ALPRAZOLAM
Clinical safety rating: avoid
Positive evidence of fetus risks but benefits may outweigh risks in some cases
Positive allosteric modulator of GABA-A receptors; enhances GABA inhibitory neurotransmission by binding to benzodiazepine site on GABA-A receptor, increasing chloride ion conductance.
| Metabolism | Primarily hepatic via CYP3A4; major metabolites are alpha-hydroxyalprazolam (active) and 4-hydroxyalprazolam (inactive). |
| Excretion | Renal (approximately 80% as metabolites, <20% unchanged); fecal (minor, ~7%) |
| Half-life | 12-15 hours (mean ~13 hours); prolonged in elderly (up to 19 hours) and hepatic impairment (up to 20-30 hours); clinical context: allows once- to twice-daily dosing, but risk of accumulation with high doses or in vulnerable populations |
| Protein binding | 80% (primarily to albumin, minor to α1-acid glycoprotein) |
| Volume of Distribution | 0.8 L/kg (range 0.6-1.2 L/kg); clinical meaning: moderate tissue distribution, reflects lipophilicity; higher Vd in obesity |
| Bioavailability | Oral: 90% (immediate-release); extended-release: approximately 90% relative to immediate-release; sublingual: approximately 75-80% of oral |
| Onset of Action | Oral: 15-30 minutes (immediate-release), 0.5-2 hours (extended-release); sublingual: 10-15 minutes; clinical effect: anxiolysis within 30-60 minutes |
| Duration of Action | 4-6 hours (immediate-release); up to 24 hours (extended-release); clinical note: anxiolytic effect may persist beyond sedation; rebound anxiety can occur with short-acting formulations |
| Molecular Weight | 308.77 |
0.25-0.5 mg orally 3 times daily; maximum 4 mg/day in divided doses.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR 10-50 mL/min: reduce dose by 50%; GFR <10 mL/min: use with caution, reduce dose by 50% or consider alternative. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use. |
| Pediatric use | Not FDA-approved for <18 years; limited data: 0.125 mg/kg/dose orally 3 times daily (max 0.02 mg/kg/dose) for panic disorder in adolescents. |
| Geriatric use | Start with 0.25 mg orally 2-3 times daily; increase slowly due to increased sensitivity and risk of falls; maximum 2 mg/day. |
| 1st trimester | Associated with increased risk of cleft palate; use only if benefit outweighs risk. |
| 2nd trimester | May cause fetal benzodiazepine exposure; limited data suggest possible subtle neurodevelopmental effects. |
| 3rd trimester | Risk of neonatal withdrawal syndrome and floppy infant syndrome; avoid near term. |
Clinical note
Strong CYP3A4 inhibitors like ketoconazole can significantly increase levels Risk of profound sedation respiratory depression and coma if used with opioids or alcohol Abrupt discontinuation can cause seizures.
| Placental transfer | Crosses placenta readily; fetal concentrations may equal maternal. |
| Breastfeeding | Minimal excretion into breast milk; low relative infant dose. Monitor infant for sedation and weight gain. Caution in long-term use. |
■ FDA Black Box Warning
Concomitant use of benzodiazepines and opioids may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for patients for whom alternative treatment options are inadequate.
| Common Effects | panic disorder |
| Serious Effects |
Acute narrow-angle glaucomaConcurrent use with ketoconazole or itraconazoleSevere hepatic impairmentKnown hypersensitivity to benzodiazepines
| Precautions | Risk of abuse, misuse, and addiction; dependence and withdrawal reactions; respiratory depression; worsening of depression or suicidal ideation; use in patients with acute narrow-angle glaucoma; impaired motor and cognitive performance; risk of severe allergic reactions. |
| Food/Dietary | Avoid grapefruit and grapefruit juice as they inhibit CYP3A4 metabolism, increasing alprazolam levels and risk of toxicity. Avoid alcohol. No other significant food interactions. |
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| Lactation Rating |
| L2 (Safer) |
| Teratogenic Risk | First trimester: Associated with increased risk of cleft lip/palate (OR 2.0); avoid if possible. Second/third trimester: Risk of benzodiazepine withdrawal or floppy infant syndrome (hypotonia, respiratory depression, feeding difficulties) with chronic high-dose use. Late third trimester: Risk of neonatal withdrawal syndrome. |
| Fetal Monitoring | Monitor for maternal sedation, respiratory depression, and signs of dependence. In fetus: serial ultrasound for growth restriction if long-term use. Neonatal monitoring for hypotonia, respiratory distress, poor feeding, and withdrawal symptoms (irritability, tremors) for 48-72 hours postpartum. |
| Fertility Effects | No definitive evidence of impaired fertility in humans. Animal studies show no significant effects. Benzodiazepines may alter menstrual cycle or libido, but clinical significance unclear. |
| Clinical Pearls | Alprazolam is a short-acting benzodiazepine with a rapid onset. Due to its high potency and short half-life, it carries a high risk of dependence and withdrawal. Avoid in patients with narrow-angle glaucoma, severe respiratory insufficiency, or myasthenia gravis. Use with caution in patients with history of substance abuse. Taper gradually to prevent rebound anxiety and seizures. Onset of action is 15-30 min orally; peak effect at 1-2 hours. |
| Patient Advice | Take exactly as prescribed; do not increase dose or frequency without consulting your doctor. · Avoid alcohol and other central nervous system depressants as they can cause severe sedation and respiratory depression. · Do not drive or operate heavy machinery until you know how alprazolam affects you; it may cause drowsiness or dizziness. · Do not stop abruptly; withdrawal symptoms can include anxiety, insomnia, seizures, and life-threatening reactions. · Store at room temperature away from moisture and heat. Keep out of reach of children. · Inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding. · Report any worsening of depression or suicidal thoughts immediately. |