What is the typical dosing schedule (sig) for alprazolam (Xanax) 0.5 mg for treating panic attacks?

Alprazolam 0.5 mg Dosing for Panic Attacks

For panic attacks, start alprazolam 0.5 mg three times daily (TID), with dose increases of no more than 1 mg per day every 3-4 days as needed, targeting a typical effective dose range of 5-6 mg daily in divided doses. 1

Initial Dosing Strategy

• Begin with 0.5 mg orally three times daily to minimize adverse effects while establishing therapeutic benefit 1
• Distribute doses evenly throughout waking hours (every 6-8 hours) to prevent interdose breakthrough symptoms 1
• The 0.5 mg starting dose is appropriate for most patients with panic disorder, though some clinicians may initiate at 0.25 mg TID in elderly or debilitated patients 2

Dose Titration Protocol

• Increase dose by no more than 1 mg per day at intervals of 3-4 days based on clinical response 1
• Target dose for panic disorder typically ranges from 5-6 mg daily in divided doses (e.g., 1.5-2 mg three times daily) 1
• Some patients require doses up to 10 mg daily for complete panic attack suppression, though most respond to 4-6 mg daily 1
• Slower titration is advisable when approaching doses greater than 4 mg daily to allow full pharmacodynamic expression 1

Therapeutic Monitoring

• Optimal panic attack suppression occurs at steady-state plasma concentrations of 20-40 ng/mL, which typically corresponds to daily doses of 2-4 mg 3, 4
• Complete remission of spontaneous panic attacks occurs in 70% of patients with plasma levels >20 ng/mL versus only 31% with levels <20 ng/mL 4
• Clinical studies demonstrate 85% complete remission of panic attacks at mean doses of 2.2 mg daily, with panic cessation occurring within an average of 6 days 5
• Steady-state plasma concentrations change by approximately 10-12 ng/mL for each 1 mg/day dosage adjustment 3

Special Population Considerations

• Elderly patients: Start with 0.25 mg 2-3 times daily due to reduced clearance and increased sensitivity to benzodiazepines 2
• Hepatic impairment: Use lower starting doses (0.25 mg 2-3 times daily) as clearance is significantly reduced in cirrhosis 3
• Renal disease: While dose adjustment is not strictly required, monitor for increased free fraction due to reduced protein binding 3

Critical Safety Warnings

• Never abruptly discontinue alprazolam due to high risk of withdrawal seizures and rebound panic 1, 6
• When tapering, decrease by no more than 0.5 mg every 3 days; some patients require even slower reduction 1
• During withdrawal, 88% of patients experience recurrent or increased panic attacks, and 53% develop new withdrawal symptoms (malaise, weakness, insomnia, tachycardia, lightheadedness) 6
• Reassess need for continued treatment frequently, particularly for doses exceeding 4 mg daily 1

Common Pitfalls to Avoid

• Avoid once-daily dosing: Alprazolam's 9-16 hour half-life necessitates divided dosing (TID or QID) to prevent interdose anxiety breakthrough 3, 7
• Don't underdose: Many patients require 4-6 mg daily for adequate panic control; stopping titration prematurely at 1-2 mg daily often results in incomplete response 1, 4
• Don't overtitrate too quickly: Rapid dose escalation increases CNS depression side effects without improving efficacy 1, 4
• Monitor for tolerance: After extended treatment periods, consider supervised taper attempts during panic-free intervals 1

Drug Interactions Requiring Dose Adjustment

• Reduce alprazolam dose by 50% or more when coadministering with CYP3A4 inhibitors including cimetidine, fluoxetine, or fluvoxamine, which significantly impair clearance 3
• Propranolol, metronidazole, disulfiram, oral contraceptives, and ethanol do not significantly alter alprazolam pharmacokinetics 3

Expected Timeline and Outcomes

• Peak plasma concentrations occur 0.7-1.8 hours after oral administration with 80-100% bioavailability 3
• Panic attack cessation typically occurs within the first week of treatment at therapeutic doses 5
• Complete remission of panic attacks achieved in 85% of patients at mean doses of 2.2 mg daily 5
• Agoraphobic avoidance behavior resolves in approximately 91% of patients treated with alprazolam alone 5