XANAX XR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for XANAX XR (XANAX XR).
Benzodiazepine that enhances GABA-A receptor activity by increasing the frequency of chloride channel opening, leading to neuronal hyperpolarization and reduced excitability.
| Metabolism | Hepatic via CYP3A4; active metabolite alprazolam does not accumulate significantly. |
| Excretion | Renal excretion of unchanged drug and metabolites accounts for approximately 80-90% of the dose. Fecal excretion is minimal (<10%). |
| Half-life | Mean terminal elimination half-life is 11.2 hours (range 6.3-15.8 hours). The extended-release formulation provides sustained therapeutic concentrations with once-daily dosing. |
| Protein binding | 80% bound to serum albumin. |
| Volume of Distribution | Approximately 1.1 L/kg (range 0.9-1.3 L/kg), indicating extensive tissue distribution. |
| Bioavailability | Oral: Approximately 90% (absolute bioavailability). |
| Onset of Action | Oral: Onset of anxiolytic effect occurs within 1-2 hours post-dose due to extended-release properties with peak concentrations at ~1.5-2 hours. |
| Duration of Action | Duration of anxiolytic effect is approximately 24 hours with once-daily dosing. Steady-state is achieved within 2-3 days. |
0.5-1 mg orally once daily; may increase at 3-4 day intervals; maximum 10 mg/day
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR 30-89 mL/min: no adjustment; GFR 15-29 mL/min: initiate at 0.5 mg once daily, titrate cautiously; GFR <15 mL/min: avoid use |
| Liver impairment | Child-Pugh Class A: initiate 0.5 mg once daily; Child-Pugh Class B: initiate 0.25 mg once daily; Child-Pugh Class C: avoid use |
| Pediatric use | Not FDA approved for patients <18 years; off-label doses: 0.125-0.5 mg/kg/day divided once daily; titrate slowly |
| Geriatric use | Initiate 0.25 mg once daily; titrate by 0.125 mg increments every 3-4 days; maximum 2 mg/day |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for XANAX XR (XANAX XR).
| Breastfeeding | Alprazolam is excreted in breast milk. M/P ratio approximately 0.36. Monitor infant for sedation, poor feeding, and weight gain. Use lowest effective dose and consider alternative agents if prolonged use required. |
| Teratogenic Risk | First trimester: Increased risk of oral cleft (absolute risk 0.5-1% vs 0.1-0.2% background). Second and third trimesters: Risk of floppy infant syndrome, withdrawal symptoms, respiratory depression, and neonatal sedation. Late third trimester or delivery: Risk of neonatal withdrawal and hypotonia. |
■ FDA Black Box Warning
Concomitant use with opioids may result in profound sedation, respiratory depression, coma, and death; reserve for patients with inadequate alternative treatment options.
| Serious Effects |
["Hypersensitivity to alprazolam or other benzodiazepines","Concurrent use with ketoconazole or itraconazole","Acute narrow-angle glaucoma"]
| Precautions | ["Risks of dependence and withdrawal reactions","Risk of abuse and misuse","Concomitant use with CNS depressants","Risk of severe anaphylactic reactions","Use in patients with depression or suicidal ideation"] |
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| Fetal Monitoring |
| Monitor maternal sedation, respiratory rate, and CNS depression. Fetal monitoring for growth restriction and preterm labor. Assess neonatal Apgar scores, respiratory effort, and signs of withdrawal or sedation after delivery. |
| Fertility Effects | May cause menstrual irregularities, anovulation, and decreased libido due to CNS depression and potential hyperprolactinemia. Reversible upon discontinuation. |