Tiletamine / Zolazepam
**Tiletamine/Zolazepam** (commonly known by the trade name **Telazol®**) is a widely used injectable anesthetic and tranquilizer combination in veterinary medicine. It is formulated as a 1:1 ratio of two distinct pharmacological agents: * **Tiletamine**: A dissociative anesthetic chemically related to ketamine, providing profound analgesia and amnesia. * **Zolazepam**: A benzodiazepine minor tranquilizer (diazepinone) that provides muscle relaxation, anxiolysis, and counteracts the muscle rigidity and seizure potential typically associated with dissociative anesthetics. While officially FDA-approved for use in dogs and cats for restraint, minor procedures, and anesthesia, it is extensively used off-label across a vast array of species, including horses, ruminants, swine, birds, reptiles, and exotic/wildlife species. > **Clinical Pearl:** The duration of effect of the two components varies by species. In **dogs**, tiletamine outlasts zolazepam, leading to a shorter duration of tranquilization than anesthesia (potentially rougher recoveries). In **cats**, zolazepam outlasts tiletamine, resulting in a longer period of tranquilization during recovery.
Mecanismo: 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.
Dosificación por especie
- 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
Vías de administración
Contraindicaciones
- 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)
Efectos adversos
- 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)
Interacciones farmacológicas
- 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.
Monitorización
- 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)
Sobredosis
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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