Oxazepam — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	PO	0.2-1.0 mg/kg	q8-12h	Duration: As needed or for 2-4 weeks for anxiety; short-term use recommended Notes: Start at low end and titrate to effect. Use with caution in patients with hepatic disease.
Cat	PO	0.2-0.5 mg/kg (appetite stimulation: 0.5-1.0 mg/kg)	q12-24h	Duration: Short-term; for appetite stimulation, give 30-60 minutes before feeding Notes: May cause paradoxical excitement in some cats. Monitor for sedation.
Horse	PO	0.5-1.0 mg/kg	q12h	Duration: Short-term Notes: Not commonly used; IV diazepam or midazolam preferred for sedation.
Rabbit	PO	0.5-2.0 mg/kg	q8-12h	Duration: Short-term Notes: Limited data; use with caution.

Clinical Indications & Species Uses

General Indications

Anxiolytic
Sedative
Appetite stimulant (in cats)

Dog (Canine)

Anxiety disorders (separation anxiety, noise phobias)
Situational anxiety (e.g., veterinary visits, grooming)
Appetite stimulation (less common)
As an adjunct in behavioral therapy

Cat (Feline)

Appetite stimulation (especially in hospitalized or stressed cats)
Anxiety reduction (e.g., during travel or veterinary visits)
Urine spraying (off-label)
Aggression (off-label)

Horse (Equine)

Sedation (less common, other benzodiazepines preferred)
Anxiety reduction (off-label)

Rabbit & Small Mammals

Anxiolytic (off-label, limited data)

Pharmacology & Mechanism of Action

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

Mechanism of Action: Oxazepam is a benzodiazepine that binds to the benzodiazepine site on the gamma-aminobutyric acid type A (GABA-A) receptor, a ligand-gated chloride channel. This binding enhances the affinity of GABA for its receptor, increasing the frequency of chloride channel opening and resulting in hyperpolarization of the neuron. This leads to inhibitory effects on the central nervous system, producing anxiolytic, sedative, muscle relaxant, and anticonvulsant effects. Oxazepam is an active metabolite of diazepam and has a slower onset but similar efficacy.

Pharmacodynamics: Oxazepam produces dose-dependent depression of the central nervous system. At therapeutic doses, it reduces anxiety, aggression, and fear-related behaviors. It also has muscle relaxant and anticonvulsant properties. In veterinary medicine, it is used primarily for its anxiolytic effects, especially in cats for appetite stimulation and in dogs for situational anxiety. Its effects are mediated through the limbic system, thalamus, and hypothalamus. Tolerance and dependence can develop with prolonged use.

⚡ Pharmacokinetics Summary

Absorption: Oxazepam is well absorbed after oral administration, with peak plasma concentrations occurring within 1-2 hours in most species. Food may delay absorption but does not significantly affect the extent.

Distribution: Oxazepam is highly lipophilic and distributes widely throughout the body, including the brain. It crosses the blood-brain barrier and placenta, and is distributed into milk. Protein binding is approximately 86-97% in humans, but may vary in animals.

Metabolism: Oxazepam is primarily metabolized in the liver via glucuronide conjugation to inactive metabolites. Unlike many other benzodiazepines, it does not undergo oxidative metabolism, so it is less affected by hepatic enzyme inducers or inhibitors. This makes it a safer choice in patients with liver disease.

Excretion: Oxazepam and its glucuronide metabolites are excreted primarily in the urine. The elimination half-life is relatively short compared to other benzodiazepines, ranging from 5-15 hours in dogs and cats, but may be longer in some individuals.

Half-Life: Dogs: 5-10 hours; Cats: 5-15 hours; Horses: 2-4 hours (estimated); Humans: 5-15 hours

Bioavailability: Oral bioavailability is approximately 90% in dogs and cats (estimated).

Protein Binding: Approximately 86-97% (species-dependent)

Available Formulations & Strengths

Oral Tablet 10 mg, 15 mg, 30 mg (PO)

Oral Capsule 10 mg, 15 mg, 30 mg (PO)

Contraindications & Clinical Warnings

Contraindications:

Hypersensitivity to oxazepam or other benzodiazepines
Severe hepatic insufficiency
Acute narrow-angle glaucoma
Myasthenia gravis
Severe respiratory insufficiency
Use in pregnant or lactating animals unless benefits outweigh risks (especially during first trimester)

Warnings & Clinical Precautions:

Use with caution in patients with renal or hepatic impairment; dose adjustment may be necessary.
May cause physical and psychological dependence with prolonged use; avoid abrupt discontinuation.
Paradoxical reactions (excitement, aggression) may occur, especially in cats and some dogs.
Use with caution in debilitated or geriatric animals due to increased risk of sedation and ataxia.
May impair coordination and cognitive function; avoid use in working animals.
Not recommended for use in animals with a history of substance abuse (rare in veterinary medicine).
In food animals, extra-label use is prohibited in the US; check regulations.

Adverse Effects & Reactions

Common:

Sedation
Ataxia
Increased appetite (especially in cats)
Paradoxical excitement or aggression
Muscle weakness

Serious / Severe:

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

Rare:

Hypotension
Gastrointestinal disturbances (vomiting, diarrhea)
Skin reactions
Jaundice

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Other CNS depressants (e.g., opioids, barbiturates, phenothiazines)	Additive sedation and respiratory depression	High
Cimetidine	May increase oxazepam levels (though less than other benzodiazepines)	Moderate
Fluoxetine or other SSRIs	May increase risk of serotonin syndrome or excessive sedation	Moderate
Ketoconazole or other CYP3A4 inhibitors	May increase oxazepam levels (though oxazepam is less dependent on CYP450)	Mild
Rifampin or other CYP3A4 inducers	May decrease oxazepam levels	Mild

Overdose & Toxicity Management

Signs of Toxicity:

Severe sedation
Ataxia
Coma
Respiratory depression
Hypotension
Hypothermia
Paradoxical excitation (especially in cats)

Emergency Treatment Protocol: Treatment is primarily supportive. Induce vomiting if recent ingestion and animal is conscious. Administer activated charcoal to reduce absorption. Provide respiratory support (oxygen, ventilation) if needed. Flumazenil (benzodiazepine antagonist) can be administered at 0.01-0.02 mg/kg IV, but use with caution as it may precipitate seizures in animals with benzodiazepine dependence. Monitor vital signs and provide fluid therapy for hypotension.

Food Animal Withdrawal Times

Oxazepam is not approved for use in food animals in the US. Extra-label use in food animals is prohibited. No withdrawal times are established.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature (20-25°C, excursions permitted to 15-30°C)

Light Sensitivity: Light-sensitive — protect from direct exposure.

Handling & Special Conditions: Protect from light and moisture. Keep in a tightly closed container.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not approved for veterinary use in the US; used extra-label in companion animals.

Extra-Label (Off-Label) Use: In the US, extra-label use of oxazepam in food animals is prohibited by the FDA (AMDUCA). In companion animals, extra-label use is permitted under veterinary supervision.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Oxazepam is a benzodiazepine with a relatively short half-life and no active metabolites, making it a safer choice for patients with hepatic disease compared to diazepam. In veterinary medicine, it is primarily used for anxiety and appetite stimulation in cats. It is a controlled substance (Schedule IV) and should be used with caution due to potential for dependence and withdrawal. Doses should be titrated to the lowest effective dose. For cats, it can be particularly useful for stimulating appetite in hospitalized or stressed animals; however, some cats may exhibit paradoxical excitement. Always monitor for excessive sedation and respiratory depression, especially when used with other CNS depressants. In food animals, use is prohibited; in performance animals, check withdrawal times and regulations. Store in a cool, dry place and protect from light.

References & Literature

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