Alprazolam — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	PO	0.01-0.1 mg/kg (anxiety); 0.02-0.04 mg/kg (sedation)	q8-12h as needed or scheduled	Duration: Short-term (days to weeks); use lowest effective dose Notes: Titrate to effect; may cause paradoxical excitation in some dogs.
Cat	PO	0.0125-0.05 mg/kg (anxiety); 0.05-0.1 mg/kg (sedation)	q12-24h as needed	Duration: Short-term; use with caution in hepatic disease Notes: Cats may be more sensitive; start low and titrate.
Horse	PO	0.02-0.04 mg/kg	q12h as needed	Duration: Short-term Notes: Limited data; use with caution.
Rabbit	PO	0.1-0.5 mg/kg	q12-24h	Duration: Short-term Notes: Limited data; monitor for sedation.

Clinical Indications & Species Uses

General Indications

Anxiety and phobias
Sedation
Muscle relaxation

Dog (Canine)

Anxiety disorders (separation anxiety, noise phobias, situational anxiety)
Adjunct in behavioral therapy
Short-term sedation
Anticonvulsant (adjunctive)

Cat (Feline)

Anxiety disorders (fear, aggression, inappropriate urination)
Short-term sedation
Appetite stimulant (off-label)

Horse (Equine)

Anxiolytic for handling and transport
Sedative (off-label)

Rabbit & Small Mammals

Anxiolytic (off-label)
Sedative (off-label)

Exotic & Other Species

Anxiolytic in some exotic species (off-label)

Pharmacology & Mechanism of Action

Drug Class: Benzodiazepine | Pharmacological Group: Anxiolytic, Sedative-Hypnotic

Mechanism of Action: Alprazolam is a benzodiazepine that binds to the benzodiazepine site on the gamma-aminobutyric acid type A (GABA-A) receptor complex, enhancing the inhibitory effects of GABA. This increases the frequency of chloride channel opening, leading to hyperpolarization of neurons and reduced neuronal excitability. The result is anxiolytic, sedative, muscle relaxant, and anticonvulsant effects.

Pharmacodynamics: Alprazolam produces dose-dependent central nervous system depression. At therapeutic doses, it reduces anxiety and aggression, and may cause mild sedation. It has rapid onset of action. In dogs, it may also have some antiemetic effects. Chronic use can lead to tolerance and physical dependence.

⚡ Pharmacokinetics Summary

Absorption: Rapidly absorbed after oral administration. Peak plasma concentrations occur within 1-2 hours in dogs and cats. Bioavailability is high (approximately 80-90%).

Distribution: Widely distributed throughout the body. Crosses the blood-brain barrier and placenta. Volume of distribution is moderate. Protein binding is approximately 70-80%.

Metabolism: Extensively metabolized in the liver, primarily by cytochrome P450 enzymes (CYP3A4). Major metabolites include alpha-hydroxyalprazolam and 4-hydroxyalprazolam, which are pharmacologically active but less potent than the parent drug.

Excretion: Excreted primarily in urine as metabolites, with a small amount as unchanged drug. Fecal excretion is minor. In dogs, the elimination half-life is approximately 2-4 hours; in cats, it is longer, around 5-8 hours.

Half-Life: Dog: 2-4 hours; Cat: 5-8 hours; Horse: 1-2 hours (estimated)

Bioavailability: High (80-90%) after oral administration

Protein Binding: 70-80%

Available Formulations & Strengths

Oral Tablet 0.25 mg, 0.5 mg, 1 mg, 2 mg (PO)

Oral Solution 1 mg/mL (PO)

Injectable Solution (not commonly used in veterinary medicine) 1 mg/mL (for IV/IM use) (IV/IM)

Contraindications & Clinical Warnings

Contraindications:

Hypersensitivity to alprazolam or other benzodiazepines
Severe hepatic insufficiency
Acute narrow-angle glaucoma
Concurrent use with strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole) without dose adjustment
Use in animals with myasthenia gravis

Warnings & Clinical Precautions:

Use with caution in animals with hepatic or renal disease
May cause paradoxical excitation or aggression, especially in dogs and cats
Can cause physical and psychological dependence with prolonged use; avoid abrupt discontinuation
Use with caution in pregnant or lactating animals; safety not established
May cause sedation and ataxia; monitor when used in working animals
In horses, may cause ataxia and incoordination; avoid use in performance horses during competition

Adverse Effects & Reactions

Common:

Sedation
Ataxia
Increased appetite
Paradoxical excitation or aggression

Serious / Severe:

Respiratory depression (especially with overdose or concurrent CNS depressants)
Hepatic toxicity (rare)
Dependence and withdrawal syndrome

Rare:

Blood dyscrasias
Hypotension
Skin reactions

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Other CNS depressants (opioids, barbiturates, phenothiazines)	Additive sedation and respiratory depression	High
CYP3A4 inhibitors (ketoconazole, itraconazole, erythromycin)	Increased alprazolam plasma concentrations and toxicity	High
CYP3A4 inducers (phenobarbital, rifampin)	Decreased alprazolam efficacy	Moderate
Cimetidine	Increased alprazolam levels	Moderate
Digoxin	Increased digoxin levels (rare)	Mild

Overdose & Toxicity Management

Signs of Toxicity:

Severe sedation
Ataxia
Coma
Respiratory depression
Hypotension
Paradoxical excitation (in some animals)

Emergency Treatment Protocol: Supportive care; induce vomiting if recent ingestion and animal is conscious; administer activated charcoal; provide respiratory support if needed; flumazenil (benzodiazepine antagonist) may be used (0.01-0.02 mg/kg IV) but use with caution as it may precipitate seizures in animals with benzodiazepine tolerance.

Food Animal Withdrawal Times

Not approved for food animals; extra-label use in food animals is prohibited in the US. No withdrawal times established.

Storage, Handling & Regulatory Information

Storage Temperature: Store at room temperature (20-25°C)

Handling & Special Conditions: Protect from moisture; keep in tight container.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use; approved for human use.

Extra-Label (Off-Label) Use: In the US, alprazolam is not FDA-approved for veterinary use; extra-label use is permitted under AMDUCA for non-food animals only. Use in food animals is prohibited.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Alprazolam is a short-acting benzodiazepine used primarily for anxiety and phobias in dogs and cats. It has a rapid onset and is useful for situational anxiety (e.g., thunderstorms, fireworks). It may be used as an adjunct to behavioral modification. Due to its short half-life, it may require multiple daily doses. Tolerance can develop with chronic use; therefore, it is best used intermittently or as needed. In cats, it may stimulate appetite. Caution is advised in animals with hepatic disease. Abrupt discontinuation after prolonged use can cause withdrawal signs; taper the dose gradually. Always use the lowest effective dose for the shortest duration.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)