Alprazolam: dosage

Alprazolam comes as regular tablets, orally disintegrating tablets, and extended-release tablets. Regular and orally disintegrating tablets come in 0.25 mg, 0.5 mg, 1 mg, and 2 mg strengths; extended-release comes in 0.5 mg, 1 mg, 2 mg, and 3 mg [1].

For generalized anxiety, the usual starting dose is 0.25–0.5 mg three times daily [2]. For panic disorder, it's 0.5 mg three times daily [2], with increases no more than every 3–4 days and no more than 1 mg/day per increase [2]. Across indications, any dose increase should happen no more than once every 3–4 days [3]. The maximum recommended daily dose is 4 mg, split across multiple doses [2]. Guidance is to use the lowest dose that works and to keep checking whether continued use is still needed [2].

If you're tapering off, standard guidance is to cut by no more than 0.5 mg every 3 days [2], and some people need to go slower than that [2].

Absorption is fast — peak serum levels are reported to occur within roughly 0.7 to 2.1 hours [4][5] — and oral bioavailability averages 80–100% [5]. After a single 1 mg dose, peak blood levels land in a fairly wide range (12–22 micrograms/L) [5], reached somewhere between roughly 0.7 and 1.8–2.1 hours depending on the study [4][5]. Reported elimination half-life estimates range from about 9 to 16 hours depending on the source [4][5].

Clearance is slower in older adults [5] and significantly slower in people with cirrhosis [5]. Cimetidine, fluoxetine, fluvoxamine, and propoxyphene significantly impair alprazolam's clearance, raising its levels ; strong CYP3A inhibitors like ketoconazole and itraconazole are contraindicated with alprazolam entirely, with ritonavir as an exception to that rule [2]. Moderate or weak CYP3A inhibitors can also raise alprazolam levels and adverse-reaction risk [2]. Higher steady-state levels track with more frequent side effects [5].

References

1. Alprazolam - StatPearls — NCBI Bookshelf, National Institutes of Health
2. XANAX (alprazolam) tablet — FDA prescribing information — DailyMed (U.S. National Library of Medicine)
3. Alprazolam: MedlinePlus Drug Information — MedlinePlus, National Library of Medicine
4. Alprazolam: pharmacokinetics, clinical efficacy, and mechanism of action — PubMed (Journal article)
5. Clinical pharmacokinetics of alprazolam. Therapeutic implications — Clinical Pharmacokinetics (Springer)