Overdose
Hemodynamic Effects
The effects of nitroglycerin overdose are generally the
results of nitroglycerin's capacity to induce vasodilatation, venous pooling,
reduced cardiac output, and hypotension. These hemodynamic changes may have
protean manifestations, including increased intracranial pressure, with any or
all of persistent throbbing headache, confusion, and moderate fever; vertigo;
palpitations; tachycardia; visual disturbances; nausea and vomiting (possibly
with colic and even bloody diarrhea); syncope (especially in the upright posture);
dyspnea, later followed by reduced ventilatory effort; diaphoresis, with the
skin either flushed or cold and clammy; heart block and bradycardia; paralysis;
coma; seizures; and death.
No specific antagonist to the vasodilator effects of
nitroglycerin is known, and no intervention has been subject to controlled
study as a therapy of nitroglycerin overdose. Because the hypotension
associated with nitroglycerin overdose is the result of venodilatation and
arterial hypovolemia, prudent therapy in this situation should be directed
toward increase in central fluid volume. Passive elevation of the patient's legs
may be sufficient, but intravenous infusion of normal saline or similar fluid
may also be necessary.
The use of epinephrine or other arterial vasoconstrictors
in this setting is likely to do more harm than good.
In patients with renal disease or congestive heart
failure, therapy resulting in central volume expansion is not without hazard.
Treatment of nitroglycerin overdose in these patients may be subtle and
difficult, and invasive monitoring may be required.
Methemoglobinemia
Methemoglobinemia has been rarely reported in association
with organic nitrates. The diagnosis should be suspected in patients who
exhibit signs of impaired oxygen delivery despite adequate cardiac output and
adequate arterial PO2. Classically, methemoglobinemic blood is described as
chocolate brown, without color change on exposure to air.
If methemoglobinemia is present, intravenous
administration of methylene blue, 1 to 2 mg/kg of body weight, may be required.
Contraindications
Allergic reactions to organic nitrates are extremely
rare, but they do occur. Nitroglycerin is contraindicated in patients who are
allergic to it.
Sublingual nitroglycerin therapy is contraindicated in
patients with early myocardial infarction, severe anemia, increased
intracranial pressure, and those with a known hypersensitivity to
nitroglycerin.
Administration of NITROSTAT is contraindicated in
patients who are using a phosphodiesterase-5 (PDE-5) inhibitor (e.g.,
sildenafil citrate, tadalafil, vardenafil hydrochloride) since these compounds
have been shown to potentiate the hypotensive effects of organic nitrates.
Undesirable effects
Headache that may be severe and persistent may occur
immediately after use. Vertigo, dizziness, weakness, palpitation, and other manifestations
of postural hypotension may develop occasionally, particularly in erect,
immobile patients. Marked sensitivity to the hypotensive effects of nitrates
(manifested by nausea, vomiting, weakness, diaphoresis, pallor, and collapse)
may occur at therapeutic doses. Syncope due to nitrate vasodilatation has been
reported. Flushing, drug rash, and exfoliative dermatitis have been reported in
patients receiving nitrate therapy.
Therapeutic indications
Nitroglycerin is indicated for the acute relief of an
attack or acute prophylaxis of angina pectoris due to coronary artery disease.
Date of revision of the text
March 2014
Qualitative and quantitative composition
NITROSTAT is supplied as white, round, flat-faced tablets
in 3 strengths (0.3 mg, 0.4 mg, and 0.6 mg) in bottles containing 100 tablets each,
with color-coded labels, and in color-coded Patient Convenience Packages of 4
bottles of 25 tablets each.
0.3 mg: Coded “N” on one side and
“3” on the other.
NDC 0071-0417-24—Bottle of 100 tablets
0.4 mg: Coded “N” on one side and
“4” on the other.
NDC 0071-0418-13—Convenience Package
NDC 0071-0418-24—Bottle of 100 tablets
0.6 mg: Coded “N” on one side and
“6” on the other.
NDC 0071-0419-24—Bottle of 100 tablets
Store at Controlled Room Temperature 20°–25°C (68°–77°F)
.
Distributed by: Parke-Davis, Division of Pfizer Inc., NY,
NY 10017. Revised: March 2014
Special warnings and precautions for use
WARNINGS
The benefits of sublingual nitroglycerin in patients with
acute myocardial infarction or congestive heart failure have not been
established. If one elects to use nitroglycerin in these conditions, careful clinical
or hemodynamic monitoring must be used because of the possibility of hypotension
and tachycardia.
PRECAUTIONS
General
Only the smallest dose required for effective relief of
the acute anginal attack should be used. Excessive use may lead to the development
of tolerance. NITROSTAT tablets are intended for sublingual or buccal
administration and should not be swallowed.
Severe hypotension, particularly with upright posture,
may occur with small doses of nitroglycerin. This drug should therefore be used
with caution in patients who may be volume-depleted or who, for whatever
reason, are already hypotensive. Hypotension induced by nitroglycerin may be
accompanied by paradoxical bradycardia and increased angina pectoris.
Nitrate therapy may aggravate the angina caused by
hypertrophic cardiomyopathy.
As tolerance to other forms of nitroglycerin develops,
the effects of sublingual nitroglycerin on exercise tolerance, although still
observable, is blunted.
In industrial workers who have had long-term exposure to
unknown (presumably high) doses of organic nitrates, tolerance rarely occurs. Chest
pain, acute myocardial infarction, and even sudden death have occurred during
temporary withdrawal of nitrates from these workers, demonstrating the
existence of true physical dependence.
Several clinical trials of nitroglycerin patches or
infusions in patients with angina pectoris have evaluated regimens that
incorporated a 10- to 12-hour nitrate free interval. In some of these trials,
an increase in the frequency of anginal attacks during the nitrate free
interval was observed in a small number of patients. In one trial, patients had
decreased exercise tolerance at the end of the nitrate interval. Hemodynamic
rebound has been observed only rarely; on the other hand, few studies were so
designed that rebound, if it had occurred, would have been detected.
Nitrate tolerance as a result of sublingual nitroglycerin
administration is probably possible, but only in patients who maintain high continuous
nitrate levels for more than 10 or 12 hours daily. Such use of sublingual
nitroglycerin would entail administration of scores of tablets daily and is not
recommended.
The drug should be discontinued if blurring of vision or
drying of the mouth occurs. Excessive dosage of nitroglycerin may produce
severe headaches.
Information For Patients
NITROSTAT is a sublingual tablet and should not be
chewed, crushed, or swallowed.
If possible, patients should sit down when taking
NITROSTAT tablets and should use caution when returning to a standing position.
This eliminates the possibility of falling due to lightheadedness or dizziness.
One tablet should be dissolved under the tongue or in the
buccal pouch at the first sign of an acute anginal attack. The dose may be
repeated approximately every 5 minutes until relief is obtained.
If chest pain persists after a total of 3 tablets in a
15-minute period, or if the pain is different than is typically experienced,
prompt medical attention is recommended.
NITROSTAT may be used prophylactically 5 to 10 minutes
prior to engaging in activities that might precipitate an acute attack.
Nitroglycerin may produce a burning or tingling sensation
when administered sublingually; however, the ability to produce a burning or tingling
sensation should not be considered a reliable method for determining the
potency of the tablets.
Headaches can sometimes accompany treatment with
nitroglycerin. In patients who get these headaches, the headaches may be a
marker of the activity of the drug.
Treatment with nitroglycerin may be associated with
lightheadedness upon standing, especially just after rising from a recumbent or
seated position. This effect may be more frequent in patients who have also
consumed alcohol.
Nitroglycerin should be kept in the original glass container
and must be tightly capped after each use to prevent loss of tablet potency.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Animal carcinogenesis studies with sublingually
administered nitroglycerin have not been performed.
Carcinogenicity potential of nitroglycerin was evaluated
in rats receiving up to 434 mg/kg/day of dietary nitroglycerin for 2 years.
Rats developed dose-related fibrotic and neoplastic changes in liver, including
carcinomas, and interstitial cell tumors in testes. At high dose, the incidences
of hepatocellular carcinomas in males was 48% and in females was 33%, compared
to 0% in untreated controls. Incidences of testicular tumors were 52% vs. 8% in
controls. Lifetime dietary administration of up to 1058 mg/kg/day of
nitroglycerin was not tumorigenic in mice.
Nitroglycerin was mutagenic in Ames tests performed in 2
different laboratories. Nevertheless, there was no evidence of mutagenicity in
an in vivo dominant lethal assay with male rats treated with doses up to about
363 mg/kg/day, PO, or in ex vivo cytogenetic tests in rat and dog cells.
In a 3-generation reproduction study, rats received
dietary nitroglycerin at doses up to about 434 mg/kg/day for 6 months prior to
mating of the F generation, with treatment continuing through successive F and
F generations. The high dose was associated with decreased feed intake and body
weight gain in both sexes at all matings. No specific effect on the fertility
of the F generation was seen. Infertility noted in subsequent generations,
however, was attributed to increased interstitial cell tissue and
aspermatogenesis in the high-dose males. In this 3- generation study, there was
no clear evidence of teratogenicity.
Pregnancy Category B
Animal reproduction and teratogenicity studies have not
been conducted with nitroglycerin sublingual tablets. However, teratology
studies conducted in rats and rabbits with topically applied nitroglycerin
ointment at dosages up to 80 mg/kg/day and 240 mg/kg/day, respectively revealed
no toxic effects on dams or fetuses.
There are no adequate and well-controlled studies in
pregnant women. Nitroglycerin should be given to a pregnant woman only if
clearly needed.
Nursing Mothers
It is not known whether nitroglycerin is excreted in
human milk. Because many drugs are excreted in human milk, caution should be exercised
when nitroglycerin is administered to a nursing woman.
Pediatric Use
The safety and effectiveness of nitroglycerin in
pediatric patients have not been established.
Geriatric Use
Clinical studies of NITROSTAT did not include sufficient
numbers of subjects aged 65 and over to determine whether they respond differently
from younger subjects. Other reported clinical experience has not identified
differences in responses between the elderly and younger patients. In general,
dose selection for an elderly patient should be cautious, usually starting at
the low end of the dosing range, reflecting the greater frequency of decreased
hepatic, renal, or cardiac function, and of concomitant disease or other drug
therapy.
Dosage (Posology) and method of administration
One tablet should be dissolved under the tongue or in the
buccal pouch at the first sign of an acute anginal attack. The dose may be
repeated approximately every 5 minutes until relief is obtained. If the pain
persists after a total of 3 tablets in a 15-minute period, or if the pain is different
than is typically experienced, prompt medical attention is recommended.
NITROSTAT may be used prophylactically 5 to 10 minutes prior to engaging in
activities that might precipitate an acute attack.
During administration the patient should rest, preferably
in the sitting position.
No dosage adjustment is required in patients with renal
failure.
Interaction with other medicinal products and other forms of interaction
SIDE EFFECTS
Headache that may be severe and persistent may occur
immediately after use. Vertigo, dizziness, weakness, palpitation, and other manifestations
of postural hypotension may develop occasionally, particularly in erect,
immobile patients. Marked sensitivity to the hypotensive effects of nitrates
(manifested by nausea, vomiting, weakness, diaphoresis, pallor, and collapse)
may occur at therapeutic doses. Syncope due to nitrate vasodilatation has been
reported. Flushing, drug rash, and exfoliative dermatitis have been reported in
patients receiving nitrate therapy.
DRUG INTERACTIONS
Concomitant use of nitrates and alcohol may cause
hypotension.
The vasodilatory and hemodynamic effects of nitroglycerin
may be enhanced by concomitant administration of aspirin.
Intravenous administration of nitroglycerin decreases the
thrombolytic effect of alteplase. Therefore, caution should be observed in
patients receiving sublingual nitroglycerin during alteplase therapy.
Intravenous nitroglycerin reduces the anticoagulant
effect of heparin and activated partial thromboplastin times (APTT) should be monitored
in patients receiving heparin and intravenous nitroglycerin. It is not known if
this effect occurs following single sublingual nitroglycerin doses.
Tricyclic antidepressants (amitriptyline, desipramine,
doxepin, others) and anticholinergic drugs may cause dry mouth and diminished salivary
secretions. This may make dissolution of sublingual nitroglycerin difficult.
Increasing salivation with chewing gum or artificial saliva products may prove
useful in aiding dissolution of sublingual nitroglycerin.
Oral administration of nitroglycerin markedly decreases
the first-pass metabolism of dihydroergotamine and subsequently increases its
oral bioavailability. Ergotamine is known to precipitate angina pectoris.
Therefore, patients receiving sublingual nitroglycerin should avoid ergotamine
and related drugs or be monitored for symptoms of ergotism if this is not
possible.
Administration of nitroglycerin is contraindicated in
patients who are using PDE-5 inhibitors (e.g., sildenafil citrate, tadalafil,
vardenafil hydrochloride). These compounds have been shown to potentiate the
hypotensive effects of organic nitrates.
A decrease in therapeutic effect of sublingual
nitroglycerin may result from use of long-acting nitrates.
Drug/Laboratory Test Interactions
Nitrates may interfere with the Zlatkis-Zak color
reaction, causing a false report of decreased serum cholesterol.