苯乙哌啶與阿托品
**苯乙哌啶 (Diphenoxylate)** 是一種合成的苯基哌啶衍生物鴉片類促效劑，結構上與配西汀 (meperidine) 相似。在獸醫學中主要用作**止瀉藥**和**鎮咳藥**（抑制咳嗽），最常用於犬隻。 主要藥理特徵包括： * **調節腸道蠕動**：減緩胃腸道排空時間，促進水分吸收，從而減少腹瀉。 * **防濫用機制**：商業製劑中含有亞治療劑量的**硫酸阿托品 (atropine sulfate)**。在正常劑量下，阿托品不會產生臨床作用；但若過量服用，會產生令人不適的抗膽鹼副作用（如口乾、心跳過速），藉此防止藥物濫用。 * **管制藥物**：由於其鴉片類特性，被歸類為**第五級管制藥品**。 > **臨床要點**：由於可能引起矛盾的興奮行為，本藥在貓的使用極具爭議。對於體重低於 10 公斤的犬隻，強烈建議使用液體製劑，以便精確調整劑量，避免因高濃度錠劑導致意外過量。
作用機制: Diphenoxylate exerts its effects primarily through interaction with opioid receptors in the gastrointestinal tract and central nervous system: * **GI Motility**: Binds to **μ-opioid receptors** in the enteric nervous system (myenteric plexus) → decreases the release of acetylcholine and prostaglandins → inhibits excessive GI propulsion and increases segmental (non-propulsive) contractions → **prolongs intestinal transit time**. * **Secretion Reduction**: Decreases intestinal secretion induced by cholera toxin, prostaglandin E2, and non-cAMP/cGMP mediated diarrheas. Enhances mucosal fluid and electrolyte absorption. * **Antitussive Effect**: Acts directly on the **medullary cough center** in the brain → depresses the cough reflex. * **Atropine Component**: Acts as a competitive antagonist at **muscarinic acetylcholine receptors**, though its dose in this combination is too low to exert significant systemic anticholinergic effects unless overdosed.
各物種劑量
- As an antidiarrheal · 0.08-0.1 mg/kg PO q12h · PO · q12h · Use in cats is controversial.
- As an antidiarrheal · 0.1-0.2 mg/kg PO q12h · PO · q12h
- As an antidiarrheal · 0.05 mg/kg PO three times a day · PO · TID · Maximum 5 days · Probably should not be given longer than 5 days and are potentially contraindicated when diarrhea is suspected to be caused by enteric infections
- As an antidiarrheal · 0.05-0.2 mg/kg PO q8-12h · PO · q8-12h
- As an antidiarrheal · 0.05-0.1 mg/kg PO three to four times a day. · PO · TID to QID
- As an antitussive · Approximately 0.25 mg/kg PO q8-12h · PO · q8-12h
- As an antitussive · 0.2-0.5 mg/kg PO q12h · PO · q12h · Until clinical signs subside · May be used for extended periods. Constipation is an occasional problem, but stool softeners can alleviate.
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- Known hypersensitivity to narcotic analgesics
- Patients receiving monoamine oxidase inhibitors (MAOIs)
- Diarrhea caused by toxic ingestion (until the toxin is eliminated from the GI tract)
- Intestinal obstruction
- Bacterial-induced acute diarrhea (may enhance bacterial proliferation)
不良反應
- Constipation
- Bloat
- Sedation
- Paralytic ileus (potential)
- Toxic megacolon (potential)
- Pancreatitis (potential)
- CNS depression or excitation
- Excitatory behavior (especially in cats)
藥物相互作用
- CNS Depressant Drugs (anesthetics, antihistamines, phenothiazines, barbiturates, tranquilizers, alcohol) · May cause increased CNS or respiratory depression when used concurrently.
- Monoamine Oxidase Inhibitors (MAOIs) (e.g., amitraz, selegiline) · Contraindicated. Do not use opiate antidiarrheals for at least 14 days after receiving MAOIs due to risk of severe adverse reactions.
監測
- Clinical efficacy (resolution of diarrhea or cough)
- Fluid and electrolyte status (especially in severe diarrhea)
- CNS effects (sedation or excitation), particularly if using high dosages
- Bowel movements (monitor for constipation)
- Plasma amylase and lipase (may be artificially increased for up to 24 hours post-administration)
過量
Acute overdosage can result in severe **CNS, cardiovascular, gastrointestinal, or respiratory toxicity**. * **Delayed Absorption**: Because opiates significantly reduce GI motility, absorption of the drug from the GI tract may be delayed and prolonged, meaning toxicity can worsen over time. * **Opiate Toxicity**: Signs include profound sedation, respiratory depression, and pinpoint pupils. **Naloxone** may be necessary to reverse the opiate effects. * **Atropine Toxicity**: Massive overdoses may induce atropine toxicity (dry mouth, tachycardia, hyperthermia, dilated pupils, agitation).
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。