Chlordiazepoxide and Clidinium
Chlordiazepoxide is a long-acting **benzodiazepine** primarily used for its anxiolytic and mild sedative properties. Clidinium bromide is a synthetic quaternary ammonium **antimuscarinic (anticholinergic)** agent that reduces gastrointestinal motility and spasms. In veterinary medicine, these drugs are occasionally used alone or in combination: * **Chlordiazepoxide alone**: Used as an adjunct for behavioral disorders, such as noise phobias in dogs, or intercat aggression and urine spraying in cats. * **Chlordiazepoxide + Clidinium (Librax®)**: This combination is uniquely positioned to treat stress-induced gastrointestinal disorders, such as **Irritable Bowel Syndrome (IBS)** in dogs. It addresses both the central anxiety component (via chlordiazepoxide) and the peripheral GI spasms (via clidinium). > **Clinical Pearl**: Because clidinium is a quaternary amine, it does not readily cross the blood-brain barrier, thereby avoiding the central anticholinergic side effects commonly seen with atropine.
Mecanismo: The combination product exerts its effects through two distinct mechanisms targeting the central nervous system and the peripheral gastrointestinal tract: * **Chlordiazepoxide (Anxiolytic/Sedative)**: Binds to the benzodiazepine allosteric site on the **GABA-A receptor** complex in the CNS → enhances the affinity of the receptor for the inhibitory neurotransmitter **gamma-aminobutyric acid (GABA)** → increases the frequency of chloride channel openings → neuronal hyperpolarization. This dampens activity in the limbic system, thalamus, and hypothalamus, producing anxiolytic, muscle relaxant, and anticonvulsant effects. * **Clidinium (Antispasmodic)**: Acts as a competitive antagonist at **muscarinic acetylcholine receptors** (primarily M3 receptors in the gut) → inhibits parasympathetic nerve impulses → significantly reduces gastrointestinal smooth muscle spasms, motility, and gastric acid secretion.
Dosificación por especie
- As an anxiolytic · 0.5-1 mg/kg · PO · q12-24h · Chlordiazepoxide alone
- Behavior indications (thunderstorm/noise phobias) · 2.2-6.6 mg/kg · PO · as needed · Chlordiazepoxide alone; start low
- Symptomatic treatment of irritable bowel syndrome · 0.1-0.25 mg/kg of clidinium or 1-2 capsules · PO · two times to three times a day · Discontinued in a few days · Using the combination product (e.g., Librax). Give when abdominal pain or diarrhea first noticed or if stressful conditions are encountered.
- Symptomatic treatment of irritable bowel syndrome · 0.44-1.1 mg/kg of clidinium · PO · two to three times a day · 1 day to 2 weeks (some require long-term treatment at 1-2 doses per day) · Using the combination product (e.g., Librax). Use at first signs of cramping or abdominal pain.
Las dosis son una referencia clínica para veterinarios colegiados. Confirme siempre con la ficha técnica vigente y el paciente individual.
Vías de administración
Contraindicaciones
- Known hypersensitivity to benzodiazepines or antimuscarinics
- Coma, shock, or significant respiratory depression
- Aggressive patients (may disinhibit bite inhibition and worsen aggression)
- Tachycardia secondary to thyrotoxicosis or cardiac insufficiency
- Myocardial ischemia
- Gastrointestinal obstructive disease or paralytic ileus
- Severe ulcerative colitis
- Obstructive uropathy
- Myasthenia gravis
- Known or suspected GI infections (may prolong retention of toxins/pathogens)
Efectos adversos
- Paradoxical CNS excitement or agitation (especially in dogs)
- Variable sedation and lethargy
- Behavioral changes (irritability, aberrant demeanor in cats)
- Potential hepatotoxicity (idiosyncratic hepatic failure reported with oral diazepam in cats; unknown if chlordiazepoxide shares this risk)
- Dry mouth (xerostomia)
- Constipation or dysphagia
- Urinary retention or hesitancy
- Tachycardia (at higher doses) or initial bradycardia
Interacciones farmacológicas
- Digoxin · Pharmacologic effects of digoxin may be increased; clidinium may also increase serum levels of slow-dissolving digoxin.
- CNS Depressants (barbiturates, opiates, anesthetics) · Additive CNS depression and sedative effects.
- Probenecid · May interfere with benzodiazepine metabolism in the liver, causing increased or prolonged effects.
- Rifampin · May induce hepatic microsomal enzymes and decrease the pharmacologic effects of benzodiazepines.
- Cimetidine · May decrease the metabolism of chlordiazepoxide, leading to excessive sedation.
- Erythromycin · May decrease the metabolism of chlordiazepoxide, leading to excessive sedation.
- Fluoxetine · May decrease the metabolism of chlordiazepoxide, leading to excessive sedation.
- Isoniazid · May decrease the metabolism of chlordiazepoxide, leading to excessive sedation.
- Ketoconazole · May decrease chlordiazepoxide metabolism. Additionally, increased gastric pH from clidinium may decrease GI absorption of ketoconazole (administer clidinium 2 hours after ketoconazole).
- Metoprolol · May decrease the metabolism of chlordiazepoxide, leading to excessive sedation.
- Propranolol · May decrease the metabolism of chlordiazepoxide, leading to excessive sedation.
Monitorización
- Clinical efficacy (reduction in anxiety, resolution of GI spasms/diarrhea)
- Adverse effects (excessive sedation, paradoxical excitement, anticholinergic signs)
- Baseline and periodic liver function tests in cats (due to idiosyncratic hepatotoxicity risks associated with oral benzodiazepines)
Sobredosis
Overdoses of chlordiazepoxide alone are generally limited to significant **CNS depression** (confusion, coma, decreased reflexes). Hypotension, respiratory depression, and cardiac arrest are possible but rare. **Treatment**: * Standard protocols for acute oral toxicity (gastric decontamination, binding agents like activated charcoal). * Supportive systemic measures (fluids, cardiovascular support). * **Flumazenil** may be considered as a specific reversal agent for severe benzodiazepine-induced CNS depression. * Analeptic agents (CNS stimulants like caffeine) are 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.