What is a suitable anxiolytic for a 71-year-old patient taking Zyprexa (olanzapine) and mirtazepine, experiencing anxiety before an MRI without anesthesia?

Single-Dose Anxiolytic for Pre-MRI Anxiety in a 71-Year-Old on Olanzapine and Mirtazapine

For this 71-year-old patient on olanzapine and mirtazapine requiring acute anxiolysis before MRI, lorazepam 0.25-0.5 mg orally is the recommended single-dose anxiolytic, with careful monitoring for sedation and avoiding benzodiazepines if possible due to age-related risks.

Primary Recommendation: Low-Dose Lorazepam with Caution

• Lorazepam 0.25-0.5 mg orally is the preferred benzodiazepine for elderly patients requiring acute anxiolysis, as it has a relatively short half-life and no active metabolites 1, 2.
• The dose must be reduced to 0.25-0.5 mg in elderly patients (maximum 2 mg in 24 hours) compared to younger adults 1.
• Lorazepam tablets can be used sublingually for faster onset if needed 1.

Critical Safety Considerations in This Patient

• The American Society of Clinical Oncology specifically advises avoiding combining benzodiazepines with olanzapine when possible, as fatalities have been reported with concurrent use 3.
• This patient's combination of olanzapine and mirtazapine already provides significant sedation, increasing risk of excessive CNS depression with benzodiazepine addition 3, 4.
• The American Geriatrics Society Beers Criteria strongly recommend avoiding benzodiazepines in patients ≥65 years due to increased risk of cognitive impairment, delirium, and falls 1.

Alternative First-Line Option: Melatonin

• Melatonin (tablets or sublingual) provides effective preoperative anxiolysis with high-grade quality evidence and minimal side effects compared to placebo 1.
• Melatonin is equally effective to midazolam for preoperative anxiety with a superior safety profile in elderly patients 1.
• This represents the safest option given the patient's age and current medication regimen 1.

Specific Dosing Algorithm

If benzodiazepine is deemed necessary:

• Start with lorazepam 0.25 mg orally 30-60 minutes before MRI 1, 2.
• Maximum single dose should not exceed 0.5 mg in this elderly patient 1.
• Monitor closely for sedation, orthostatic hypotension, and respiratory depression 3.

If choosing melatonin (preferred):

• Administer 3-5 mg orally 60-90 minutes before the procedure 1.

Medications to Avoid

• Alprazolam should be avoided despite its anxiolytic properties, as it is not recommended in the UK for long-term use and carries higher risks in elderly patients 5.
• Midazolam is inappropriate for oral single-dose use in this outpatient setting 1.
• Higher potency or longer-acting benzodiazepines (diazepam, clonazepam) carry greater risk of prolonged sedation and falls in elderly patients 2, 6.

Key Clinical Pitfalls

• Elderly patients are especially sensitive to benzodiazepine effects, with increased risk of psychomotor impairment even after single-dose administration 1.
• The combination of mirtazapine (which is sedating) plus olanzapine (also sedating) creates additive CNS depression risk when adding any anxiolytic 1, 7.
• Ensure the patient has a responsible adult to accompany them home, as even low-dose benzodiazepines can impair motor function 1.

Non-Pharmacological Adjuncts

• Effective communication strategies and explanation of the MRI procedure can successfully reduce patient anxiety 1.
• Consider music therapy, aromatherapy, or relaxation techniques as adjuncts to reduce anxiety without additional medication 1.