チレタミン / ゾラゼパム
**チレタミン/ゾラゼパム**（一般的な商品名：**Telazol®**）は、獣医療で広く使用されている注射用の麻酔・精神安定薬の配合剤です。2つの異なる薬理学的薬剤が1:1の割合で配合されています： * **チレタミン**：ケタミンと化学的に関連する解離性麻酔薬で、深い鎮痛と健忘をもたらします。 * **ゾラゼパム**：ベンゾジアゼピン系のマイナートランキライザーであり、筋弛緩、抗不安作用を提供し、解離性麻酔薬単独で通常見られる筋肉の硬直や痙攣のリスクを打ち消します。 犬および猫の保定、小手術、麻酔用としてFDAに正式に承認されていますが、馬、反芻動物、豚、鳥類、爬虫類、エキゾチック/野生動物など、非常に多くの種で適応外使用として広く用いられています。 > **臨床のポイント：** 2つの成分の作用時間は動物種によって異なります。**犬**ではチレタミンの作用がゾラゼパムより長く続くため、麻酔時間よりも鎮静時間が短くなります（覚醒が荒れる可能性があります）。**猫**ではゾラゼパムの作用がチレタミンより長く続くため、覚醒時に長時間の鎮静状態が得られます。
作用機序: The combination works synergistically through two distinct central nervous system pathways: * **Tiletamine** acts as a non-competitive **NMDA (N-methyl-D-aspartate) receptor antagonist**. By blocking the excitatory neurotransmitter glutamate at the NMDA receptor → it prevents calcium influx into neurons → inducing a state of **dissociative anesthesia** characterized by catalepsy, profound somatic analgesia, and amnesia, while maintaining cranial nerve reflexes (e.g., palpebral, laryngeal). * **Zolazepam** acts as a **GABA-A receptor agonist**. It binds to the benzodiazepine site on the GABA-A receptor complex → enhances the binding of the inhibitory neurotransmitter GABA → increases chloride ion influx → resulting in hyperpolarization of the neuron. This provides **muscle relaxation, anxiolysis, and anticonvulsant effects**, smoothing the induction and recovery phases of the dissociative anesthetic.
動物種別の用量
- Induction agent · Xylazine at 0.05-0.1 mg/kg IV, IM, then Telazol at 2-4 mg/kg IV (IM) · IV/IM · Once · Caution: xylazine can cause severe hypoxemia and pulmonary edema in sheep.
- Induction agent · Xylazine at 0.05-0.1 mg/kg IV, IM, then Telazol at 2-4 mg/kg IV (IM) · IV/IM · Once
- Procedures such as dentistry, abscess treatment, foreign body removal · 9.7-11.9 mg/kg · IM · Once · Max total dose 72 mg/kg. Use Atropine 0.04 mg/kg concurrently.
- Procedures requiring mild to moderate analgesia (lacerations, castration) · 10.6-12.5 mg/kg · IM · Once · Max total dose 72 mg/kg. Use Atropine 0.04 mg/kg concurrently.
- Ovariohysterectomy and onychectomy · 14.3-15.8 mg/kg · IM · Once · Max total dose 72 mg/kg. Use Atropine 0.04 mg/kg concurrently.
- General anesthesia/restraint · 3-10 mg/kg IM or SC or 2-5 mg/kg IV · IM/SC/IV · Once · Based upon the combination of drugs.
- Sedative/analgesic · 22 mg/kg IM combined with glycopyrrolate (0.01 mg/kg IM) · IM · Once · Rapid onset, but slow and rough recovery (3-4 hours)
- Sedative/analgesic · 22 mg/kg · IM · Once · Telazol alone
投与経路
禁忌
- Pancreatic disease
- Severe cardiac disease
- Severe pulmonary disease
- Rabbits (due to reports of renal toxicity/nephrosis)
- Large exotic cats, especially tigers (may cause seizures, permanent neurologic abnormalities, or death)
- Cesarean section (crosses placenta, causes fetal respiratory depression)
有害事象
- Respiratory depression and transient apnea
- Pain upon IM injection (especially in cats due to low pH)
- Athetoid movements (involuntary writhing/twitching)
- Tachycardia (especially in dogs)
- Emesis during emergence
- Excessive salivation and bronchial/tracheal secretions
- Vocalization and erratic/prolonged recovery
- Hypothermia
- Muscle rigidity or hypertonia
- Hypertension or hypotension
- Cyanosis, pulmonary edema, or cardiac arrest (rare/at high doses)
薬物相互作用
- Inhalational Anesthetics · Dosage may need to be reduced when used concomitantly with Telazol.
- Barbiturates · Dosage may need to be reduced when used concomitantly with Telazol.
- Chloramphenicol · In cats, anesthesia is prolonged on average by 30 minutes. No apparent effect on recovery times in dogs.
- Phenothiazines · Can cause increased respiratory and cardiac depression.
- Neuromuscular Blockers (e.g., succinylcholine) · May cause enhanced or prolonged respiratory depression (extrapolated from ketamine).
- Thyroid Hormones · May induce hypertension and tachycardia (extrapolated from ketamine).
- Azole Antifungals (ketoconazole, itraconazole) · May increase zolazepam (benzodiazepine) levels.
- Calcium Channel Blockers (diltiazem, verapamil) · May increase zolazepam levels.
- Cimetidine · May increase zolazepam levels.
- Macrolides (erythromycin, clarithromycin) · May increase zolazepam levels.
- Opiates · May increase hypnotic effects and risk of hypotension/respiratory depression.
- Phenobarbital · May decrease peak levels and AUC of zolazepam.
モニタリング
- Level of anesthesia and analgesia
- Respiratory function (rate, depth, pulse oximetry)
- Cardiovascular status (heart rate, rhythm, blood pressure)
- Body temperature (monitor for hypothermia)
- Eye moisture and corneal integrity (especially in cats)
過量投与
The manufacturer claims a 2X margin of safety in dogs and a 4.5X margin of safety in cats. * **Clinical Signs:** Excessive respiratory depression, prolonged anesthesia, potential cardiovascular collapse. * **Treatment:** In massive overdoses, mechanically assisted ventilation should be performed if necessary. Treat other clinical signs symptomatically and supportively. * **Reversal/Stimulation:** A preliminary study in dogs suggests that **doxapram** at 5.5 mg/kg will enhance respirations and arousal after Telazol administration. > **Note:** High doses of tiletamine have caused acute tubular necrosis in New Zealand white rabbits.
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