온단세트론

항구토제 - 5-HT3 수용체 길항제

온단세트론은 중추 및 말초에 작용하는 매우 효과적인 **항구토제**로, 5-HT3 수용체 길항제 계열에 속합니다. 주요 임상 특징: * **난치성 구토**: 마로피탄트나 메토클로프라미드와 같은 기존 치료법이 불충분할 때 구제 또는 2차 항구토제로 자주 사용됩니다. * **화학요법 및 중증 질환**: 시스플라틴과 같은 최구토성이 높은 약물로 인한 화학요법 유발 구역 및 구토(CINV)를 예방하고 치료하는 데 있어 표준 치료제로 간주됩니다. 또한 **파르보바이러스 장염**, **췌장염**, **요독증**의 중증 사례에 널리 사용됩니다. * **종별 고려사항**: 개에서는 일반적으로 내약성이 좋습니다. 고양이에서의 사용은 역사적으로 논란이 있었으나, 현재는 난치성 구토 및 중증 췌장염에 대해 고양이 임상에서 빈번하게 사용되며 좋은 임상적 성공을 거두고 있습니다. > **임상 팁**: 온단세트론은 위장관 운동 촉진 특성이 없습니다. 위 정체나 장폐색이 있는 경우 운동성 문제를 해결하지 못하며 기저의 위 확장 증상을 은폐할 수 있습니다.

작용 기전: Ondansetron is a highly selective and competitive **5-HT3 (serotonin type 3) receptor antagonist**. * **Peripheral Action**: Cytotoxic drugs, severe inflammation (e.g., pancreatitis), or viral infections (e.g., parvovirus) cause cellular damage in the GI tract, triggering the release of serotonin from enterochromaffin cells. This serotonin binds to 5-HT3 receptors on vagal afferent nerve terminals, sending emetogenic signals to the brain. Ondansetron blocks these peripheral receptors. * **Central Action**: It also directly antagonizes 5-HT3 receptors located in the **Chemoreceptor Trigger Zone (CTZ)** within the area postrema of the brainstem, preventing central emetic signaling to the vomiting center. * **Net Effect**: Profound inhibition of the vomiting reflex without altering GI motility or causing significant sedation.

동물 종별 용량

Cats

Empiric dose · 0.5 mg/kg IV or PO twice daily. · IV/PO · q12h
Anti-emetic for intractable vomiting · 0.1-0.15 mg/kg slow IV push q6-12h as needed · IV · q6-12h · as needed
Antiemetic for adjunctive treatment of severe pancreatitis · 0.1-1 mg/kg PO or IV q12-24h · PO/IV · q12-24h
All uses (nausea and vomiting) · 0.5 mg/kg loading dose followed by 0.5 mg/kg/h infusion · IV · infusion for 6 hours · 6 hours · Used when signs are not controlled by other drugs.
All uses (nausea and vomiting) · 0.5-1 mg/kg · PO · q12-24h · As needed · Oral bioavailability is considered to be low. Subcutaneous administration is more bioavailable.

Dogs

Severe vomiting (including parvovirus or pancreatitis) · 0.1-0.3 mg/kg IV given as a slow push every 8 to 12 hours (based on patient response). · IV · q8-12h · Has produced dramatic results in controlling or decreasing frequency of vomiting.
Chemotherapy-related vomiting · 0.5-1 mg/kg PO q8-12h; 0.1-0.5 mg/kg IV over 15 minutes q8h or 30 minutes before cisplatin infusion. · PO/IV · q8-12h
Adjunctive therapy of acute diarrhea · 0.5-1 mg/kg PO twice daily. · PO · q12h · Antagonizes neuronal 5-HT3 receptors and inhibits Cl- and H2O secretion from intestinal epithelial cells.
Antiemetic · 0.1-0.2 mg/kg IV q6-12h or 0.1-1 mg/kg PO q1224h · IV/PO · q6-12h (IV) or q12-24h (PO)

투여 경로

POIVSCRectal

금기

Hypersensitivity to ondansetron or other 5-HT3 antagonists
Concurrent use with apomorphine (due to risk of severe hypotension)
Intestinal obstruction

이상반응

Constipation
Sedation
Extrapyramidal clinical signs (head shaking)
Arrhythmias
Hypotension
Headaches (reported in humans)
Alterations in liver enzymes
Hypersensitivity reactions (rare)

약물 상호작용

Apomorphine · Severe hypotension reported in humans; concurrent use is contraindicated.
Drugs affecting QTc interval (e.g., amiodarone, cisapride, halothane, isoflurane, sotalol) · Theoretically may have additive effects on QTc interval, potentially resulting in serious arrhythmias.
Tramadol · May reduce the efficacy of both drugs (human data); veterinary significance is unknown. · moderate

모니터링

Clinical efficacy (reduction or cessation of vomiting)
Hydration status and electrolyte balance (due to underlying vomiting)
Resolution of nausea and vomiting
Liver enzymes (with prolonged use)
Bowel movements (monitor for constipation)

과용량

Overdoses of up to 10X did not cause significant morbidity in human subjects. If an overdose occurs, treat supportively.

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