol fumarate or its components |
| Precautions ● acute asthma symptoms, deteriorating asthma, cardiovascular disorders, seizure disorders, thyrotoxicosis, diabetes, possible hypokalemia ● patients older than age 75 ● labor ● pregnant or breastfeeding patients ● children younger than age 5. |
| Indications Long term maintenance of asthma; prevention or long-term maintenance of bronchospasm in patients with chronic obstructive pulmonary disease |
Patient monitoring
- Monitor pulmonary function test results.
- Monitor potassium and glucose levels. Patient teaching
- Teach patient how to use capsules and Aerolizer inhaler provided.
- Instruct patient to keep capsules in blisters until immediately before use.
- Caution patient not to swallow capsules.
- Tell patient not to use drug for acute asthma attacks.
- Instruct patient to contact prescriber immediately if difficulty in breathing persists after using drug or if condition worsens.
- Caution patient to take drug exactly as prescribed and not to stop therapy even if he feels better.
- Tell patient to consult prescriber if he has been taking inhaled, short-acting drugs on a regular basis.
- Advise female patient to tell prescriber if she is pregnant or breastfeeding or if she plans to become pregnant.
- Caution patient to avoid alcohol during therapy.
- As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs, tests, and behaviors mentioned above
Nursing Considerations
- Administer formoterol capsules or solution only by oral inhalation.
- Store capsules and solution in their original packaging, and open immediately before use.
- To use delivery system for powder form, place capsule in well of inhaler device. Press and release buttons on side of device to pierce capsule. Have patient inhale rapidly and deeply through mouthpiece; drug is dispersed into airways as patient inhales.
- Give inhalation solution only by standard jet nebulizer and air compressor.
5.BAMBUTEROL
| Bambuterol |
| Availability: Oral 10mg tablets |
| Administration and handling: Oral 10 mg tablets |
| Mechanism of Action: Bambuterol is a prodrug of terbutaline. It relaxes bronchial smooth muscle by selectively acting on β2-receptors. |
| Contraindications Children under 18 years Galactosaemia Hypertrophic cardiomyopathy |
| Precautions: ●Predisposition to hypokalaemia ● Breastfeeding ●Cardiac arrhythmias ●Diabetes mellitus ●First trimester of pregnancy ●Glucose-galactose malabsorption syndrome ●Hypertension ●Hyperthyroidism ●Hypokalaemia ●Hypoxia ●Ischaemic heart disease ●Lactose intolerance ●Narrow angle glaucoma ●Pregnancy at term ●Renal impairment – glomerular filtration rate below 50ml/minute ●Severe hepatic impairment ●Thyrotoxicosis |
| Indications: Reversible airways obstruction |
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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