ヒヨスチアミン

動物種別の用量

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

• Hypersensitivity to hyoscyamine or other belladonna alkaloids
• Glaucoma (narrow or wide angle)
• Intestinal obstruction or intestinal atony
• Toxic megacolon
• Severe ulcerative colitis
• Obstructive uropathy
• Acute hemorrhage with cardiovascular instability

有害事象

• Mydriasis (pupil dilation)
• Xerostomia (dry mouth)
• Constipation
• Urinary retention
• Xerophthalmia (dry eyes)
• Tachycardia
• CNS effects (somnolence, delirium, or paradoxical excitement at higher doses)

薬物相互作用

• Antacids (magnesium, aluminum, calcium salts) · May interfere with the gastrointestinal absorption of hyoscyamine.
• Other Anticholinergics (e.g., atropine, glycopyrrolate) · Additive anticholinergic actions and increased risk of adverse effects.
• First-Generation Antihistamines (e.g., diphenhydramine) · Additive anticholinergic actions and increased risk of adverse effects.
• Prokinetic Agents (e.g., cisapride, metoclopramide) · Hyoscyamine may antagonize and counteract their gastrointestinal prokinetic effects.

モニタリング

• Clinical efficacy (resolution of GI spasms or improvement in heart rate)
• Heart rate and rhythm
• Bowel elimination (monitor for constipation/ileus)
• Urinary elimination (monitor for urinary retention)

過量投与

Significant overdosage can be life-threatening; contacting an animal poison control center is strongly advised. The LD50 in rats is 375 mg/kg. **Clinical Signs of Toxicity:** * Intensified anticholinergic effects: severe tachycardia, mydriasis, urinary retention, and absent gut sounds (ileus). * CNS signs: behavioral changes, severe depression, delirium, or seizures. **Treatment:** * **Decontamination:** Protocols to decrease oral absorption (e.g., emesis, activated charcoal) should be considered if the overdose was recent and the patient is asymptomatic. * **Antidote:** Severe anticholinergic effects can be treated with **physostigmine** or **neostigmine**, but this should *only* be done under the strict guidance of a poison control center due to the risk of cholinergic crisis. * **Supportive Care:** Delirium or excitement can be managed with small doses of short-acting barbiturates or benzodiazepines. Hyoscyamine can be removed by hemodialysis.