What is the best approach for a patient with frequent anxiety, currently taking alprazolam (Xanax) 0.5mg as needed, every day, to switch to lorazepam (Ativan)?

Switching from Alprazolam 0.5mg PRN to Lorazepam

For a patient taking alprazolam 0.5mg PRN most days, switch directly to lorazepam 1mg PRN using the same frequency, as this represents an equivalent dose conversion (1:2 ratio of alprazolam to lorazepam). 1

Dose Conversion and Rationale

• The standard equipotent conversion ratio is 1mg alprazolam = 2mg lorazepam, making 0.5mg alprazolam equivalent to 1mg lorazepam 2
• Since the patient is using PRN dosing (not scheduled), a direct substitution approach is appropriate rather than a gradual cross-taper 1
• The lorazepam dose of 1mg falls within the recommended PRN range of 0.5-1mg every 4-6 hours for acute anxiety, with a maximum of 4mg/24 hours 3

Practical Switching Instructions

• Instruct the patient to simply replace each 0.5mg alprazolam dose with 1mg lorazepam on an as-needed basis 1
• Maintain the same PRN frequency pattern the patient has established (most days of the week) 1
• No tapering is required for PRN users who are not taking scheduled daily doses, as physical dependence is less likely with intermittent use 4

Important Counseling Points

• Warn the patient that lorazepam has a longer duration of action (10-20 hours) compared to alprazolam (6-12 hours), which may provide more sustained anxiety relief but could cause more daytime sedation 2
• Approximately 10% of patients may experience paradoxical agitation with benzodiazepines, including lorazepam 3, 5
• Anxious patients commonly attribute new anxiety symptoms to medication changes (negative placebo response), particularly those with somatization tendencies—reassure the patient this is normal during transitions 6

Monitoring and Follow-up

• Schedule follow-up within 1-2 weeks to assess efficacy and tolerability of the new regimen 2
• If the patient reports inadequate anxiety control, the dose can be adjusted within the range of 0.5-1mg PRN, though 1mg is the appropriate starting equivalent 3
• For elderly or debilitated patients, reduce the initial lorazepam dose to 0.5mg PRN (maximum 2mg/24 hours) 3, 1

Critical Prescribing Caveats

• Avoid combining lorazepam with other sedatives due to significantly increased respiratory depression risk 3
• Regular benzodiazepine use can lead to tolerance, addiction, depression, and cognitive impairment—this switch does not eliminate these risks 3
• If the patient later wishes to discontinue lorazepam entirely, use a gradual taper (reducing by 10% every 3 days to weekly) to minimize withdrawal reactions 1, 7