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FDA Public Health Advisory
Seizures in Patients Without Epilepsy Being Treated
With Gabitril (tiagabine)
February 18, 2005
Today the Food and Drug Administration announced
that a Bolded Warning will be added to the labeling for Gabitril (tiagabine)
to warn prescribers of the risk of seizures in patients without
epilepsy being treated with this drug. Gabitril has been approved
since 1997 for patients 12 years of age and older as adjunctive
therapy (used in addition to other medications) for partial
seizures. Recently, the Agency has become aware of reports of the
occurrence of seizures in more than 30 patients prescribed Gabitril
for conditions other than epilepsy. Most of these uses were in
patients with psychiatric illnesses. Such so-called off label
prescribing is a common practice among physicians. Because of the
risk of seizures, however, in addition to adding the Bolded Warning
to product labeling, the sponsor has agreed to undertake an
educational campaign targeted to healthcare professionals and
patients in which such off label use will be discouraged.
In addition to the occurrence of isolated seizures, the Agency has
received several reports of status epilepticus in patients without
epilepsy. Status epilepticus is a particularly dangerous event, in
which patients have continuous seizures without regaining
consciousness between seizures. In some cases, prescribers have
continued to treat with, or actually increased the dose of, Gabitril
in patients without epilepsy in whom seizures occurred. Presumably,
this was done because the prescribers were unaware of the
possibility that Gabitril could cause seizures and they believed
that, as a drug approved to treat epilepsy, Gabitril might be
beneficial in this situation as well.
Typically, the seizures have occurred soon after the initiation of
treatment with Gabitril, or soon after an increase in dose, although
some patients experienced seizures after several months of
treatment. Some seizures have occurred at very low doses compared to
the doses approved for use in patients with epilepsy. Although most
of the patients in whom seizures occurred were also taking other
medications that may infrequently cause seizures, the temporal
relationship to the initiation of treatment with Gabitril or to dose
increases in many cases, as well as the number of patients reporting
seizures, strongly suggests that the seizures were caused by
Gabitril.
Because the system for reporting adverse events is voluntary, the
number of reports of adverse reactions that the Agency receives once
a drug has been marketed is probably less than the actual number of
reactions that have actually occurred. For this reason, it is
expected that the number of patients who have experienced a seizure
while taking Gabitril is likely to be greater than the number
reported, although it is impossible to know what the difference
might be.
Because seizures are a serious and potentially life-threatening
event and because prescribers are unlikely to expect that a drug to
treat epilepsy can cause seizures in other patients, the Agency has
requested that this information be included in a Bolded Warning and
announced to healthcare professionals with a Dear Health Care
Practitioner letter from the sponsor. In addition, as noted
above, the sponsor has agreed to undertake an educational campaign
in which they will discourage the off label use of Gabitril.
The Agency will work closely with the sponsor to expedite the
adoption and dissemination of the revised label and educational
materials.
Healthcare professionals should be aware that the use of Gabitril
for any indication other than for partial seizures in patients with
epilepsy who are at least 12 years old is an off label use,
meaning evidence to support the safety and effectiveness for those
uses has not been approved by the FDA. For this reason, the labeling
for Gabitril will not contain any needed precautions and warnings
that might result from such a submission and review. Patients should
be aware that the use of Gabitril for the treatment of any condition
other than partial seizures is considered off label use, and
that there is a risk that they may experience a seizure. The risks
of seizures should be explained, and patients should report any
adverse events promptly to their healthcare professional.
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Date created: February 18, 2005 |
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