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© 2018 Journal of Family Medicine and Primary Care | Published by Wolters Kluwer - Medknow 1090
Introduction
Olanzapine is one of the most commonly used antipsychotic
agents. It is closely related to Clozapine chemically. The
dose‑related inducement of seizure by Clozapine though is well
known, and that of Olanzapine is limited. Among the trials
conducted for FDA approval of drugs, the incidence of seizure
was signicantly higher in the Clozapine and Olanzapine groups.[1]
The premarketing trials have found incidence of seizures at 0.88%,
which is comparable to other conventional antipsychotics.[1]
Despite its proconvulsant liability, the literature reporting seizures
are sparse. Few case reports of fatal status epilepticus and
myoclonic status have attributed Olanzapine as the causative
agent.[2,3] Hereby we are reporting a case of seizure in a patient
receiving Olanzapine with a brief review on seizure risk
associated with Olanzapine use.
Case Report
A 23‑year‑old female diagnosed with mild mental retardation
with schizophrenia with obsessive compulsive disorder under
treatment from a psychiatrist. On treatment review it was noted
that she had taken Olanzapine 20 mg with Fluoxetine 20 mg
for nearly 4 years with good response. She discontinued her
medicines nding a good improved period to relapse within
a year of stopping. On re‑emergence of symptoms she by
herself on parents’ advice restarted Olanzapine 20 mg with
Fluoxetine and within 3 months had an episode of seizures.
She then visited a psychiatrist who shifted her from Fluoxetine
to Escitalopram 10 mg. After 2 months of Olanzapine 20 mg
with Escitalopram 10 mg she had a second episode of seizure
with which she was brought to the hospital. Both the seizures
were of similar manifestation, starting with a prodrome
of dysphoric feeling and crying due to “unexplainable
discomfort” lasting for around 90 minutes late in the evening
and thereafter getting into sleep. Within an hour of sleep there
was sudden awakening with right‑sided twisting of head and
jerky movements followed by loosening of awareness and
then gradually spreading of jerky movements to whole of the
body. Confusion prevailed for few minutes before gaining full
consciousness.
On examination, tongue bite mark was noted without any focal
neurological decits. She had negative symptoms but no active
positive psychotic symptoms, depressive or obsessive compulsive
symptoms. Electroencephalogram (EEG) done after 12 hours of
Seizureassociatedwitholanzapine
N. A. Uvais1, V. S. Sreeraj2
1Department of Psychiatry, Iqraa International Hospital and Research Centre, Calicut, Kerala, 2Department of Psychiatry,
National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
Abs tr Act
Atypical antipsychotics are known to be associated with electroencephalogram abnormalities. Olanzapine can lower seizure threshold
and induce epileptiform discharges. However in patients on Olanzapine for the treatment of a primary psychiatric disorder, clinical
seizure is a rare occurrence. We report the case of a 23-year-old female with mild mental retardation with schizophrenia with obsessive
compulsive disorder who developed new-onset generalized tonic-clonic seizure probably due to Olanzapine. Electroencephalogram
showed epileptiform discharges. The seizure risk associated with Olanzapine was reviewed.
Keywords: Adverse effects, drug-induced seizure, Olanzapine, seizure
Case Report
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DOI:
10.4103/jfmpc.jfmpc_405_16
Address for correspondence: Dr. N. A. Uvais,
Department of Psychiatry, Iqraa International Hospital and
Research Centre, Calicut, Kerala, India.
E-mail: druvaisna@gmail.com
How to cite this article: Uvais NA, Sreeraj VS. Seizure associated with
olanzapine. J Family Med Prim Care 2018;7:1090-2.
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Uvais and Sreeraj: Olanzapine‑induced seizure
Journal of Family Medicine and Primary Care 1091 Volume 7 : Issue 5 : September-October 2018
seizure revealed intermittent generalized frontal‑dominant slow
wave activities suggestive of postictal state. Magnetic resonance
imaging brain showed diffuse atrophic changes.
Olanzapine was cross tapered with Risperidone. Carbamazepine
was started with Lorazepam as anticonvulsant. Escitalopram
was continued. Patient was discharged after 10 days with no
subsequent seizures.
Discussion
The case suggests precipitation of seizures by Olanzapine which
was restarted rapidly at the previously prescribed dose. Seizure
occurred after the patient was on Olanzapine and did not have
seizure in the brief follow‑up period of stopping it. No other
alternative explanation could be found for sudden appearance
of seizures in our case although a high‑risk state with mental
retardation was present. The adverse event got repeated in our
case but the trial for attribution by stopping and restarting the
medicines could not be done owing to high fatal risk of the
seizure. The objective evidence in the means of abnormal EEG
was noted. Thus concluding according to Naranjo algorithm with
a score of 5, the seizure occurring in our case was probably due
to Olanzapine.[4]
Olanzapine, seizure, and neurotransmitters
Among second‑generation antipsychotics, although Clozapine
is a well‑known agent inducing seizures, no drug is out of
risk. Various mechanisms have been considered to cause
seizures in persons on antipsychotics, reduction of GABA
neurotransmission being a common nal pathway. Dopamine D2
receptor antagonism, histaminergic H1 antagonism, and alpha‑1
antagonism have been commonly attributed.[5] Chronic alpha‑2
receptor and sigma‑1 receptor changes have also been noted.
As none of these mono‑neurotransmitters can explain the
differential seizurogenic potential of psychotropic drugs, dual
neurotransmitter/receptor imbalances have been hypothesized.
Drugs with higher dopamine:acetylcholine imbalance,
serotonin:acetylchloine imbalance, D1:D2 antagonism, alpha
1:alpha 2 antagonism, and alpha 1:D2 receptor affinities
are observed with higher rate of convulsions. Drugs with
more afnity on dopamine receptors in cortical compared to
subcortical (hippocampal/nigrostriatal) areas have also been
noted to increase seizure liability.[5]
Neurosteroids have also been commonly implicated.
Progesterone, allopregnanolone, and dehydroepiandrostenedione
protect against seizures by modulating GABA‑A, NMDA, and
acetylcholine receptors. Their secretion and metabolism are
often altered by Olanzapine and triggers kindling. Testosterone,
adrenocorticotropic hormone, and desoxycorticosterone also
may get affected, thereby increasing the risk of seizures. Estradiol,
cortisol, and thyroid hormones are by themselves proconvulsants
and on elevation during treatment with antipsychotics may
precipitate seizures.[5]
Although Olanzapine and Clozapine are structurally similar,
they differ in few of the receptor afnities. Olanzapine is
having higher D1, D2 and lower D4 dopamine receptor afnity
compared to Clozapine. It has only half the afnity to alpha‑1
in comparison to D2 receptor, whereas Clozapine has 18 times
higher afnity. More 5HT6 serotonergic action and lesser
muscarinic anticholinergic action with increasing neurosteroids
are observed in Olanzapine. All these have been hypothesized to
be the cause of lower risk of Olanzapine in decreasing seizure
threshold.[5] Hence we hypothesize that those with mutations
in genes encoding these receptors or their messenger systems
may have an elevated risk for seizure with Olanzapine.
Olanzapine and risk for seizures
Olanzapine is known to cause highest EEG changes, in 35‑45%
of cases,[6‑9] among the non‑Clozapine newer antipsychotics.[6‑9]
Atypicals have high propensity to cause EEG changes compared
to typical antipsychotics.[10] Generalized/focal symmetrical
theta and delta waves are more commonly found abnormal
activities followed by asymmetrical slow waves, sharp waves
with phase reversals, and spike‑and‑slow wave patterns. The
later severe epileptic changes were noted in up to 11‑15% of
cases on Olanzapine.[4,8,9] EEG changes were noted at around
4‑7 months of starting Olanzapine in most of the literature.[1,2,8]
As abnormal EEG could be seen in most of the reported cases
including our case, it would be seen benecial to monitor EEG
as a seizure preventive strategy in high‑risk patients after the
cost effectiveness being evaluated. Few of the high‑risk groups
as discussed below would benet from it.
No prospective data regarding mean duration of appearance of
changes have been done. But dose and duration both were not
found to be correlating with the EEG changes. As in our case,
the patient had long‑term Olanzapine use, but had discontinued
and restarted which led to seizures. Abrupt changes in doses
are noted to increase the risk.[11] An acute stimulation of
Olanzapine‑sensitized/kindled neurons could be elevating the risk.
A U‑shaped relation of dose–seizure frequency was established
for conventional antipsychotics like Chlorpromazine.[12] Similar
mechanism of seizurogenic potential at a dose lower than
therapeutic level might be inducing seizures with Olanzapine. The
presensitized patients having developed tolerance would be at a
lower therapeutic range in synapses even at the prior doses. Thus,
the prior dose could be precipitating a seizure as a co‑occurrence
which is lower than the therapeutic level.
Old age, organicity, epilepsy, hypertension, bipolar disorders,
and comorbid OCD are few known factors associated with
Olanzapine‑induced seizures.[13] Multiple psychotropic drugs
except Benzodiazepines[7,13‑15] change from typical to atypical
antipsychotic,[11,16] and addition of another serotonin–dopamine
inhibitor (Quetiapine) to Olanzapine is seen in reported cases
of Olanzapine‑induced seizures.[15] As in our case, the presence
of mental retardation, obsessive compulsive disorder, and SSRI
would have increased the risk of seizure with Olanzapine.
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Uvais and Sreeraj: Olanzapine‑induced seizure
Journal of Family Medicine and Primary Care 1092 Volume 7 : Issue 5 : September-October 2018
No expert reviews exist regarding the suitable way of
managing these seizures. Stopping Olanzapine though could be
recommended, the risk of cholinergic rebound effects on abrupt
cessation of Olanzapine should be monitored. Olanzapine might
take few weeks to completely wane off from the body even
after stopping. With the report of fatal status epilepticus and
persistence of abnormal EEG, the need of anticonvulsants at
least until normalization of EEG could be considered.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conicts of interest.
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