クロルジアゼポキシドおよびクリジニウム
クロルジアゼポキシドは、主に抗不安作用および軽度の鎮静作用を目的として使用される長時間作用型の**ベンゾジアゼピン系薬**です。クリジニウム臭化物は、胃腸の運動や痙攣を抑える合成第四級アンモニウム**抗ムスカリン（抗コリン）**薬です。 獣医療では、これらの薬剤は単独または組み合わせて使用されることがあります： * **クロルジアゼポキシド単独**：犬の音響恐怖症や、猫の猫同士の攻撃行動、尿スプレーなどの行動障害の補助療法として使用されます。 * **クロルジアゼポキシド + クリジニウム (Librax®)**：この配合剤は、犬の**過敏性腸症候群 (IBS)** などのストレス誘発性胃腸疾患の治療に独自の位置を占めています。中枢性の不安要素（クロルジアゼポキシドによる）と末梢性の胃腸痙攣（クリジニウムによる）の両方に対処します。 > **臨床のポイント**：クリジニウムは第四級アミンであるため、血液脳関門を容易に通過せず、アトロピンでよく見られる中枢性の抗コリン性副作用を回避できます。
作用機序: 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.
動物種別の用量
- 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.
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- 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)
有害事象
- 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
薬物相互作用
- 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.
モニタリング
- 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)
過量投与
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.
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。