Oxazepam
Oxazepam is a short-to-intermediate-acting **benzodiazepine** primarily utilized in veterinary medicine as an **appetite stimulant** and **anxiolytic** in dogs and cats. **Clinical Pearls & Pharmacologic Advantages:** * **Metabolic Profile:** Unlike diazepam, oxazepam does not undergo Phase I hepatic metabolism (oxidation) and lacks active metabolites. It is metabolized solely via Phase II glucuronidation. * **Geriatric & Hepatic Safety:** Because of its simpler metabolic pathway, it is often considered a safer alternative to diazepam for geriatric patients or those with mild-to-moderate liver dysfunction. * **Feline Considerations:** Despite its favorable metabolic profile, its use in cats with hepatic lipidosis or severe liver dysfunction remains controversial due to rare, anecdotal reports of idiosyncratic fulminant hepatic failure. * **Behavioral Use:** It is used as an adjunctive oral anxiolytic for fears, phobias, and urine marking, though paradoxical excitation can occasionally occur.
Mecanismo: Oxazepam acts as a positive allosteric modulator at the **GABA-A receptor** complex in the central nervous system. * **Binding:** It binds to specific benzodiazepine recognition sites on the **GABA-A** ligand-gated chloride channel. * **Mechanism:** It enhances the inhibitory effect of **gamma-aminobutyric acid (GABA)** by increasing the *frequency* of chloride channel openings. * **Pathway:** Influx of chloride ions → **neuronal hyperpolarization** → decreased neuronal excitability. * **Clinical Effect:** This depression of subcortical CNS levels (primarily limbic, thalamic, and hypothalamic) produces the characteristic anxiolytic, sedative, skeletal muscle relaxant, and anticonvulsant effects.
Dosificación por especie
- Appetite stimulant · 2 mg per cat (total dose) · PO · every 12 hours
- Appetite stimulant (hepatic lipidosis) · 0.1-0.3 mg/kg · PO · q12-24h · If cat has a small interest in eating
- Appetite stimulant · 0.25-0.5 mg/kg · PO · one to two times daily
- Fears and phobias · 1-2.5 mg per cat (total dose) · PO · every 12 hours
- Fears and phobias · 0.2-0.5 mg/kg · PO · q12-24h
- Feline urine marking · 0.2-0.5 mg/kg · PO · once to twice a day
- Spraying or overgrooming · 0.2-0.5 mg/kg · PO · q12-24h
- Fears and phobias · 0.2-1 mg/kg · PO · q12h or q6h · The lowest dose and longest frequency between doses that alleviate the fear should be used.
- Fears and phobias · 0.2-0.5 mg/kg · PO · q12-24h
- Fears and phobias · 0.2-1 mg/kg · PO · q12-24h
- Fears and phobias · 0.2-1 mg/kg · PO · one to two times a day
- Fears and phobias · 0.04-0.5 mg/kg · PO · q6h · The lowest dose and longest frequency between doses that alleviate the fear should be used.
Vías de administración
Contraindicaciones
- Known benzodiazepine hypersensitivity
- Acute narrow angle glaucoma
Efectos adversos
- Sedation (most common)
- Ataxia
- Paradoxical excitability, vocalization, or aggression
- Rebound anxiety or behavior worsening (if withdrawn abruptly)
- Rare precipitation of tonic-clonic seizures
- Rare idiosyncratic fulminant hepatic failure (cats)
Interacciones farmacológicas
- CNS Depressant Drugs (barbiturates, narcotics, anesthetics) · Additive CNS depression effects may occur.
- Phenytoin · May decrease oxazepam concentrations.
- Probenecid · May impair glucuronide conjugation (in dogs) and prolong effects.
- Rifampin · May induce hepatic microsomal enzymes and decrease the pharmacologic effects of benzodiazepines.
- St. John's Wort · May decrease oxazepam effectiveness.
- Theophyllines · May decrease oxazepam effectiveness.
Monitorización
- Clinical efficacy (improved appetite, reduced anxiety/fear)
- Adverse effects (degree of sedation, ataxia, paradoxical excitement)
Sobredosis
**Signs of Toxicity:** When used alone, overdoses are generally limited to significant CNS depression (confusion, coma, decreased reflexes, profound sedation). **Treatment:** * **Decontamination:** Standard protocols for removing and/or binding the drug in the gut (e.g., emesis induction if asymptomatic and recent, activated charcoal) if taken orally. * **Supportive Care:** Systemic supportive measures (IV fluids, warming, respiratory support if needed). * **Antidote:** **Flumazenil** (a specific benzodiazepine antagonist) could potentially be used in life-threatening overdoses. * **Contraindications:** The use of analeptic agents (CNS stimulants such as caffeine, amphetamines) is generally not recommended.
La referencia de fármacos de VetSheet está destinada a veterinarios colegiados como apoyo a la decisión clínica, no sustituye el juicio profesional ni la ficha técnica vigente del fabricante.