Beta- adrenoceptor Antagonists ( β – Blockers)
Mechanism of Action:
Block activation of β- adrenoceptors (predominantly mediated through β -1 antagonism). Thereby reducing the exceptionally – induced rise in heart rate and reducing cardiac contractility. This reduces systolic BP and myocardial O2 demand.
Indications:
- Angina
- Arrhythmias
- Hypertension
- Heart failure (bisoprolol and Carvedilol only)
- Prophylaxis post- MI
- Migraine Prophylaxis
- Thyrotoxicosis Anxiety
- Coronary artery disease
- Myocardial infarction
- Essential tremor
- Glaucoma
- Migraine attacks
| Atenolol |
| Availability: Tablets: 25 mg, 50 mg, 100 mg. |
| Administration/handling: PO: • Give without regard to food. • Tablets may be crushed. |
| Hypertension PO: Adults: Initially, 25–50 mg once daily. After 1–2 weeks, may increase dose up to 100 mg once daily. Elderly: Usual initial dose, 25 mg/day. Children: Initially, 0.5–1 mg/kg/dose given once daily. Range: 0.5–1.5 mg/kg/day. Maximum: 2 mg/kg/day up to 100 mg/day. |
| Angina Pectoris PO: Adults: Initially, 50 mg once daily. May increase dose up to 200 mg once daily. Elderly: Usual initial dose, 25 mg/day |
| Post-MI PO: ADULTS: 100 mg once daily or 50 mg twice daily. Begin within first 24 hrs post-MI, then continue indefinitely |
| Bisoprolol |
| Availability: Tablets: 5 mg, 10 mg |
| Administration/handling: PO: • Give without regard to food. |
| Hypertension PO: Adults, elderly: Initially, 2.5–5 mg once daily. May increase to 10 mg, then to 20 mg once daily. Usual dose: 5–10 mg once daily. |
| Dosage in renal impairment: CrCl less than 40 mL/min: Adults, elderly: Initially, give 2.5 mg. Dosage in Hepatic Impairment Cirrhosis, hepatitis: Initially, 2.5 mg. |
| Propranolol |
| Availability: Injection Solution: 1 mg/mL. Oral Solution: 20 mg/5 mL, 40 mg/5 mL. Oral Solution: 4.28 mg/mL. Tablets: 10 mg, 20 mg, 40 mg, 60 mg, 80 mg. Capsules, Sustained-Release: 60 mg, 80 mg, 120 mg, 160 mg. |
| Administration/handling: IV Reconstitution • Give undiluted for IV push. • For IV infusion, may dilute each 1 mg in 10 mL D5W. Rate of administration • Do not exceed 1 mg/min injection rate. • For IV infusion, give over 30 min. Storage • Store at room temperature. • Once diluted, stable for 24 hrs at room temperature. PO • May crush scored tablets. • Do not break, crush, or open extended- or sustained-release capsules. • Give immediate release tablets on empty stomach. • Give extended-release, sustained-release without regard to food. |
| Hypertension PO: Adults, elderly: (Immediate-Release or Extended-Release): Initially, 80 mg/day. May increase at greater than or equal to 1-wk intervals prn based on patient response. Usual dosage range: 80–160 mg/day. |
| Angina PO: Adults, elderly: (Immediate Release): Initially, 80 mg/day. Increase dose as tolerated to desired effect. Range: 80–320 mg/day in 2–4 divided doses. |
| Arrhythmia IV: Adults, elderly: 1–3 mg. Repeat q2–5min up to total of 5 mg. CHILDREN: 0.01–0.15 mg/kg. May repeat q6–8h. Maximum: Infants, 1 mg/dose; children, 3 mg/dose. PO: Adults, elderly: (Immediate Release): 10–40 mg 3–4 times/day. Children: Initially, 0.5–1 mg/kg/day in divided doses q6–8h. May increase q3days. Usual dosage: 2–4 mg/kg/day. Maximum: 16 mg/kg/day or 60 mg/day. |
| Reduction of Cardiovascular Mortality, Reinfarction in Pts with Previous MI PO: Adults, elderly: (Immediate-Release): Initially, 60–120 mg/day in 2–3 divided doses. May increase dose based on heart rate and BP up to 240 mg/day |
| Labetalol |
| Availability: Injection Solution: 5 mg/ml. Tablets: 100 mg, 200 mg, 300 mg. |
| Administration/handling: IV: Prolonged duration of action: Monitor several hours after administration. Excessive administration may result in prolonged hypotension and/or bradycardia. |
| Reconstitution • For IV infusion, dilute in D5W to provide concentration of 1–2 mg/ml. Rate of administration: • For IV push, administer at a rate of 10 mg/min. • For IV infusion, administer at rate of 2 mg/min initially. Rate is adjusted according to B/P. • Monitor B/P immediately before and q5–10min during IV administration (maximum effect occurs within 5 min). Storage: • Store at room temperature. • After dilution, IV solution is stable for 72 hrs. • Solution appears clear, colorless to light yellow. • Discard if discolored or precipitate forms. PO: • Give without regard to food. • Tablets may be crushed. |
| Hypertension: PO: Adults, elderly: Initially, 100 mg twice daily. Adjust in increments of 100 mg twice daily q2–3days. Usual dose: 200–800 mg/day in 2 divided doses. May require up to 2,400 mg/day. Children: 1–3 mg/kg/ day in 2 divided doses. Maximum: 10– 12 mg/kg/day up to 1,200 mg/day. |
| Severe Hypertension, Hypertensive Crisis: IV: Adults: Initially, 10–20 mg (bolus over 2 min). Additional doses of 40–80mg may be given at 10-min intervals, up to total dose of 300 mg. Children: 0.2–1 mg/kg/dose. Maximum: 40 mg/dose. IV infusion: Adults: Initially, 0.5–2 mg/ min up to 10 mg/min. Children: 0.25–3 mg/kg/hr. Maximum: 3 mg/kg/hr. |
Cautions and Contraindications:
- •Asthma, COPD, diabetes, Raynaud’s disease, hepatic & renal impairment.
- •Decompensated heart failure
- •Bradycardia, sick sinus syndrome, second or third – degree heart block
- •Hypotension/ cardiogenic shock
- •Severe peripheral arterial disease
Side – Effects:
- Bronchospasm
- Fatigue
- Cold peripheries
- Bradycardia and hypotension
- Sleep disturbances
- Reduced glucose tolerance
- Hyperkalemia
- Sexual dysfunction in males
- Dizziness and headache
- Heart block
- Depression
- Hallucination
- Hypoglycemia
Metabolism and Half- Life:
Variable – e.g., atenolol (t ½ 6h) is excreted largely unchanged in the urine. Propranolol (t ½ 4h) is metabolized by the liver.
Monitoring:
- Monitor clinically for adverse effects.
- Monitor HR, BP, ECG regularly and evaluate therapeutic response.
Drug Interactions:
- Enhanced Hypotensive effects with antihypertensives and alcohol.
- Hypotensive effect antagonized by NADIDs, steroids and estrogens.
- May mask warning signs of hypoglycemia in diabetics.
- Increased risk of AV block and heart failure with verapamil and diltiazem.
NURSING CONSIDERATIONS
BASELINE ASSESSMENT:
- Vital signs, lab results: renal & hepatic function, electrolytes, blood glucose and lipid panel.
- If medication is prescribed for
- Hypertension: orthostatic hypotension
- Angina: frequency & duration
- Arrhythmia: ECG
- Heart failure : weight, lung sounds, presence of edema or dyspnea.
Client Education:
- •Hypotension can occur – change position slowly
- •Can mask hypoglycemia symptoms- check blood glucose levels and to be aware of other symptoms.
- •Should not abruptly stop medication.
- •Dietary modifications, regular activity, weight control, moderate alcohol intake, smoking cessation
Important Points:
- Cardioselectivity: atenolol, bisoprolol and nebivolol have less effect on β 2 receptors and therefore reduced bronchospasm.
- Lipid solubility: atenolol and sotalol are most water- soluble, therefore less able to cross blood – brain barrier resulting in less sleep disturbance.
- Half- life: atenolol, bisoprolol and carvedilol have a longer duration of action hence only need to be taken once daily.
- Additional effects: sotalol is a mixed class II/III antiarrhythmic (requires monitoring of QT interval due to risk of torsades de pointes)
- Nebivolol causes peripheral vasodilation (mediated by nitric oxide.)
- Intravenous labetalol can be used as a treatment for hypertensive emergencies, particularly those associated with pregnancy.
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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