米索前列醇
米索前列醇（Misoprostol）是一種合成的**前列腺素E1（PGE1）類似物**，在獸醫學中主要用於預防和治療因使用非類固醇抗發炎藥（NSAIDs）引起的胃潰瘍。 NSAIDs會抑制環氧化酶（COX），導致胃黏膜中具保護作用的前列腺素減少；米索前列醇能有效補充這些流失的前列腺素，從而恢復黏膜防禦機制。 除了胃腸道的應用外，米索前列醇還具有強烈的子宮收縮特性。它能增加子宮收縮力並促進子宮頸鬆弛，使其成為生殖系統適應症（如**終止妊娠**、**治療子宮蓄膿/子宮炎**以及交配後處置）的重要輔助療法。 *臨床要點：* 雖然它曾被研究用於異位性皮膚炎和環孢素引起的腎毒性，但由於療效有限且胃腸道副作用普遍，通常不作為這些疾病的首選藥物。
作用機制: Misoprostol exerts its effects through multiple prostaglandin (EP) receptors across different organ systems: * **Gastric Acid Suppression:** Binds directly to **EP3 receptors** on gastric parietal cells → inhibits adenylate cyclase → decreases intracellular cAMP → reduces the activity of the apical H+/K+ ATPase proton pump → **decreased basal and stimulated gastric acid secretion**. * **Gastric Cytoprotection:** Binds to **EP receptors** on superficial foveolar epithelial cells → stimulates the secretion of protective **mucin and bicarbonate**. It also increases mucosal blood flow and accelerates epithelial cell turnover, enhancing the overall mucosal barrier and healing capacity. * **Reproductive Tract:** Binds to **EP receptors** in the myometrium → increases intracellular calcium concentrations → increases the amplitude and frequency of **uterine contractions**. It also induces collagen breakdown in the cervix, leading to **cervical softening and dilation**.
各物種劑量
- Induction of abortion · Dose not specified in text · PO · Not specified · Not specified · Used in combination with aglepristone
- Adjunctive treatment of acute colitis · 5 micrograms/kg · PO · q8h · Route not listed in original source; assumed PO by Plumb.
- Equine gastric ulcer syndrome · 5 micrograms/kg · PO · q8h
- Induce cervical relaxation (post-breeding endometritis) · 1000 micrograms (total dose) · topical · once · Applied as a compounded cream to the caudal os and lumen of the cervix after lavage. Oxytocin (20 Units IM) administered immediately following lavage and again every 6 hours until the following morning.
- Prevention of aspirin-induced gastric injury · 3 micrograms/kg · PO · q12h or q8h · Study suggests q12h is as effective as q8h.
- Prevention or treatment of gastric ulceration from NSAIDs · 2-5 micrograms/kg · PO · four times daily · Uncertain if it improves healing of established ulcers; no distinct advantage over other antacids for non-NSAID ulcers.
- Prevention or treatment of gastric ulceration from NSAIDs · 2-5 micrograms/kg · PO · q8-12h
- Preventing GI mucosal injury in dogs with arthritis requiring long-term NSAID therapy; treating gastro-duodenal ulcer disease caused by NSAIDS · 3 micrograms/kg · PO · three times a day
給藥途徑
禁忌症
- Pregnancy (unless being used specifically as an abortifacient)
- Nursing mothers (can cause severe diarrhea in nursing offspring)
- Known sensitivity to prostaglandins or prostaglandin analogs
- Pregnant animals (unless being used specifically to induce abortion)
不良反應
- Diarrhea
- Abdominal pain
- Vomiting
- Flatulence
- Uterine contractions (in females)
- Vaginal bleeding (in females)
- Diarrhoea
- Nausea
- Abortion
藥物相互作用
- Magnesium-containing antacids · May aggravate misoprostol-induced diarrhea. If an antacid is required, an aluminum-only antacid is preferred.
- Gentamicin · May exacerbate renal dysfunction · moderate
- Diclofenac · Human combination products (misoprostol + diclofenac) are highly toxic to small animals due to different NSAID pharmacokinetics · major
監測
- Clinical efficacy (resolution of ulcer signs, successful pregnancy termination, etc.)
- Adverse effects (GI distress, diarrhea, vomiting)
- Vaginal bleeding or discharge (if used in females)
- Resolution of clinical signs of gastric ulceration (e.g., vomiting, melena, anorexia)
- Monitoring for adverse GI effects (diarrhoea, abdominal pain)
過量
Information on acute toxicity is limited. Overdoses in laboratory animals have produced: * Diarrhea and emesis * GI lesions * Tremors and seizures * Focal cardiac, hepatic, or renal tubular necrosis * Hypotension **Treatment:** Overdoses should be treated seriously. Employ standard gut-emptying techniques (e.g., emesis induction, activated charcoal) when applicable and safe. Treat resultant toxicity symptomatically with supportive care (e.g., IV fluids for hypotension and GI fluid loss).
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。