What are the uses and precautions of ephedrine in medical treatment, particularly for hypotension and asthma?

Ephedrine: Medical Uses and Precautions

Ephedrine is primarily indicated for the treatment of clinically important hypotension in anesthetic settings, with secondary uses in nasal congestion, though it requires careful monitoring due to significant cardiovascular effects and contraindications in certain patient populations. 1

Primary Medical Uses

1. Treatment of Hypotension

• FDA-approved indication: Treatment of clinically important hypotension occurring during anesthesia 1
• Dosing for hypotension:
  • Initial dose: 5-10 mg IV bolus
  • Additional boluses as needed, not exceeding 50 mg total
  • Prepare a 5 mg/mL solution by diluting 50 mg (1 mL) with 9 mL of 5% dextrose or 0.9% sodium chloride 1
• Specific applications:
  • Prevention of hypotension during spinal anesthesia for cesarean delivery (5 mg IV can significantly reduce incidence and severity of hypotension) 2
  • Management of refractory hypotension when used alongside other vasopressors 3
  • Both ephedrine and phenylephrine are acceptable for treating hypotension during neuraxial anesthesia 4

2. Bronchodilation

• Can reverse bronchoconstriction during general anesthesia, particularly valuable in patients with asthma or those on beta-blocker therapy 5
• Higher doses (0.6-1.4 mg/kg) are required for neonates and infants under 6 months for treatment of hypotension, with 1.2 mg/kg being the optimal dose 6

Precautions and Contraindications

Cardiovascular Concerns

• Hypertension risk: When used prophylactically, ephedrine has been associated with increased incidence of hypertension 1
• Pulmonary arterial pressure: Both ephedrine and phenylephrine can significantly increase pulmonary arterial pressure when treating hypotension 7
• Tachyphylaxis: Repeated administration can result in decreased effectiveness, requiring alternative pressors 1
• Arrhythmias: Can cause tachycardia, palpitations, reactive hypertension, bradycardia, and ventricular ectopics 1

Special Populations

1. Pregnant patients:

   • Serious postpartum hypertension can occur when used with oxytocic drugs 1
   • Carefully monitor blood pressure in patients receiving both ephedrine and oxytocin 1

2. Patients with hypertension:

   • Oral decongestants containing ephedrine can elevate blood pressure in hypertensive individuals 4
   • Hypertensive patients should be monitored when using decongestants 4

3. Children:

   • Use in infants and young children has been associated with agitated psychosis, ataxia, hallucinations, and even death 4
   • Risks and benefits must be carefully considered before using in children under 6 years 4

Drug Interactions

• Augmented pressor effect with:

  • Oxytocin and oxytocic drugs
  • Clonidine, propofol, MAOIs, atropine 1

• Antagonized pressor effect with:

  • α-adrenergic antagonists
  • β-adrenergic receptor antagonists
  • Reserpine, quinidine, mephentermine 1

• Other interactions:

  • May reduce efficacy of guanethidine
  • May reduce onset time of neuromuscular blockade with rocuronium
  • May decrease efficacy of epidural blockade
  • May increase frequency of adverse effects with theophylline
  • May increase risk of arrhythmias with cardiac glycosides 1

Adverse Effects

• Gastrointestinal: Nausea, vomiting
• Neurological: Dizziness
• Psychiatric: Restlessness
• Cardiovascular: Tachycardia, palpitations, reactive hypertension, bradycardia 1

Practical Considerations

For Anesthesia Use

• Intravenous fluid preloading may be used to reduce frequency of maternal hypotension after spinal anesthesia for cesarean delivery 4
• For postpartum tubal ligation, neuraxial techniques are preferred to general anesthesia, with ephedrine available to treat hypotension 4

For Nasal Congestion

• Topical decongestants containing ephedrine should only be used for short-term or intermittent therapy due to risk of rhinitis medicamentosa 4
• Oral decongestants should be used with caution in patients with arrhythmias, angina pectoris, coronary artery disease, cerebrovascular disease, and hyperthyroidism 4

Monitoring Requirements

• Continuous cardiac monitoring
• Frequent blood pressure measurements
• Regular assessment of tissue perfusion 3

By understanding these uses and precautions, clinicians can appropriately utilize ephedrine while minimizing risks to patients, particularly in anesthetic settings where its vasopressor effects are most valuable.