End the ice age - Is glacial acetic acid really needed?
From the May 5, 2005
"POISON! DANGER! CORROSIVE. Liquid And Mist
Cause Severe Burns To All Body Tissue. May Be Fatal If Swallowed.
Harmful If Inhaled. Inhalation May Cause Lung And Tooth Damage."
Problem: That's exactly what it says in the warning
statements next to the red skull and crossbones on the label
of glacial acetic acid (pure acetic acid). Still, as strong
as these warning statements are, they haven't prevented
occasional accidents in which glacial acetic acid is dispensed
from the pharmacy instead of a diluted form.
The word "glacial" (ice-like) refers to the fact
that, at its freezing point of 17 degrees Celsius, pure
acetic acid forms crystals and "freezes," looking
like a glacier. Diluted forms of acetic acid are used to
treat certain infections of the outer ear and the ear canal
(e.g., DOMEBORO OTIC is 2%), and to identify cervical
dysplasia during colposcopy (3-5% solution) after an abnormal
Pap smear. Vinegar is 5% acetic acid; this concentration
has also been used medically for irrigation. A 0.25% concentration
of acetic acid is commercially available as a premixed irrigation,
used primarily in bladders and wounds.
In one case of dispensing an undiluted form, a nurse called
the pharmacy for "acetic acid for irrigation" for a 31-year-old patient with paraplegia, osteomyelitis,
and bilateral greater trochanter wounds. An experienced
pharmacist, yet new to the institution, placed glacial acetic
acid at the window for pickup. This was used for 2 days
instead of an appropriate diluted form. The undiluted solution
resulted in burns to the extent that the wounds would not
heal, necessitating disarticulation at the hips.
In another hospital where the pharmacy routinely restocks
automated dispensing cabinets (ADCs) for patient care areas,
a recent refill request for the ambulatory surgery center
called for 30 mL of a 5% acetic acid solution. A pharmacy
technician obtained the bulk bottle of glacial acetic acid
and poured 30 mL directly into a 1 ounce bottle. The technician
was unaware that the product required dilution to make a
5% solution. The technician labeled the bottle as "acetic
acid - glacial." The pharmacist who checked the technician's
work was aware of the need for dilution but, despite the
label, he assumed that the technician had already performed
the required dilution. The bottle was then placed into stock
in the ambulatory surgery department's ADC and later removed
by nursing staff for administration to a patient. The nurses
and physician assumed the product had been diluted and did
not notice that "5%" was not listed on the label.
As a result, the physician used the glacial acetic acid
during a colposcopy. The patient experienced immediate vaginal
bleeding and blistering after the solution was applied,
and then severe pain when she awoke from sedation. The physician
did not immediately recognize the error, but he quickly
realized that something was wrong as soon as he applied
the acetic acid. The harm to the patient was temporary,
but she required a week off from work to recover.
In yet another case, a bottle of what should have been
3% acetic acid was sent to the operating room. However,
it was actually glacial acetic acid. One patient's skin
was bathed with the solution, causing first and second degree
Safe Practice Recommendation: Based on these and
other reports, it seems clear that a knowledge deficit exists
among some health professionals with respect to the properties
of glacial acetic acid. Some staff members may not recognize
that glacial refers to the most concentrated form of acetic
acid. E-mail this newsletter, or use it during staff meetings,
to assure that clinicians are aware of the differences between
various concentrations of this product. Although the warning
on the bottle seems clear, it may not be noticed. Keep in
mind, this product is packaged and labeled as a commercial
chemical. It is not a drug, and FDA approval is not required.
If this product must be maintained in inventory at all,
it would be helpful if more prominent alert messages were
placed on both the shelf and the bottle itself. One hospital
uses a neon-colored warning label that they designed themselves.
Another causative factor in the events described above
is the lack of an independent double check when dangerous
chemicals are handled. In one case, a pharmacist checked
the technician's work but only assumed that a dilution had
been made. There was no actual observation to reliably draw
that conclusion. No matter who prepares a dilution using
glacial acetic acid, recipes must be readily retrievable
to detail how the dilutions should be made and an independent
double check must be made of all materials, calculations,
and measurements, as well as labeling.
Some errors also appear to be related to the manner in
which the drug is prescribed, such as not including the
necessary strength or mentioning glacial acetic acid in
the order (e.g., "dilute glacial acetic acid" is one way it's been written.) In fact, in some cases, no
order is even written; acetic acid is just considered a
chemical that can be requested without an order. Obviously
an order should be required, and the exact strength necessary
must be included. Requests to dilute glacial acetic acid
should be made at least 1 day before it is needed to remove
the urgency of trying to honor unfamiliar requests.
One of our strongest recommendations during our hospital
consults has been to remove and discard unnecessary chemicals
from the compounding area within the pharmacy, particularly
those that have not been used within the last 6 months to
a year. This is often the case with glacial acetic acid.
In many cases, one of the aforementioned commercial preparations
can be used. In some cases, you may be able to use standard
table vinegar (5% acetic acid). If bulk chemicals must remain
in stock, store them in a locked, sequestered section of
the pharmacy. Another option is to dilute the product in
the concentrations needed immediately upon delivery of the
chemical. Thus, there would be no undiluted product in stock.