Alprazolam
8-chloro-1-methyl-6-phenyl-4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepine
Overview
Alprazolam belongs to Depressants / Benzodiazepines.
Effects
Subjective effects vary. What a substance feels like depends on dose, individual physiology,
mindset, and setting. The points below describe commonly reported effects, not guaranteed, uniform, or
desirable outcomes.
- Rapid relief of anxiety, a sense of calm and muscle relaxation, with drowsiness and sedation.
- At higher or recreational doses: euphoria, disinhibition and anterograde amnesia ('blackouts'), with actions not remembered afterwards.
- Because it is short-acting, anxiety and restlessness often rebound between doses.
- Marked next-day sedation and psychomotor/cognitive impairment. Paradoxical agitation, irritability or aggression in some people.
Dosing & duration
Harm-reduction note: These are commonly cited reference ranges, not a recommendation or a
“safe” dose. Potency, purity, body chemistry, tolerance, and drug combinations vary widely. Start
low, go slow, wait for full effects before redosing, and never assume an unknown product matches these
figures. Missing data is not evidence of safety.
Oral. These are therapeutic ranges for a prescription medicine, not recreational guidance. Alprazolam is high-potency: a '1 mg' tablet is already a substantial dose and the 2 mg 'bar' is a large amount. It should be used only as prescribed, individualised and tapered under medical supervision, and never stopped abruptly. Never combine it with opioids, alcohol or other depressants (additive respiratory depression). Illicit tablets are frequently counterfeit and may contain fentanyl or designer benzodiazepines.
Dose ranges
Anxiety (therapeutic)
≈0.25–0.5 mg, 2–3×/day
Panic disorder (specialist)
titrated, often ~1–4 mg/day
'Bar' (single pressed tablet)
2 mg: a large dose
Duration
onset
≈15–30 min
peak
≈1–2 h
total
≈5–6 h (short-acting, half-life 11–16 h)
Chemical & Physical Properties
| Formula | C17H13ClN4 |
| Molar mass | 308.76 g/mol |
| State | Solid |
| Melting point | 228–229.5 °C |
| Boiling point | Not reported |
| Density | Not reported |
| Vapor pressure | Not reported |
| pKa | Not reported |
| LogP | 2.12 |
| Solubility | Insoluble in water, Freely soluble in chloroform, soluble in alcohol. Sparingly soluble in acetone. Solubility soluble in ethyl acetate, 3.24×10⁻² g/L |
| Refractive index | Not reported |
Identifiers & Synonyms
| CAS | 28981-97-7 |
| CAS (enantiomer) | |
| PubChem CID | 2118 |
| InChIKey | VREFGVBLTWBCJP-UHFFFAOYSA-N |
| InChI | InChI=1S/C17H13ClN4/c1-11-20-21-16-10-19-17(12-5-3-2-4-6-12)14-9-13(18)7-8-15(14)22(11)16/h2-9H,10H2,1H3 |
| SMILES | CC1=NN=C2N1C3=C(C=C(C=C3)Cl)C(=NC2)C4=CC=CC=C4 |
Synonyms
- Xanax
- Alprazolam
- Tafil
- Niravam
- Xanor
- Bars
Pharmacodynamics & Biochemistry
Alprazolam is a high-potency triazolobenzodiazepine. It is a positive allosteric modulator at the benzodiazepine site of the GABA-A receptor: it does not open the chloride channel itself but increases the frequency of channel opening in response to GABA, enhancing inhibitory neurotransmission throughout the CNS. This produces its anxiolytic, sedative-hypnotic, muscle-relaxant and anticonvulsant effects. It binds the classical benzodiazepine-sensitive GABA-A subtypes (α1/α2/α3/α5-containing receptors) with comparable, nanomolar potency. α1-rich receptors mediate sedation while α2/α3 mediate anxiolysis. Its fused triazole ring makes it more potent and shorter-acting than older benzodiazepines, which underlies both its rapid anti-panic action and its marked inter-dose rebound and withdrawal.
Biological targets
- GABA-A
Binding & functional measurements
| Target | Measurement | Species |
|---|---|---|
| GABAA receptor α5 subunit | pEC50 8 | Human |
| GABAA receptor α2 subunit | pEC50 7.9 | Human |
| GABA-A α1β2γ2 receptor | EC50 15 nM | Human |
| GABAA receptor α3 subunit | pEC50 7.2 | Human |
| GABA-A α1β2γ2 receptor | EC50 57 ± 15 nM Emax 171 ± 12% | Rat |
| GABA-A α2β3γ2 receptor | EC50 34 ± 13 nM Emax 231 ± 14% | Rat |
| GABA-A α3β3γ2 receptor | EC50 472 ± 19 nM Emax 495 ± 105% | Rat |
| GABA-A α5β3γ2 receptor | EC50 89 ± 22 nM Emax 182 ± 52% | Rat |
Pharmacokinetics
| Bioavailability | Oral ≈80–90% |
| Tmax | ≈1–2 h |
| Half-life | ≈11–16 h |
| Vd | Not reported |
| Protein binding | ≈80% |
| Metabolism | Hepatic CYP3A4 to alpha-hydroxyalprazolam |
| Excretion | Renal |
Toxicology & Safety
Harm-reduction note: Toxicity and risk depend on dose, route, purity, combinations, setting, and individual
health factors. Missing harms should never be interpreted as evidence of safety.
Not reported
Alprazolam is a high-potency, relatively short-acting triazolobenzodiazepine with a pronounced potential for tolerance, dependence and misuse. Its short duration causes inter-dose rebound anxiety, and on stopping after regular use it produces a benzodiazepine withdrawal syndrome that can be severe and, with abrupt discontinuation, life-threatening (seizures, delirium). It must be tapered slowly under medical supervision and never stopped suddenly. The greatest acute danger is additive respiratory depression when combined with opioids (an FDA boxed warning), alcohol or other CNS depressants: a leading contributor to benzodiazepine overdose deaths. It causes sedation, anterograde amnesia and next-day psychomotor/cognitive impairment (falls in the elderly, impaired driving), and can cause paradoxical agitation. A specific street-market hazard: illicit pressed 'Xanax bars' are frequently counterfeit and contain fentanyl or novel designer benzodiazepines (e.g. bromazolam, etizolam) rather than alprazolam, greatly raising overdose risk: non-pharmacy tablets must never be trusted. Use in pregnancy carries fetal and neonatal risks.[3][4]
Legal Status
Legal note: Legal status can change over time and may vary by country, region, formulation, analogue status,
prescription context, and enforcement practice. Always confirm with current official sources before relying on this section.
US: Schedule IV. UK: Class C. DE: BtMG Anlage III (Rx)
Interactions & Contraindications
Drug interactions
Opioids, Alcohol, Benzodiazepines, Gabapentinoids (gabapentin, pregabalin) Profound additive sedation and respiratory depression: the main cause of benzodiazepine overdose deaths (FDA boxed warning for opioids), including with sedating antihistamines.[4]
CYP3A4 inhibitors (ritonavir, azole antifungals, macrolides, grapefruit) Azole antifungals, ritonavir, clarithromycin or grapefruit markedly raise alprazolam levels and effect.[4]
CYP3A4 inducers (rifampicin, carbamazepine) Carbamazepine, rifampicin or St John's wort lower levels and may precipitate withdrawal.[4]
Contraindications
Combining with alcohol or other CNS depressants concurrent opioids or other CNS depressants without close supervision (respiratory-depression risk).[4]
Closed-angle glaucoma acute narrow-angle glaucoma.[4]
Respiratory disease or sleep apnoea severe respiratory insufficiency or sleep apnoea.[4]
Myasthenia gravis[4]
Concurrent strong CYP3A4 inhibitor (ketoconazole, itraconazole, ritonavir) concurrent strong CYP3A4 inhibitors (e.g. ketoconazole, itraconazole).[4]
Pregnancy or breastfeeding[4]
No interactions or contraindications listed.
Usage & Context
- A widely prescribed benzodiazepine (Xanax) for anxiety and panic disorder, and one of the most commonly misused and diverted benzodiazepines.
- Illicitly sold as pressed 'bars' (nominally 2 mg tablets), frequently counterfeit and contaminated with fentanyl or novel designer benzodiazepines.
Sources & Evidence
- PubChem: Alprazolam (CID 2118) — identifiers & computed properties
- IUPHAR/BPS Guide to PHARMACOLOGY: alprazolam (ligand 7111) — GABA-A subunit activity CC BY-SA 4.0
- Verster JC, Volkerts ER (2004). Clinical pharmacology, clinical efficacy, and behavioral toxicity of alprazolam: a review of the literature. CNS Drug Rev 10:45-76.
PMID 14978513 · doi:10.1111/j.1527-3458.2004.tb00003.x
- FDA / DailyMed: Alprazolam prescribing information — boxed warning (opioids, abuse/dependence, withdrawal)
- DEA Diversion Control Division: Controlled Substance Schedules (alprazolam — Schedule IV)
- BtMG Anlage III — Betäubungsmittelgesetz (alprazolam, preparations ≤1 mg/unit exempt, normal prescription)
- Albaugh PA, Marshall L, Gregory J, et al. (2002). Synthesis and biological evaluation of 7,8,9,10-tetrahydroimidazo[1,2-c]pyrido[3,4-e]pyrimdin-5(6H)-ones as functionally selective ligands of the benzodiazepine receptor site on the GABA(A) receptor. J Med Chem 45:5043-51.
PMID 12408715 · doi:10.1021/jm0202019
- Norman C, Liin SI, Jauregi-Miguel A, Ottosson NE, Gréen H (2026). In vitro γ-aminobutyric acid A (GABAA) receptor activity and binding interactions at the α+/γ2− interface of 53 prescription and designer benzodiazepines. Commun Chem 9:155.
PMID 41946818 · doi:10.1038/s42004-026-02001-x
- Masneuf S, Buetler J, Koester C, Crestani F (2012). Role of α1- and α2-GABA(A) receptors in mediating the respiratory changes associated with benzodiazepine sedation. Br J Pharmacol 166:339-48.
PMID 22044283 · doi:10.1111/j.1476-5381.2011.01763.x