Telazol: Product Information (Page 3 of 4)

EFFECTIVENESS

Dogs
Preanesthesia
In a field study conducted at 6 veterinary hospitals,
144 dogs of various breeds, ranging in age from
4 months to 14 years (mean age 5 years) and
body weights from 1.2- 85.5 kg, were enrolled for
completion of a veterinary procedure requiring
anesthesia. Dogs were preanesthetized with a
phenothiazine + opioid, an opioid alone, or an
alpha2-agonist + opioid at the study Investigator’s
discretion based on individual patient needs.
Approximately 20 minutes later, dogs were
intravenously administered TELAZOL at 1-2 mg/lb
(2.2-4.4 mg/kg) ‘to effect’ of anesthesia and
were intubated. After induction, dogs received
either isoflurane or sevoflurane for anesthetic
maintenance for at least 30 minutes. Procedures
conducted included dental prophylaxis with or
without extractions (64), ovariohysterectomy
(31), castration (18), and mass removal (14).
Upon completion of the procedure, dogs were
monitored in recovery for 4 hours, then followed at
home for 2-4 days, monitoring for the presence of
abnormal clinical signs.
Of 144 dogs enrolled in the study, 142 (98.6%)
were successfully intubated after intravenous
administration of TELAZOL at a mean dosage of
1.2 mg/lb (2.7 mg/kg). The mean dosage range was
lowest in the alpha2-agonist + opioid preanesthetic
treatment group (0.9 mg/lb; 2 mg/kg) and highest
in the opioid alone preanesthetic group (1.8 mg/lb;
3.9 mg/kg).
Overall induction quality evaluated on a scale
of acceptable, intermediate, or unacceptable
was acceptable in 131/142 (91.6%) dogs and
intermediate in 12/143(8.4%) dogs. On a scale of
good, fair, or poor, study participants rated the
quality of recovery from anesthesia as good in
75% of dogs (118/144) and fair in 18.1% (26/144).
In an overall assessment of anesthesia, considering
induction, maintenance, and recovery, was scored
as excellent or good in 128/144 (88.9%) of dogs.
Three dogs (2.1%) were rated with an overall
assessment of anesthesia as poor, and for these
dogs, recovery was also rated poor. Physiologic
measurements of heart rate, respiratory rate,
body temperature, oxygen saturation, and blood
pressure during anesthetic induction, maintenance,
and recovery showed that the administration of
TELAZOL did not severely impact these variables.
A variety of concomitant treatments were used
during the study including intravenous fluid
solutions, non-steroidal anti-inflammatory
medications, antimicrobials, and antiparasitics that
were consistent with routine canine practice.

ANIMAL SAFETY

TELAZOL has a wider margin of safety in cats
than in dogs. Dogs have survived repeated
IM dosage regimens of 13.6 mg/lb (30 mg/kg)
(maximum safe dose) for eight successive days.
This is approximately two times the maximum
recommended therapeutic dose. Cats have
survived IM dosage regimens of up to 32.7 mg/
lb (72 mg/kg) (maximum safe dose) on alternate
days for seven episodes. This is 4.6 times the
maximum recommended therapeutic dose for
cats. However, these reports should not obviate
prudent anesthetic practices. Some degree of
tolerance has been reported. This tolerance
appears to be species-variable.

Cats

In cats, the duration of effect of zolazepam exceeds
that of tiletamine so that as the animal recovers
there is a greater degree of tranquilization than
anesthetization. There is a slight lowering of blood
pressure during the first hour after injection.
Heart rate and electrocardiogram readings are
unaffected by TELAZOL (tiletamine and zolazepam
for injection). Arterial pO2 levels are decreased
three minutes after injection but usually return to
normal within 15 to 35 minutes.

Dogs
In dogs, the duration of effect of tiletamine
exceeds that of zolazepam so there is a lesser
degree of tranquilization than anesthetization in
this species. The total effect of TELAZOL in dogs is
of shorter duration than in cats.
Following administration of TELAZOL in dogs, a
marked, persistent tachycardia occurs within two
minutes following either 4.5 or 9 mg/lb (10 or
20 mg/kg) TELAZOL intramuscularly. Stroke volume
decreases proportionately to the increased rate
at the 4.5 mg/lb (10 mg/kg) dose, with little
change in net cardiac output. There is an initial
increase in systolic blood pressure, with a slight
drop in pressure within five minutes. The systolic
blood pressure remains at this decreased level
throughout the duration of the anesthetic effect.
Diastolic pressure increases throughout this same
period. Following a 9 mg/lb (20 mg/kg) dose
of TELAZOL in dogs, the relationship between
stroke volume and heart rate is disproportionate,
with a resultant substantial decrease in cardiac
output. Contractility and mean blood pressure are
decreased, indicating direct myocardial depression.
Ventricular function is adequate. During surgical
manipulations, tachycardia and hypertension may
be observed, and may be brought on by sympathetic
reaction to painful stimuli. Epinephrine is markedly
less arrhythmogenic in animals under TELAZOL
anesthesia than in those under halothane anesthesia.
During TELAZOL anesthesia, the assurance of
a patent airway is greatly enhanced by virtue
of maintaining pharyngeal-laryngeal reflexes.
During the first 15 minutes after intramuscular
administration of 9 mg/lb (20 mg/kg) of TELAZOL,
the respiratory rate is doubled while the tidal
volume is decreased to less than one-half of control
values. Arterial pO2 levels also decrease. This may
be evidenced by hypoxemia and cyanosis. The
pulmonary function usually returns to normal within
35 minutes after the administration of TELAZOL.

Preanesthetic Compatibility Study in Dogs
Six healthy Beagle dogs (3 males and 3 females),
at least 8 months of age, ranging in body
weight between 5.6 and 9.4 kg, were fitted
with a telemetry device that captured systemic
arterial blood pressures, electrocardiogram, and
body temperature. Each dog received a total of
6 treatments with at least a 7-day washout between
periods. During each period, dogs received
1 of the following 6 preanesthetics prior to the
TELAZOL administration: placebo (0.9% saline),
acepromazine low dose (0.1 mg/kg body weight
[BW]), acepromazine high dose (1.1 mg/kg BW),
dexmedetomidine low dose (125 mcg/m2 body
surface area [BSA]), dexmedetomidine high dose
(375 mcg/m2 BSA), or butorphanol (0.4 mg/kg BW).
Blood samples were collected at intubation, end
of isoflurane administration, and after anesthesia
when the dogs were able to walk. Plasma
concentrations of tiletamine and zolazepam were
measured using a validated method. Preanesthetic
treatment with high dose acepromazine and both
high and low doses of dexmedetomidine resulted
in substantial increases in plasma concentrations
of tiletamine and zolazepam at intubation. The
increase in the tiletamine plasma concentrations
was approximately 2X higher for the high dose of
acepromazine and 2.7 to 4.5X higher for the low
and high doses of dexmedetomidine, respectively,
compared to saline. The increase in zolazepam
plasma concentrations was 1.5X higher for the
high dose acepromazine, and 1.8 to 2.8X higher
for the low and high doses of dexmedetomidine,
respectively, compared to saline.
No information on the dose-sparing of TELAZOL
was obtained during the study because the dogs
were given the full initial half-dose (2.2 mg/kg) and
not actually administered TELAZOL ‘to effect’. The
average total dose of test article administered to
the dogs was 2.6 mg/kg for the saline group and
2.2 mg/kg for the other treatment groups. One
dog (saline group) required more than the initial
2.2 mg/kg bolus to achieve intubation at the first
attempt.
Without preanesthesia (saline group), dogs
retained a strong cough reflex, chewing motions,
tachycardia and increased muscle tone during
intubation. With preanesthesia, half of the dogs
in the high dose dexmedetomidine group had
no laryngeal reflex response to intubation and
all experienced post-intubation apnea. The postintubation
apnea suggests that the 2.2 mg/kg dose
of TELAZOL was higher than necessary in some
groups.
All dogs in all treatment groups achieved successful
anesthetic plane following TELAZOL administration
and were intubated and induced to isoflurane
anesthesia uneventfully. The quality of intubation,
and occurrence and severity of adverse reactions
(e.g., apnea and bradypnea) following TELAZOL
administration and intubation revealed differences
among preanesthetic treatment groups. The
cardiovascular and respiratory changes observed
were typical of each preanesthetic medication used
in combination with TELAZOL. Acepromazine and
isoflurane administration decreased arterial blood
pressure. Dexmedetomidine decreased heart rate.
Intubation transiently increased heart rate and/or
blood pressure (sympathetic stimulations). Mild to
severe respiratory depression was observed after
TELAZOL administration and each preanesthetic
agent. Adverse reactions were manageable with
appropriate care.