トリメプラジン・プレドニゾロン配合剤
**トリメプラジンとプレドニゾロンの配合剤**（一般的な商品名：Temaril-P®）は、主に犬の掻痒（かゆみ）や咳を管理するために獣医療で広く使用される配合薬です。 * **トリメプラジン**（別名：アリメマジン）はフェノチアジン誘導体であり、強力な抗ヒスタミン作用、軽度の鎮静作用、および鎮咳作用を示します。 * **プレドニゾロン**は中時間作用型のグルココルチコイドであり、強力な抗炎症作用および免疫抑制作用を提供します。 > **臨床のポイント：** 抗ヒスタミン薬とコルチコステロイドを組み合わせる相乗効果により、より低用量のプレドニゾロンで同等の止痒効果を得ることができます。この「ステロイド節減」アプローチにより、臨床症状を効果的にコントロールしつつ、長期的なグルココルチコイド誘発性の副作用リスクを最小限に抑えることができます。
作用機序: The drug exerts its effects through two distinct mechanisms: * **Trimeprazine**: Acts primarily as a competitive antagonist at **H1-histamine receptors**, preventing histamine-induced capillary permeability, vasodilation, and pruritus. It also exhibits central antitussive and sedative properties by antagonizing central **dopamine (D2)** and **muscarinic (M1)** receptors in the brainstem and reticular activating system. * **Prednisolone**: Diffuses across cell membranes and binds to **cytosolic glucocorticoid receptors**. The receptor-ligand complex translocates to the nucleus → alters gene transcription → induces production of lipocortin-1 (annexin-1) → inhibits **phospholipase A2**. This blocks the release of arachidonic acid, thereby suppressing the synthesis of key inflammatory mediators, including **prostaglandins** and **leukotrienes**.
動物種別の用量
- Antipruritic and antitussive therapy · Weight up to 10 lb = 1/2 tab PO twice daily; 11-20 lb = 1 tablet twice daily; 21-40 lb = 2 tablets twice daily; over 40 lb = 3 tablets twice daily. After 4 days reduce dose to 1/2 of initial dose or to an amount just sufficient to maintain remission of symptoms; adjust as necessary. · PO · twice daily · After 4 days reduce dose
- Treatment of pruritus · 1 tablet per 10 kg of body weight once daily for 3-5 days, then every other day. · PO · once daily then every other day · 3-5 days then every other day · Giving with an EFA (essential fatty acid) may reduce the dose and frequency, if not the need for, glucocorticoids.
- Atopic dermatitis · 1 tablet of Temaril-P per 5 kg body weight q12h for one week, then once daily for one week, then q48h (every other day). · PO · q12h then once daily then q48h · 1 week q12h, 1 week once daily, then q48h
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
- Systemic fungal infections
- Hypovolemia or shock
- Tetanus or strychnine intoxication
- Late pregnancy (last trimester) due to risk of inducing parturition
有害事象
- Sedation
- Depression
- Hypotension
- Extrapyramidal reactions (rigidity, tremors, weakness, restlessness)
- Polyuria (increased urination)
- Polydipsia (increased thirst)
- Polyphagia (increased appetite)
- Elevated liver enzymes
- Weight loss or weight gain
- Vomiting
- Diarrhea
- Iatrogenic hyperadrenocorticism (Cushing's syndrome) with chronic use
- Delayed wound healing
- Osteoporosis
- Increased susceptibility to infections
薬物相互作用
- ACE Inhibitors · Phenothiazines may increase hypotensive effects
- Amphotericin B · Concomitant use with glucocorticoids may cause severe hypokalemia
- Antacids · May cause reduced GI absorption of oral phenothiazines
- Antidiarrheal mixtures (Kaolin/pectin, bismuth) · May cause reduced GI absorption of oral phenothiazines
- Anticholinesterase agents (pyridostigmine, neostigmine) · In myasthenia gravis patients, concomitant use may lead to profound muscle weakness
- Aspirin (salicylates) · Glucocorticoids may reduce salicylate blood levels
- Cisapride · Increased risk for cardiac arrhythmias when used with phenothiazines
- CNS Depressants (barbiturates, narcotics, anesthetics) · May cause additive CNS depression
- Cyclophosphamide · Glucocorticoids may inhibit hepatic metabolism of cyclophosphamide
- Cyclosporine · May mutually inhibit hepatic metabolism, increasing blood levels of both drugs
- Digoxin · Increased risk for arrhythmias secondary to glucocorticoid-induced hypokalemia
- Diuretics, potassium-depleting (furosemide, thiazides) · Concomitant use with glucocorticoids may cause hypokalemia
モニタリング
- Efficacy (reduction in pruritus or coughing)
- Degree of sedation
- Anticholinergic effects
- Adverse effects associated with corticosteroids (e.g., PU/PD, weight changes, liver enzyme elevations)
過量投与
Acute overdosage should be handled similarly to phenothiazine (e.g., acepromazine) toxicity. Overdose may cause profound sedation, depression, hypotension, and extrapyramidal signs (tremors, rigidity). Treatment is largely supportive and symptomatic. Do not use epinephrine for hypotension as it may cause further vasodilation (epinephrine reversal); use norepinephrine or phenylephrine if pressors are required.
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。