Sedation of Phobic
Dental Patients
With an Emphasis on the Use of Oral Triazolam
Part Three
by
Fred Quarnstrom,
D.D.S. F.A.G.D., F.A.S.D.A., F.I.C.D.
Diplomate, American Dental Society of Anesthesiology
Triazolam: a clinical
study in a general dental office
First Published:
December 1996
Introduction
Over a two year period I have used triazolam
about 150 times. Forty (40) times were for a double blind study of first time
users. This study is yet to be analyzed. One hundred and five (105) uses are reported
here. Initially, the patients were monitored by recording blood pressure and pulse.
Later, pulse oximetry was added and finally an end tidal carbon dioxide monitor.
The first time a patient used the drug we attempted to measure their amnesia.
Initially, I feel many of the patients were undersedated. However, we had little
guidance as to what dosage to use. Over time, I found sublingual administration
could be used at the 30 minute mark where inadequate sedation was inevitable.
I now have a dose-weight relationship that I am comfortable with and which rarely
fails.
Methods
The patient population included 105
patients of a private dental practice. The mean age was 25.1 years (SD 18.9 years),
with a range of 1.5 to 63 years. Average weight was 125.6 pounds (SD 83.7 pounds)
with a range of 23 to 286 pounds. All patients were ASA 1 or 2 with no history
of recent illness.
All adult patients were dental phobics
who requested IV sedation or general anesthesia for their procedures. The children
had previous attempts at treatment with conventional methods, including nitrous
oxide, which were unsuccessful.
At a pre-appointment interview medical
history was reviewed to determine that there are no contraindications to Triazolam.
The procedures, possible risks, benefits and options were discussed with the
patient or, in the case of children, with their parents. Our office protocol
was explained, including the need for an adult to take the patient home, and
the restrictions of their activities on the day of the appointment. It was stressed
that we were not attempting to have the patient asleep, although they might
experience amnesia for some or all of the appointment.
Patients assessed and recorded their
apprehension on an analogue scale graded from 0 to 6. Numbers referred to the
following states: 0 calm, relaxed; 1 a little nervous; 2 tense, upset; 3 afraid;
4 very afraid; 5 panicked; 6 terrified. Apprehension was reevaluated at 30 minutes
and 60 minutes (the start of the procedure) and at the conclusion of the procedure.
Twenty-six (26) patients were shown
5 different symbols, one at a time, for 30 seconds. These symbols were shown
at the start, at 30 minutes, at 60 minutes, half- way through the procedure,
and at its completion. They received a sealed envelope with directions to open
it the following day and circle the symbols they remembered from a sheet showing
16 symbols. They also were asked to record a narrative of their memory of the
procedure.
Cardiovascular and respiratory parameters
measured and recorded included blood pressure (systolic and diastolic), heart
rate, percentage hemoglobin-oxygen saturation and end tidal carbon dioxide levels.
With uncooperative children, only heart rate and oxygen saturation could be
measured. Cardiovascular parameters were recorded every 15 minutes until the
procedure was started. During the procedure, oxygen saturation and ETCO2
were continuously monitored by a Matrix 3700 pulse oximeter and a Matrix ETCO2
monitor.
After recording initial data, oral
Triazolam was dispensed. Many authors have reported on the appropriate dosage
for sleep enhancement. Suggested dosages range from 0.125 mg. to 0.5 mg. Initially,
doses in this study were limited to 0.125 mg. and 0.25 mg. After several cases
of inadequate sedation, I decided to administer one-half the initial dose after
30 minutes if there was no evidence of sedation. Supplemental dosages were necessary
for 16 patients. The mean dosage was 0.0042 mg per pound (SD 0.0022 mg per pound)
with a range of 0.00083 to 0.108 mg per pound.
At the close of the appointment
the operator assessed relaxation on an analogue scale graded from 0 to 6. Numbers
referred to the following: 0 asleep (to relaxed), 1 very relaxed, 2 easy to
work with - slight relaxation, 3 normal patient, 4 slight apprehension (crying
in the case of children), 5 difficult to work on and 6 uncontrollable.
Results
Patient's apprehension report
Self-reported apprehension levels fell
from an initial mean of 3.14 - SD 1.75 (afraid) to 1.97 - SD 1.49 (tense) at 30
minutes and to 1.41 SD 1.45 during the procedure and - 0.85 SD 1.28 (a little
nervous) during and after the procedure. The largest drop in apprehension occurred
in the first 30 minutes; the second largest drop in the second 30 minutes.
Amnesia
All 26 patients remembered the first
symbol; 69% remembered the symbol shown at 30 minutes; 50% remembered the 60 minute
symbol;40% remembered the symbol shown half-way through the appointment and 32%
remembered the symbol shown at the conclusion of treatment. The narratives written
by patients tend to agree with the amnesia reported with the symbols, 30% remembering
the injection which occurred at 60 minutes. Only one patient recalled the whole
appointment. Most remembered only small portions of it. A small control group
of 3, all normal patients requiring no sedation for dentistry, remembered all
5 symbols.
Cardiovascular-respiratory parameters
Cardiovascular parameters had small
changes. The systolic blood pressure fell 9% from a preoperative mean of 124 mmHg
- SD l7.6 to 120 mmHg - SD 16.5 at 15 minutes and 117 mmHg - SD 116.7 from 30
minutes to completion. The diastolic blood pressure fell 7% from 79 mmHg - SD
11.7 mean preoperatively to 77.9-76.9 mmHg SD 14.5 - 9.5 from 15 minutes to completion.
The heart rate fell from 91.3 beats per minute SD 21.1 to 89.7 SD 19.1 at 15 minutes,
fell to 89.0 - SD 18.0 at 30 minutes, climbed to 91.4 SD 20.1 at 45 minutes and
climbed to 94.3 - SD 20.7 after the injection of local anesthesia. Haemoglobin-oxygen
saturation remained stable at 95.4 - 96.1 % for the whole procedure. End tidal
carbon dioxide levels were monitored on the last 11 patients and recorded; it
varied from 33.6 mmHg SD 2.7 to 35.0 - SD 2.76.
Dosages
Early dosages derived from reports in
the literature for sleep enhancement proved inadequate for our purposes; 16 patients
required additional drug. When dose in mg. and weight in pounds is compared with
operator's assessment of level of sedation, a trend emerged indicating that the
appropriate initial dosage could be determined by the following equation:
Dose in mg. = 0.25 mg + 0.125 mg. for every 70 pound weight increment over 40
pounds. In the case of children under 40 pounds, the first treatment was attempted
with 0.125 mg. In most cases this dose was ineffective. The mean dosage was 0.0042
mg per pound (SD 0.0022 mg per pound) with a range of 0.00083 to 0.108 mg per
pound.
Discussion
It should be emphasized that this study
was conducted coincidentally to the patient's treatment in a private practice.
The technique described and the parameters evaluated evolved with drug familiarity.
As questions arose, the study was expanded to investigate these areas.
With the increased cost of malpractice
insurance, it is difficult to justify the use of IV agents for the occasional
sedation patient. Oral medication is an alternative. Determining dosage of drug
early in the study was difficult. Many of the amnesia failures, higher levels
of apprehension and lack of sedation which occurred were with patients who were
undersedated because of a lack of knowledge as to what constituted an adequate
dose. A much larger study is needed to confirm our findings.
Status of Triazolam
Upjohn
The Upjohn company distributes triazolam
(Halcion) in the U.S. They make no claims of its usefulness as a dental sedative,
nor has it been tested for use with children. The UpJohn company made it very
clear to me in a letter that its use for dental sedation and with children is
investigational in nature and not supported or encouraged by the company.
Food and Drug Administration (FDA)
The Food and Drug Administration does
not recognize triazolam's use for either dental or pediatric sedation. A practitioner
must recognize that should there be a problem, the lack of FDA approval would
create problems from a medical-legal standpoint. Lack of FDA approval does not,
however, prevent our using the drug for sedation.
Recordkeeping requirements
The Drug Enforcement Administration,
a division of the U.S. Department of Justice, has a booklet that is available
from any DEA office entitled, Physician's Manual, An Informational Outline of
the Controlled Substances Act of 1970. This manual spells out the requirements
of recordkeeping, storage, inventory, security, etc. required for prescribing
and dispensing a controlled substance. triazolam is a schedule IV substance. Schedule
IV substances "have an abuse potential less than those listed in Schedule III
and include such drugs as barbital, phenobarbital ... chloral hydrate ... Meprobamate
... diazepam (Valium) ... alprazolam (Xanax) ... triazolam (triazolam) ... lorazepam
(Ativan) ... medazolam (Versed) ... "
To administer, prescribe or dispense
any controlled substance a physician (dentist) must be registered with the DEA.
"The registration must be renewed every three years and the certificate of registration
must be maintained at the registered location."
"It is necessary for dentists to
keep records of drugs purchased, distributed and dispensed. Having this closed
system, a controlled substance can be traced from the time it is manufactured
to the time it is dispensed to the ultimate user."
"All controlled substance records
must be filed in a readily retrievable manner from all other business documents,
retained for two years and made available for inspection by DEA. Controlled
substance records maintained as part of the patient file will require that this
file be made available for inspection by DEA."
"A physician (dentist) who dispenses
controlled substances is required to keep a record of each transaction." "(Dispense
means to deliver a controlled substance in some type of bottle, box or other
container to a patient. Under these acts the definition of dispense also includes
the administering of a controlled substance.)"
"A physician (dentist) who regularly
engages in administering controlled substances in Schedule II, III, IV and V
is required to keep records if patients are charged for these drugs either separately
or together with other professional services. When a physician dispenses a controlled
substance and administers this substance occasionally or regularly from the
same inventory, the physician (dentist) must keep a record of all transactions."
"Administer means to instill a drug into the body of a patient."
Inventory requirements
"A physician (dentist) who dispenses
or regularly engages in administering controlled substances and is required to
keep records as stated above must take an inventory every two years of all stocks
of the substances on hand." An inventory of all stocks must be on hand on the
date when the use of controlled substances began. "In the event no controlled
substances are on hand at the initial inventory, a zero inventory should be recorded."
'The inventory record must:
- List the name, address and DEA
registration number of the registrant.
- Indicate the date and time the
inventory is taken. i.e., opening or close of business.
- Be signed by the person or persons
responsible for taking the inventory.
- Be maintained at the location
appearing on the registration certificate for at least two years.
- Keep records of schedule II drugs
separate from all other controlled substance records."
"All inventories and records of controlled
substances in Schedule IV must be maintained separately or must be in such form
that they are readily retrievable from the ordinary professional and business
records of the physician (dentist)."
Security
"A physician (dentist) who has controlled
substances stored in an office or clinic must keep these drugs in a securely locked,
substantially constructed cabinet or safe. "
"It is recommended that the controlled substance stock be kept to a minimum."
In my office, the triazolam is kept locked in a key locker which is permanently
attached to an office wall. Inventory sheets are kept in a book with patient record
forms. This sheet shows date, patient name, age, weight and has space for comments.
The inventory total is changed with each drug administration so as to provide
a running total of the drug inventory. When restocking the drug supply, a copy
of the prescription is attached to the inventory sheet.
Patient records
Patient records are kept for all treatments.
They include blood pressure records, pulse rates and pulse oximeter readings.
These records are taken and recorded preoperatively and at 15 minute increments
from the the drug administration until the case is completed. In addition, the
patient reports their level of apprehension preoperatively at 30 minutes, at the
start of the procedure (60 minutes), midway through the procedure, and at the
close of the procedure. The patient's medical status (ASA rating) is recorded
along with their age, sex, weight, amounts of drug administered, name date and
whether this is the first administration of this sedative.
Our sedation records are necessary
for several reasons. First, they establish a baseline and would be one of the
first indicators of a potential problem. If any of the parameters measured start
to change, we should immediately be alerted to this possibility and start corrective
action. Second, the stress of an emergency makes time sequencing difficult for
the practitioner. It becomes all but impossible to recall vital signs and the
times they were recorded. Complete records can provide clues about the case
and possible solutions to our problem as it progresses. (At what point did we
lose verbal contact? How long has the patient been at this level? Did the change
come on rapidly or have vital signs been slowly changing for some time?) Lastly,
in the event of legal action, complete and accurate records are a must for one's
defense.
Case reports
The reports presented are of my own
patients or were reported to me by other practitioners. They represent over 200
cases of sedation and are presented to illustrate the types of problems we have
seen and how they were controlled.
The worst case scenario for most
sedation is a respiratory depression and/or respiratory obstruction. In this
worst case, a patient's exchange of gasses is inadequate to carry adequate O2
to the blood or remove CO2. The levels of O2 in the arterial blood
would fall as would the O2 perfussion to tissues, particularly the
brain. This depression would allow an increase in CO2 levels and
thus a lowering of the pH of the blood. Triazolam has shown very little tendency
to depress respiration or affect circulation. Generally speaking, however, and
to reiterate my earlier comments, I am concerned when someone tends to sleep
since if they are not awake, how do we know if they are under general anesthesia?
The most common occurrence precipitating an anesthesia emergency is respiratory
insufficiency. For this reason I am more comfortable when working on a conscious
patient who is being monitored by a pulse oximeter with the alarm set to go
off for any reading below 90% saturation.
Patient No. 1
The first case report is a 34 year old
black female ASA 1. She was moderately overweight and had a rather short neck.
She had worked the night before her appointment in a manufacturing plant and had
been about 36 hours without sleep. I administered our usual dose for her weight.
Thirty (30) minutes later she was noticeably more relaxed. We started her dentistry
at 45 minutes and did operative dentistry for about 1 hour. She did fine. Her
blood pressure, pulse rate, and respiration were normal. Her pulse oximeters reading
ranged between 93 - 97%. At the close of the procedure she tended to sleep if
we did not keep talking to her. Several times her head would drop on her chest
and she would partially occlude her airway and snore. At these times her SAO2
would slowly fall to 87% over several minutes and she would then take a deep breath
and return the saturation to the 93-97% range. We kept her in the dental chair
for the next hour until she stopped obstructing and was noticeably less sedated.
Her husband took her home with instructions to watch her and call if she had any
problems. I called and checked on her several times that evening. She did fine.
I was concerned about her obstructing her airway because of her body weight and
short neck. Her husband reported that she normally snored when she slept.
Patient No. 2
The second patient was a 40 year old
white female. She had been an IV patient for a number of years because of her
dental phobia. She was given a modest dose of triazolam. She was noticeably relaxed
by 30 minutes and we started her procedure at the 45 minute point. She tended
to sleep if left unstimulated but would open her eyes and follow directions if
she was spoken to. Her oxygen saturation stayed greater than 95%, her blood pressure
and pulse rate stayed constant at pre-operative levels. We kept her in the dental
office an extra hour and by that time she was staying awake. She was dismissed
to an adult with directions to keep her awake and call if there were any problems.
Patient No. 3
The third patient was a 15 month old,
25 pound Asian female, a recent immigrant who had severe baby bottle caries. Our
oral exam was very difficult and was confined to a simple visual exam. We attempted
to treat her with 0.125 mg of triazolam as she was nearly uncontrollable. The
treatment was somewhat complicated by her lack of understanding of English. We
had a parent in the operatory to translate; however, little communication took
place due to her age, and lack of control. For the second appointment we used
0.25 mg. of triazolam. She cried and moved some during treatment, but we were
able to complete several stainless steel crowns. At the close of the appointment,
100 minutes after administering the drug, she tended to sleep although would awaken
if verbally stimulated. Her pulse rate stayed constant at the pre-op levels and
her O2 saturation stayed greater than 95% without supplemental oxygen.
If left alone, however, she laid very still and slept. Two and a half (2 1/2)
hours after drug administration she sat up and told her father she wanted to go
home. We again gave directions to observe her the rest of the afternoon and call
if she did not stay awake. Her father reported that she went home and watched
TV without sleeping.
Patient No. 4
A seven year old was sedated for dental
treatment by a pediatric dentist. The patient left the office able to walk holding
the hand of her mother. She went home and tended to sleep if left alone. The dentist's
home phone line was out of order that evening. After trying to reach the dentist,
her mother became concerned and called a local emergency room who told her to
watch the patient and that triazolam was not approved for use with children. The
mother then called poison control and was again told that triazolam should not
be used with children. The dentist relieved the mother's concerns when she reached
him in the office the next day.
Patient No. 5
A 40 year old black male about 6'1"
tall and 230 pounds had an uneventful sedation. At the close of the case, when
he was judged to be ready to leave, his wife, a rather petite woman of 5'6," was
brought in and given post-op instructions. At this time she mentioned they would
be taking a public bus home. Because I was concerned about her being able to help
the patient on and off the bus, we kept him an extra hour to assure us that his
wife would not have any problem getting him home. We did not insist that the patient
be transported by auto.
Flamezinal
It would be a great advantage to have
a drug that would reverse the effects of any drug we use. This is particularly
true of any drug that requires excretion or metabolism to be deactivated. When
using drugs intravenously, small test doses can be given and augmented as necessary
to achieve the desired effect. These test doses go directly to the CNS and show
their effect. They are then redistributed to the rest of the tissues of the body,
effectively diluting the effect in the case of an overdose or sensitivity to an
agent. Because it is impossible to titrate for effect when using oral drugs, it
takes a considerable time before it is obvious we have a problem and redistribution
and saturation of the other tissues has already taken place and are of little
aid. In the case of overdose, there is little we can do except treat the symptoms
of the overdose, and support respiration and circulation. For this reason, a reversal
agent for oral drugs is very desirable.
History
In 1974, Haefely hypothesized that benzodiazepines
act by increasing the effectiveness of the most important inhibitory neurotransmitter,
GABA. In 1976 it was shown that diazepam bound selectively to certain brain proteins
at the benzodiazepine receptor sites and that they made GABA more effective. They
produced several compounds that had a greater affinity for this site than diazepam.
One of these, flamezinal, was selected in 1979 as an antagonist for clinical trials.
In early 1992, the Hoffman La Rouche
company introduced to the U.S. market a benzodiazepine reversal agent, Mazicon,
flumazenil, ethyl 6-fluoro-6, 6-dihydro-5-methyl-6-oxo-4h-imidazo (l,5-a)(1,4)
benzodiazepine-3-carboxylate. This agent has been in use in other parts of the
world for some time and has proven very important in treating overdoses and
reversing the effects of benzodiazepine. Flumazenil displaces benzodiazepine
drugs from their receptor site, reversing their sedative action.
Normal dosages of this drug are
reported to be 0.007 and 0.014 mg/kg. The lethal dose in mice and rats is 62.5
and 125 mg/kg. Another study suggested that 3000 times the therapeutic dose
could be given with only minor effects. It has been tested up to 200 mg. given
IV and orally. In the case of oral dosages, only 18% are active as it is oxidized
in the first pass through the liver.
The following quotation is from
a letter from M. L. Bergamo, M.D., Assistant Director, Professional Services,
Roache Laboratories, dated February 27, 1992. "Flumazenil is indicated for the
complete or partial reversal of the sedative effects of benzodiazepines in cases
where general anesthesia has been induced and/or maintained with benzodiazepines,
where sedation has been produced with benzodiazepines for diagnostic and therapeutic
procedures, and for the management of benzodiazepine overdose."
"Doses of approximately 0.1 to 0.2 mg (corresponding to peak plasma levels of
3 to 6 ng/mL) produce antagonism, whereas higher doses of 0.4 to 1.0 mg (peak
plasma levels of 12 to 28 mg/mL) usually produce complete antagonism in patients
that have received the usual sedating doses of benzodiazepines. The onset of
reversal is usually evident within one to two minutes, with peak effects occurring
six to ten minutes after a single intravenous injection. The duration and degree
of reversal is also related to the plasma concentration of the sedating benzodiazepine."
"Most patients with benzodiazepine
overdose will respond to a cumulative dose of 1 to 3 mg of flumazenil and doses
beyond 3 mg do not reliably produce additional effects. On rare occasions, patients
with a partial response at 3.0 mg may require additional titration up to a total
dose of 5.0 mg."
"If a patient has not responded
5 minutes after receiving a cumulative dose of 5 mg, the major cause of sedation
is likely not to be due to benzodiazepines. ... In management of suspected overdose,
497 patients received flumazenil, 299 proved to have taken a benzodiazepine,
83% responded by an improvement in the level of consciousness. 77% responded
to a total dose of 1.0 to 3.0 mg. "
"In the event of resedation repeated
doses may be given at 20 minute intervals if needed. For repeat treatment, no
more than 1.0 (given as 0.5 mg/min) should be given at any one time and no more
than 3.0 mg should be given in any one hour."
"In the overdose treated patient,
reversal of sedation was associated with an increased frequency of symptoms
of CNS excitation (agitation or anxiety) which were treated in 1% to 3% of the
cases. Serious side effects were uncommon, but six seizures were observed in
446 patients treated with Mazicon in these studies. Four of the six patients
who experienced seizures had ingested a large dose of cyclic antidepressants."
"Resedation has been observed in
1% to 3% of the patients in the clinical trials. Resedation is least likely
in cases where Mazicon is given to reverse a low dose of a short-acting benzodiazepine
(<10 mg midazolam), and most likely in cases where a large single or cumulative
dose of a benzodiazepine has been given in the course of a long procedure along
with neuromuscular blocking agents and multiple anaesthetic agents."
Adverse effects
"The most frequently associated adverse
events reported during clinical trials were nausea, vomiting, dizziness (vertigo,
ataxia), agitation (anxiety, nervousness), emotional lability (euphoria, abnormal
crying, abnormal tears), cutaneous vasodilation (sweating, flushing, hot flashes),
injection site pain, injection site reaction, fatigue (asthenia, malaise), abnormal
vision (visual field defect, diplopia), hyposthesia (sensation abnormal, paresthesia),
and headache."
Mechanism of Action
Flumazenil competitively interacts with
other benzodiazepine drugs at the GABA "chloride channel receptor sites in the
CNS, particularly in the cortex, limbic lobe, and spinal cord. It has no effect
on peripheral receptors."
Metabolism
"Flumazenil is quickly and completely
metabolized in the liver by hepatic microsomal oxidation." It is converted into
inactive acid or glucuronide metabolites. "Less than 0.2% is excreted unchanged
in the urine.
Pharmacokinetics
The absorption half-life of oral flumazenil
is about 0.3 hours. Peak plasma concentrations occurred 20 to 90 minutes after
administration. When given orally the drug is absorbed from the GI system and
passes via the portal circulation through the liver before becoming available
to the CNS. Only about 16% becomes available to the circulatory system. 200 mg
oral doses gave similar blood levels as 40 mg doses given intravenously. Rapid
uptake by the brain has been shown to be a 3:1 ratio brain-to-blood. It has been
shown to be distributed by the cerebral vasculature and taken up by gray-matter
structures within 1 to 2 minutes if given intravenously. Maximal cerebral concentrations
are attained in 5 to 8 minutes. Binding was greatest in the medial-occipital cerebral
cortex and to a lesser extent in the cerebellum and pons. It conformed to the
GABA receptor sites of the brain and was cleared from the body in 4 hours.
Pharmacology
Flumazenil was shown to prevent benzodiazepine
sedation if given before the benzodiazepine and to reverse the effect if given
during or after the sedative drug. To reverse sedation or general anesthesia of
benzodiazepine drugs, flumazenil is administered intravenously in titrated doses
from 0.2 to 1.0 mg doses. In the case of overdose, 2.0 to 3.0 mg may be necessary.
Toxicity and safety
"Flumazenil has a high therapeutic index
and a wide margin of safety." It showed minimal effect on patients with ischemic
heart disease. No withdrawal symptoms were seen when given to patients who had
been on diazepam or triazolam for up to 14 days. Some symptoms were seen in patients
who had been on loraxepam. It should not be given to patients with severe head
injuries and unstable intracranial pressures. When given to patients with panic
disorder, 2 mg of flumazenil intravenously precipitated panic attacks. It had
no effect on healthy patients.
Use with children
Jones administered flumazenil to 40
healthy children aged 3-12 years of age after they had received 0.5 mg per kg
orally for premedication and 0.5 mg per kg intravenously for induction of anesthesia.
The drug was given along with a placebo and the efficacy of antagonism was assessed.
After surgery they were given 0.1 ml (.001mg. of agent) per kg of solution followed
by 0.05 ml. (0.0005 mg of agent) per mg per minute until they were either awake
or 10 ml. (1 mg of agent) had been administered intravenously. Each 10 ml. of
solution contained 1 mg. of flumazenil. Those receiving the active drug awoke
approximately four times faster. The mean total dose of flumazenil administered
was 0.024 mg per kg (SD 0.019 mg per kg). There were no cases of resedation and
minimal changes in the cardio-respiratory variables.
Use with adults
The half-life of flumazenil at 54 (.7
to 1.3 hr, 50 min. average) minutes is less than midazolam and diazepam so you
may see some rebound of effect and may need follow-up doses. Sedation was gone
within 2 to 5 minutes. One author saw no improvement after 15 minutes, others
showed improvement at 15 and 30 but not 60 minutes. One (1) mg will last for about
2 hours. Flumazenil is rapidly eliminated by the liver. Side effects are infrequent
but include mild headache, loss of pupil reactivity to light and mild hypotension.
Contraindications
Flumazenil is contra indicated in patients
with a known hypersensitivity to flumazenil or to benzodiazepines, in patients
who have been given a benzodiazepine for control of a potentially life-threatening
condition (e.g. control of intracranial pressure or status epilepticus), and in
patients who are showing signs of serious cyclic antidepressant overdose.
Resedation
Because of the relatively short half
life of flumazenil, 0.8 to 1.6 hours, it is possible that its reversal effect
could disappear before the sedative effect of triazolam with its half-life 1-2
hours. Midazolam has a similar half-life (1-2 hours) and several studies have
failed to show significant resedation if appropriate doses of midazolam had been
used. Resedation has been shown with diazepam which has a much longer half-life
(20-50 hours) and with larger doses of midazolam. Until studies have been reported
showing no resedation with triazolam, a patient who requires flumazenil should
be observed for several hours after reversal to be positive resedation does not
occur. There is a risk that with reversal the patient may feel normal and attempt
activities they are not capable of safely performing.
With the introduction of this reversal
agent, we will be able to use triazolam with the comfort of knowing that we
should be able to reverse its sedation should we achieve an overdose. Of course,
this in no way should cause us to use excessive doses of triazolam, nor does
it relieve us of the responsibility of monitoring a patient's physical status
and responding accordingly in the case of cardiovascular or respiratory depression.
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