ATROPINE SULPHATE

Atropine

 Reviewed by Dr Carl Kuschel, Dorothy Cooper
August 1998
Administration Newborn Drug Protocol Index Newborn Services Home Page

Dose and Administration

  1. 10-30 micrograms/kg/dose IV over 1 minute, IM or ETT (ETT route to be used only if IV route not possible).
  2. Dose may be repeated every 10-15 minutes to achieve desired effect, with a maximum total dose of 40 micrograms/kg.

Indications

  1. Severe sinus bradycardia, particularly when parasympathetic influences on the heart (digoxin, beta blocker drugs, hyperactive carotid sinus reflex) predominate.
  2. To reduce the muscarinic effects of neostigmine when reversing neuromuscular blockade.
  3. Prevention of reflex bradycardia during intubation.

Contraindications and Precautions

  1. Known hypersensitivity to atropine.
  2. Abdominal distension with decreased peristalsis and/or intestinal obstruction.
  3. Gastroesophageal reflux.
  4. Obstructive uropathy.
  5. Congenital glaucoma.
  6. Caution in patients with Down Syndrome.

Clinical Pharmacology

Atropine, a naturally occurring alkaloid, is an anticholinergic agent. Acts by competitive inhibition of the actions of acetylcholine on muscarinic receptors. Increases heart rate by decreasing the effects of the parasympathetic system while increasing the effects of the sympathetic system. Vagal influences on the gastrointestinal tract are partially inhibited by atropine. Motor activity in the stomach and small and large intestines is reduced. Oesophageal sphincter tone is reduced. Salivary secretion is inhibited. Atropine relaxes bronchial and bronchiolar smooth muscle, thereby reducing airway resistance and increasing dead space by 30%.

Rapid absorption from intestinal tract but not the stomach. Pharmacological activity of parenteral administration is 2-3 times greater than enteral administration. Low binding (20%) to human plasma protein. Excreted mainly unchanged via the urine.

Rapid onset of action. Peak effects: cardiovascular (12-16 minutes), gastrointestinal tract (1-2 hours). Duration  of action 4-6 hours.

Possible Adverse Effects

  1. Tachycardia
  2. Urinary retention
  3. Impaired gastrointestinal motility
  4. Hyperthermia
  5. Hot, dry scarlet flushed skin
  6. Cardiac arrhythmias
  7. Dry mucous membranes, dry mouth

Special Considerations

  1. Limited use in newborn infants. Should not be used in neonatal resuscitation.
  2. Management of atropine toxicity: stop atropine, treat anticholinergic symptoms with physostigmine 0.5 mg by slow IV infusion.
  3. Sodium chloride content 9mg.