Chemistry - Tiletamine is an injectable anesthetic agent chemically related to ketamine. Zolazepam is a diazepinone minor tranquilizer. The pH of the injectable product after reconstitution is 2.2 - 2.8.

Storage/Stability/Compatibility - After reconstitution, solutions may be stored for 4 days at room temperature and 14 days if refrigerated. Do not use solutions that contain a precipitate or are discolored.

Pharmacology - In cats, tiletamine decreases cardiac rate and blood pressure after IM injections. Its effect on respiratory activity is controversial, and until these effects have been clarified respiratory function should be closely monitored. The pharmacology of this drug combination is similar to that of ketamine and diazepam. For more information refer to the monographs for those agents.

Uses/Indications - TelazolŽ is indicated for restraint or anesthesia combined with muscle relaxation in cats, and for restraint and minor procedures of short duration (~30 minutes) which require mild to moderate analgesia in dogs. Although not officially approved, it has been used also in horses and many exotic and wild species.

Pharmacokinetics - Little pharmacokinetic information is available for these agents. The onset of action may be variable and be very rapid; animals should be observed carefully after injection.

In cats, the onset of action is reported to be within 1-7 minutes after IM injection. Duration of anesthesia is dependent on dosage, but is usually about 0.33-1 hour at peak effect. This is reported to be approximately 3 times the duration of ketamine anesthesia. The duration of effect of the zolazepam component is longer than that of the tiletamine, so there is a greater degree of tranquilization than anesthesia during the recovery period. The recovery times vary in length from approximately 1-5.5 hours.

In dogs, the onset of action following IM injection averages 7.5 minutes. The mean duration of surgical anesthesia is about 27 minutes, with recovery times averaging approximately 4 hours. The duration of the tiletamine effect is longer than that of zolazepam, so there is a shorter duration of tranquilization than there is anesthesia. Less than 4% of the drugs are reported to be excreted unchanged in the urine in the dog.

Contraindications/Precautions - TelazolŽ is contraindicated in animals with pancreatic disease, severe cardiac or pulmonary disease. Animals with renal disease may have prolonged durations of anesthetic action or recovery times.

TelazolŽ crosses the placenta and may cause respiratory depression in newborns; the manufacturer lists its use in cesarian section as being contraindicated. The teratogenic potential of the drug is unknown, and it is not recommended to be used during any stage of pregnancy.

Because TelazolŽ may cause hypothermia, susceptible animals (small body surface area, low ambient temperatures) should be monitored carefully and supplemental heat applied if needed. Like ketamine, TelazolŽ does not abolish pinnal, palpebral, pedal, laryngeal, and pharyngeal reflexes and its use (alone) may not be adequate if surgery is to be performed on these areas.

This drug has been reported to be contraindicated in rabbits.

Cat's eyes remain open after receiving TelazolŽ , and they should be protected from injury and an ophthalmic lubricant (e.g., LacrilubeŽ) should be applied to prevent excessive drying of the cornea. Cats reportedly do not tolerate endotracheal tubes well with this agent.

Dosages may need to be reduced in geriatric, debilitated, or animals with renal dysfunction.

Adverse Effects/Warnings - Respiratory depression is a definite possibility, especially with higher dosages of this product. Apnea may occur; observe animal carefully. Pain after IM injection (especially in cats) has been noted which may be a result of the low pH of the solution. Athetoid movements (constant succession of slow, writhing, involuntary movements of flexion, extension, pronation, etc) may occur; do not give additional TelazolŽ in the attempt to diminish these actions.

In dogs, tachycardia may be a common effect and may last for 30 minutes. Insufficient anesthesia after recommended doses has been reported in dogs.

Other adverse effects listed by the manufacturer include: emesis during emergence, excessive salivation and bronchial/tracheal secretions (if atropine not administered beforehand), transient apnea, vocalization, erratic and/or prolonged recovery, involuntary muscular twitching, hypertonia, cyanosis, cardiac arrest, pulmonary edema, muscle rigidity, and either hypertension or hypotension.

Overdosage - The manufacturer claims a 2X margin of safety in dogs, and a 4.5 times margin of safety in cats. A preliminary study in dogs (Hatch et al. 1988) suggests that doxapram at 5.5 mg/kg will enhance respirations and arousal after TelazolŽ. In massive overdoses, it is suggested that mechanically assisted ventilation be performed if necessary and other symptoms be treated symptomatically and supportively.

Drug Interactions - Little specific information is available presently on drug interactions with this product. In dogs, chloramphenicol apparently has no effect on recovery times with TelazolŽ, but in cats, anesthesia is prolonged on average of 30 minutes by chloramphenicol. Cats wearing flea collars have not been demonstrated to have prolonged anesthesia times.

Phenothiazines can cause increased respiratory and cardiac depression when used with this product.

The dosage of barbiturate or volatile anesthetics may need to be reduced when used concomitantly with TelazolŽ. For general guidelines with regard to drug interactions with this product, please refer to the ketamine and diazepam monographs.

Doses -

Dogs:

a) For diagnostic purposes: 6.6 - 9.9 mg/kg IM

For minor procedures of short duration: 9.9 - 13.2 mg/kg IM

If supplemental doses are necessary, give doses less than the initial dose and total dosage should not exceed 26.4 mg/kg. Atropine 0.04 mg/kg should be used concurrently to control hypersalivation. (Package Insert; TelazolŽ - Robins)

b) For surgical interventions of 30-60 minutes: 6 - 13 mg/kg IM (Booth 1988a)

Cats:

a) 9.7 - 11.9 mg/kg IM for procedures such as dentistry, abscess treatment, foreign body removal, etc. For procedures that require mild to moderate levels of analgesia (lacerations, castration, etc.) use 10.6 - 12.5 mg/kg IM.

For ovariohysterectomy and onychectomy use 14.3 - 15.8 mg/kg IM.

If supplemental doses are necessary, give doses less than the initial dose and the total dosage should not exceed 72 mg/kg. Atropine 0.04 mg/kg should be used concurrently to control hypersalivation. (Package Insert; TelazolŽ - Robins)

b) For surgical interventions of 30-60 minutes: 6 - 13 mg/kg IM (Booth 1988a)

Pocket Pets:

Gerbils: 20 mg/kg IP (in combination with xylazine 10 mg/kg) (Huerkamp 1995)

Horses:

a) Xylazine 1.1 mg/kg IV, 5 minutes prior to TelazolŽ at 1.65 - 2.2 mg/kg IV (Hubbell, Bednarski, and Muir 1989)

Exotic Species:

a) An extensive list of suggested TelazolŽ dosages may be found in the article by E. Schobert entitled, "TelazolŽ Use in Wild and Exotic Animals" in the October 1987 issue of Veterinary Medicine.

Monitoring Parameters -

1) Level of anesthesia/analgesia

2) Respiratory function; cardiovascular status (rate, rhythm, BP if possible)

3) Monitor eyes to prevent drying or injury

4) Body temperature

Client Information - Should only be administered by individuals familiar with its use.

Dosage Forms/Preparations/FDA Approval Status/Withholding Times -

Veterinary-Approved Products:
Tiletamine HCl (equivalent to 250 mg free base) & Zolazepam HCl (equivalent to 250 mg free base) as lyophilized powder/vial in 5 ml vials. When 5 ml of sterile diluent (sterile water) is added a concentration of 50 mg/ml of each drug (100 mg/ml combined) is produced.; TelazolŽ (Fort Dodge); (Rx) Approved for use in cats and dogs. TelazolŽ is a Class III controlled substance.

Human-Approved Products: None


--------------------------------------------------------------------------------

COPYRIGHT Š 1999 by Donald C. Plumb, Pharm.D Hospital Director, Veterinary Teaching Hospitals, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota