What are the recommended intravenous (IV) medications for acute anxiety?

Recommended IV Medications for Acute Anxiety

For acute anxiety management in adults, intravenous benzodiazepines are the first-line treatment, with midazolam (2.5-5 mg IV) and lorazepam (1-2 mg IV) being the preferred agents due to their rapid onset and established safety profiles. 1, 2, 3

First-Line IV Anxiolytics

Midazolam

• Dosing: 2.5 mg IV initially (up to 5 mg maximum)
• Onset: 2-5 minutes
• Duration: 3-11 hours
• Advantages:
  • Rapid onset of action
  • Shorter half-life than lorazepam
  • Can be given IM if IV access unavailable
• Precautions:
  • Monitor for respiratory depression, especially when combined with opioids
  • Reduce dose in elderly, frail patients, or those with COPD (0.5-1 mg)
  • May cause paradoxical agitation in some patients 1, 2, 4

Lorazepam

• Dosing: 1 mg IV initially (up to 2 mg maximum)
• Onset: 15-20 minutes
• Duration: 8-15 hours
• Advantages:
  • Longer duration of action than midazolam
  • No active metabolites
  • Less likely to accumulate in hepatic impairment
• Precautions:
  • Reduce dose in elderly or frail patients (0.25-0.5 mg)
  • Monitor for respiratory depression
  • Propylene glycol-related acidosis with prolonged use 1, 3

Patient-Specific Considerations

Age-Based Dosing

• Elderly patients: Start with lower doses (midazolam 0.5-1 mg IV or lorazepam 0.25-0.5 mg IV)
• Young adults: Standard dosing as above

Comorbidity Considerations

• Respiratory disease: Use caution with benzodiazepines; consider reduced doses
• Hepatic impairment: Prefer lorazepam; reduce midazolam dose
• Renal impairment: Standard dosing for acute administration, but avoid repeated dosing 3

Drug Interactions

• Opioid co-administration: Reduce benzodiazepine dose by 50% due to increased risk of respiratory depression
• P450 inhibitors: Reduce midazolam dose when used with CYP3A4 inhibitors 2, 4

Monitoring and Safety

• Vital signs: Monitor respiratory rate, oxygen saturation, blood pressure
• Equipment: Ensure availability of airway management equipment
• Antidote: Have flumazenil available for reversal of benzodiazepine effects in case of severe respiratory depression 4, 5

Special Situations

Severe Agitation with Psychosis

• Consider adding an antipsychotic (e.g., haloperidol 2-5 mg IV) to benzodiazepine therapy 1

Alcohol or Benzodiazepine Withdrawal

• Benzodiazepines are treatment of choice as monotherapy 1

Delirium Risk

• Use caution as benzodiazepines may worsen or precipitate delirium
• Consider lower doses and shorter-acting agents 1

Common Pitfalls to Avoid

1. Oversedation: Start with lower doses and titrate to effect
2. Respiratory depression: Particularly when combined with other CNS depressants
3. Paradoxical reactions: Increased agitation can occur, especially in elderly
4. Prolonged sedation: Consider the context and need for continued alertness
5. Undertreatment: Insufficient dosing may fail to control symptoms and lead to escalation

For long-term anxiety management, transition to SSRIs or SNRIs which are more appropriate for chronic anxiety disorders 1, 6.