Atenolol

Atenolol

[tablets 1 cent each]

ADMINISTRATION ROUTES:

• PO, NG

ALTERNATIVE NAMES:

• Noten

ICU INDICATIONS:

1. hypertension
2. acute myocardial infarction
3. secondary prevention in patients with coronary artery disease
4. angina
5. rate control

PRESENTATION AND ADMINISTRATION:

• PO/ NG:
  Pacific atenolol: orange 50mg and 100mg tablets.
  Tablets may be crushed and administered via nasogastric tube.

DOSAGE:

• PO:
  Commence at 50mg daily; increase to 100mg daily as tolerated.
  Note: generally metoprolol is used as the 1st line beta blocker rather than atenolol in our ICU

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

• Dose in renal impairment [GFR (ml/min)]
  <10: 50mg once daily
  10-20: dose as in normal renal function
  >20-50: dose as in normal renal function
• Dose in renal replacement therapy
  CAPD: 50mg once daily
  HD: 50mg once daily
  CVVHDF: dose as in normal renal function

DOSAGE IN PAEDIATRICS:

• Safety and effectiveness in paediatric patients have not been established 1-2mg/kg PO 12-24hrly.

CLINICAL PHARMACOLOGY:

• Atenolol is a beta1-selective (cardioselective) beta-adrenergic receptor blocking agent without membrane stabilizing or intrinsic sympathomimetic (partial agonist) activities. This preferential effect is not absolute, however, and at higher doses, atenolol inhibits beta2-adrenoreceptors, chiefly located in the bronchial and vascular musculature. Absorption of an oral dose of atenolol is rapid and consistent but incomplete. Approximately 50% of an oral dose is absorbed from the gastrointestinal tract, the remainder being excreted unchanged in the faeces. Peak blood levels are reached between 2 and 4 hours after ingestion.

CONTRAINDICATIONS:

1. sinus bradycardia
2. heart block greater than first degree
3. cardiogenic shock
4. overt cardiac failure
5. asthma

WARNINGS

• Cardiac Failure:
  Sympathetic stimulation is necessary in supporting circulatory function in congestive heart failure, and beta blockade carries the potential hazard of further depressing myocardial contractility and precipitating more severe failure.
• Discontinuation of therapy:
  Discontinuation of therapy in a patient with coronary artery disease may lead to rebound angina, arrhythmia or myocardial infarction.
• Diabetes and Hypoglycemia:
  Beta blockers may mask tachycardia occurring with hypoglycaemia.
• Thyrotoxicosis:
  Beta-adrenergic blockade may mask certain clinical signs (e.g., tachycardia) of hyperthyroidism. Abrupt withdrawal of beta blockade might precipitate a thyroid storm.

PRECAUTIONS

• General:
  Atenolol may aggravate peripheral arterial circulatory disorders.
• Laboratory Tests:
  No tests in addition to routine ICU tests are required
• Drug/Laboratory Test Interactions :
  None known

IMPORTANT DRUG INTERACTIONS FOR THE ICU

• Beta blockers may exacerbate the rebound hypertension which can follow the withdrawal of clonidine

ADVERSE REACTIONS

• Body as a Whole:
  Tiredness, Fatigue
• Cardiovascular System:
  Bradycardia , Cold extremities, Hypotension, Leg pain
• Respiratory System:
  Wheeziness, Dyspnoea
• Digestive System:
  Diarrhoea, Nausea
• Nervous System:
  Dizziness, Vertigo, Light-headedness