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FDA Public Health Advisory
Benzocaine Sprays marketed under different names,
including Hurricaine, Topex, and Cetacaine
1
Benzocaine sprays are used in medical practice for locally numbing
mucous membranes of the mouth and throat for minor surgical procedures
or when a tube must be inserted into the stomach or airways.
Their use is known to be occasionally associated with
methemoglobinemia. However, cases of methemoglobinemia have also
resulted from medication errors due to incorrect use of benzocaine
sprays (e.g., longer duration or more frequent sprays than
recommended.). On February 8, 2006, the Veterans Health
Administration (VA) announced the decision to stop using benzocaine
sprays for these purposes. The FDA is aware of the reported
adverse events and is reviewing all available safety data, but at this
time is not planning action to remove the drugs from the market.
Up until now, the FDA has concluded that the number of reported
adverse events with these sprays has been low and, when properly used,
these products can help make important procedures less uncomfortable
for patients. This advisory applies only to
benzocaine sprays used in the mouth and throat,
not to other benzocaine products or to benzocaine
sprays applied to exterior skin.
The FDA is again highlighting here safety information previously
addressed by the Agency (see
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/psn/printer.cfm?id=40
), and will make further announcements or take action as warranted by
the ongoing review. At present, the FDA suggests considering the
following points about the use of benzocaine sprays in procedures
requiring that a tube be inserted in the larynx or pharynx (down the
throat, windpipe, or gullet) or in minor surgical procedures performed
in these locations.
Considerations
- Benzocaine sprays used in the mouth and throat can result in
potentially dangerous levels of methemoglobinemia.
- Patients who have breathing problems such as asthma, bronchitis,
or emphysema, patients with heart disease, and patients who smoke
are at greater risk for complications related to methemoglobinemia
and may be candidates for other forms of therapy.
- Patients who may have greater tendency for elevated levels of
methemoglobinemia, such as all children less than 4 months of age
and older patients with certain in-born defects (such as
glucose-6-phosphodiesterase (G-6-PD) deficiency, hemoglobin-M
disease, NADH-methemoglobin reductase (diaphorase 1) deficiency, and
pyruvate-kinase deficiency) may benefit from products with different
active ingredients such as lidocaine.
- Patients who receive benzocaine sprays should be given the
minimum amount needed, to reduce the risks associated with
methemoglobinemia.
- Patients who receive benzocaine sprays should be carefully
observed for signs of methemoglobinemia including pale, gray or blue
colored skin, headache, lightheadedness, shortness of breath,
anxiety, fatigue and tachycardia (rapid heart rate).
- Methemoglobinemia makes a standard device used to assess the
amount of oxygen bound to hemoglobin (2-wavelength pulse oximetry)
unreliable. If blood is drawn to check for the condition, a
co-oximeter is needed to reliably detect methemoglobinemia.
- A characteristic color of the blood (chocolate-brown rather than
blood-red) can be a danger sign, but these changes are a late sign
of the condition.
- Patients suspected of having high levels of methemoglobinemia
should be promptly treated.
Methemoglobinemia is a condition where too much of the hemoglobin
in red blood cells becomes unable to bind and carry oxygen.
While there is treatment available, until the condition is reversed,
oxygen is not effectively delivered throughout the patient’s body.
Patients with methemoglobinemia can suffer effects ranging from
headache to cyanosis (turning blue due to lack of oxygen) that can be
life-threatening in the most severe cases. Patients with
underlying breathing problems, such as asthma or emphysema, patients
with heart disease, and those who smoke may be more susceptible to the
problems from methemoglobinemia and may suffer from bad effects from
this condition at lower levels of methemoglobin than healthy
individuals. Similarly, some patients may lack or have reduced
level of enzymes that help reverse the methemoglobinemia, and they are
also more susceptible to risks associated with benzocaine sprays.
The VA health system has announced its decision to remove
benzocaine sprays from their practice because they believe other
topical anesthetics are less likely to cause methemoglobinemia and
because the procedures themselves might cause similar signs,
suggesting that methemoglobinemia may occur but go unrecognized in
some cases. The FDA has received adverse event reports involving
benzocaine sprays together with symptoms that probably indicated
methemoglobinemia in the patients. It is important to note also
that these cases were received over a period of many years and this is
an uncommon adverse event. The FDA is continuing to review
all available safety information for these affected products.
1 In addition to benzocaine,
Cetacaine® also contains butyl aminobenzoate and tetracaine as active
ingredients.
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Date created: February 10, 2006 |
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