PRECAUTIONSGeneral
Abnormal Bleeding — SSRIs and SNRIs,
including fluoxetine, may increase the risk of bleeding events. Concomitant use
of aspirin, nonsteroidal anti-inflammatory drugs, warfarin, and other
anti-coagulants may add to this risk. Case reports and epidemiological studies
(case-control and cohort design) have demonstrated an association between use of
drugs that interfere with serotonin reuptake and the occurrence of
gastrointestinal bleeding. Bleeding events related to SSRIs and SNRIs use have
ranged from ecchymoses, hematomas, epistaxis, and petechiae to life-threatening
hemorrhages.
Patients should be cautioned about the risk of bleeding associated with the
concomitant use of fluoxetine and NSAIDs, aspirin, or other drugs that affect
coagulation (see Drug
Interactions).
Anxiety and Insomnia — In US
placebo–controlled clinical trials for major depressive disorder, 12% to 16% of
patients treated with Prozac and 7% to 9% of patients treated with placebo
reported anxiety, nervousness, or insomnia.
In US placebo–controlled clinical trials for OCD, insomnia was reported in
28% of patients treated with Prozac and in 22% of patients treated with placebo.
Anxiety was reported in 14% of patients treated with Prozac and in 7% of
patients treated with placebo.
In US placebo–controlled clinical trials for bulimia nervosa, insomnia was
reported in 33% of patients treated with Prozac 60 mg, and 13% of patients
treated with placebo. Anxiety and nervousness were reported, respectively, in
15% and 11% of patients treated with Prozac 60 mg and in 9% and 5% of patients
treated with placebo.
Among the most common adverse events associated with discontinuation
(incidence at least twice that for placebo and at least 1% for Prozac in
clinical trials collecting only a primary event associated with discontinuation)
in US placebo–controlled fluoxetine clinical trials were anxiety (2% in OCD),
insomnia (1% in combined indications and 2% in bulimia), and nervousness (1% in
major depressive disorder) (see
Table 4).
Altered Appetite and Weight — Significant
weight loss, especially in underweight depressed or bulimic patients may be an
undesirable result of treatment with Prozac.
In US placebo–controlled clinical trials for major depressive disorder, 11%
of patients treated with Prozac and 2% of patients treated with placebo reported
anorexia (decreased appetite). Weight loss was reported in 1.4% of patients
treated with Prozac and in 0.5% of patients treated with placebo. However, only
rarely have patients discontinued treatment with Prozac because of anorexia or
weight loss (see also
Pediatric Use under PRECAUTIONS).
In US placebo–controlled clinical trials for OCD, 17% of patients treated
with Prozac and 10% of patients treated with placebo reported anorexia
(decreased appetite). One patient discontinued treatment with Prozac because of
anorexia (see also Pediatric
Use under PRECAUTIONS).
In US placebo–controlled clinical trials for bulimia nervosa, 8% of patients
treated with Prozac 60 mg and 4% of patients treated with placebo reported
anorexia (decreased appetite). Patients treated with Prozac 60 mg on average
lost 0.45 kg compared with a gain of 0.16 kg by patients treated with placebo in
the 16–week double–blind trial. Weight change should be monitored during
therapy.
Activation of Mania/Hypomania — In US
placebo–controlled clinical trials for major depressive disorder,
mania/hypomania was reported in 0.1% of patients treated with Prozac and 0.1% of
patients treated with placebo. Activation of mania/hypomania has also been
reported in a small proportion of patients with Major Affective Disorder treated
with other marketed drugs effective in the treatment of major depressive
disorder (see also Pediatric
Use under PRECAUTIONS).
In US placebo–controlled clinical trials for OCD, mania/hypomania was
reported in 0.8% of patients treated with Prozac and no patients treated with
placebo. No patients reported mania/hypomania in US placebo–controlled clinical
trials for bulimia. In all US Prozac clinical trials as of May 8, 1995, 0.7% of
10,782 patients reported mania/hypomania (see also Pediatric Use under
PRECAUTIONS).
Hyponatremia — Hyponatremia may occur as
a result of treatment with SSRIs and SNRIs, including Prozac. In many cases,
this hyponatremia appears to be the result of the syndrome of inappropriate
antidiuretic hormone secretion (SIADH). Cases with serum sodium lower than 110
mmol/L have been reported and appeared to be reversible when Prozac was
discontinued. Elderly patients may be at greater risk of developing hyponatremia
with SSRIs and SNRIs. Also, patients taking diuretics or who are otherwise
volume depleted may be at greater risk (see Geriatric Use). Discontinuation of Prozac should be
considered in patients with symptomatic hyponatremia and appropriate medical
intervention should be instituted.
Signs and symptoms of hyponatremia include headache, difficulty
concentrating, memory impairment, confusion, weakness, and unsteadiness, which
may lead to falls. More severe and/or acute cases have been associated with
hallucination, syncope, seizure, coma, respiratory arrest, and death.
Seizures — In US placebo–controlled
clinical trials for major depressive disorder, convulsions (or events described
as possibly having been seizures) were reported in 0.1% of patients treated with
Prozac and 0.2% of patients treated with placebo. No patients reported
convulsions in US placebo–controlled clinical trials for either OCD or bulimia.
In all US Prozac clinical trials as of May 8, 1995, 0.2% of 10,782 patients
reported convulsions. The percentage appears to be similar to that associated
with other marketed drugs effective in the treatment of major depressive
disorder. Prozac should be introduced with care in patients with a history of
seizures.
The Long Elimination Half–Lives of Fluoxetine
and its Metabolites — Because of the long elimination half–lives of the
parent drug and its major active metabolite, changes in dose will not be fully
reflected in plasma for several weeks, affecting both strategies for titration
to final dose and withdrawal from treatment (see CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION).
Use in Patients with Concomitant Illness
— Clinical experience with Prozac in patients with concomitant systemic illness
is limited. Caution is advisable in using Prozac in patients with diseases or
conditions that could affect metabolism or hemodynamic responses.
Fluoxetine has not been evaluated or used to any appreciable extent in
patients with a recent history of myocardial infarction or unstable heart
disease. Patients with these diagnoses were systematically excluded from
clinical studies during the product’s premarket testing. However, the
electrocardiograms of 312 patients who received Prozac in double–blind trials
were retrospectively evaluated; no conduction abnormalities that resulted in
heart block were observed. The mean heart rate was reduced by approximately
3 beats/min.
In subjects with cirrhosis of the liver, the clearances of fluoxetine and its
active metabolite, norfluoxetine, were decreased, thus increasing the
elimination half–lives of these substances. A lower or less frequent dose should
be used in patients with cirrhosis.
Studies in depressed patients on dialysis did not reveal excessive
accumulation of fluoxetine or norfluoxetine in plasma (see Renal disease under CLINICAL PHARMACOLOGY). Use of a lower or less
frequent dose for renally impaired patients is not routinely necessary (see DOSAGE AND
ADMINISTRATION).
In patients with diabetes, Prozac may alter glycemic control. Hypoglycemia
has occurred during therapy with Prozac, and hyperglycemia has developed
following discontinuation of the drug. As is true with many other types of
medication when taken concurrently by patients with diabetes, insulin and/or
oral hypoglycemic dosage may need to be adjusted when therapy with Prozac is
instituted or discontinued.
Interference with Cognitive and Motor
Performance — Any psychoactive drug may impair judgment, thinking, or
motor skills, and patients should be cautioned about operating hazardous
machinery, including automobiles, until they are reasonably certain that the
drug treatment does not affect them adversely.
Discontinuation of Treatment with Prozac
— During marketing of Prozac and other SSRIs and SNRIs (serotonin and
norepinephrine reuptake inhibitors), there have been spontaneous reports of
adverse events occurring upon discontinuation of these drugs, particularly when
abrupt, including the following: dysphoric mood, irritability, agitation,
dizziness, sensory disturbances (e.g., paresthesias such as electric shock
sensations), anxiety, confusion, headache, lethargy, emotional lability,
insomnia, and hypomania. While these events are generally self–limiting, there
have been reports of serious discontinuation symptoms. Patients should be
monitored for these symptoms when discontinuing treatment with Prozac. A gradual
reduction in the dose rather than abrupt cessation is recommended whenever
possible. If intolerable symptoms occur following a decrease in the dose or upon
discontinuation of treatment, then resuming the previously prescribed dose may
be considered. Subsequently, the physician may continue decreasing the dose but
at a more gradual rate. Plasma fluoxetine and norfluoxetine concentration
decrease gradually at the conclusion of therapy, which may minimize the risk of
discontinuation symptoms with this drug (see DOSAGE AND ADMINISTRATION).
Information for Patients
Prescribers or other health professionals should inform patients,
their families, and their caregivers about the benefits and risks associated
with treatment with Prozac and should counsel them in its appropriate use. A
patient Medication Guide about“Antidepressant Medicines, Depression and other
Serious Mental Illnesses, and Suicidal Thoughts or Actions” is available for
Prozac. The prescriber or health professional should instruct patients, their
families, and their caregivers to read the Medication Guide and should assist
them in understanding its contents. Patients should be given the opportunity to
discuss the contents of the Medication Guide and to obtain answers to any
questions they may have. The complete text of the Medication Guide is reprinted
at the end of this document.
Patients should be advised of the following issues and asked to alert their
prescriber if these occur while taking Prozac.
Clinical Worsening and Suicide Risk —
Patients, their families, and their caregivers should be encouraged to be alert
to the emergence of anxiety, agitation, panic attacks, insomnia, irritability,
hostility, aggressiveness, impulsivity, akathisia (psychomotor restlessness),
hypomania, mania, other unusual changes in behavior, worsening of depression,
and suicidal ideation, especially early during antidepressant treatment and when
the dose is adjusted up or down. Families and caregivers of patients should be
advised to look for the emergence of such symptoms on a day–to–day basis, since
changes may be abrupt. Such symptoms should be reported to the patient’s
prescriber or health professional, especially if they are severe, abrupt in
onset, or were not part of the patient’s presenting symptoms. Symptoms such as
these may be associated with an increased risk for suicidal thinking and
behavior and indicate a need for very close monitoring and possibly changes in
the medication.
Serotonin Syndrome — Patients should be
cautioned about the risk of serotonin syndrome with the concomitant use of
Prozac and triptans, tramadol or other serotonergic agents.
Because Prozac may impair judgment, thinking, or motor skills,
patients should be advised to avoid driving a car or operating hazardous
machinery until they are reasonably certain that their performance is not
affected.
Patients should be advised to inform their physician if they are
taking or plan to take any prescription or over–the–counter drugs, or
alcohol.
Abnormal Bleeding- Patients should be
cautioned about the concomitant use of fluoxetine and NSAIDs, aspirin, warfarin,
or other drugs that affect coagulation since combined use of psychotropic drugs
that interfere with serotonin reuptake and these agents have been associated
with an increased risk of bleeding (see PRECAUTIONS, Abnormal Bleeding).
Patients should be advised to notify their physician if they
become pregnant or intend to become pregnant during therapy.
Patients should be advised to notify their physician if they are
breast–feeding an infant.
Patients should be advised to notify their physician if they
develop a rash or hives.
Laboratory Tests
There are no specific laboratory tests recommended.
Drug Interactions
As with all drugs, the potential for interaction by a variety of
mechanisms (e.g., pharmacodynamic, pharmacokinetic drug inhibition or
enhancement, etc.) is a possibility (see Accumulation and slow elimination under CLINICAL PHARMACOLOGY).
Drugs metabolized by CYP2D6 —
Fluoxetine inhibits the activity of CYP2D6, and may make individuals with normal
CYP2D6 metabolic activity resemble a poor metabolizer. Coadministration of
fluoxetine with other drugs that are metabolized by CYP2D6, including certain
antidepressants (e.g., TCAs), antipsychotics (e.g., phenothiazines and most
atypicals), and antiarrhythmics (e.g., propafenone, flecainide, and others)
should be approached with caution. Therapy with medications that are
predominantly metabolized by the CYP2D6 system and that have a relatively narrow
therapeutic index (see list below) should be initiated at the low end of the
dose range if a patient is receiving fluoxetine concurrently or has taken it in
the previous 5 weeks. Thus, his/her dosing requirements resemble those of poor
metabolizers. If fluoxetine is added to the treatment regimen of a patient
already receiving a drug metabolized by CYP2D6, the need for decreased dose of
the original medication should be considered. Drugs with a narrow therapeutic
index represent the greatest concern (e.g., flecainide, propafenone,
vinblastine, and TCAs). Due to the risk of serious ventricular arrhythmias and
sudden death potentially associated with elevated plasma levels of thioridazine,
thioridazine should not be administered with fluoxetine or within a minimum of
5 weeks after fluoxetine has been discontinued (see CONTRAINDICATIONS and WARNINGS).
Drugs metabolized by CYP3A4 — In an
in vivo interaction study involving coadministration of fluoxetine with single
doses of terfenadine (a CYP3A4 substrate), no increase in plasma terfenadine
concentrations occurred with concomitant fluoxetine. In addition, in vitro
studies have shown ketoconazole, a potent inhibitor of CYP3A4 activity, to be at
least 100 times more potent than fluoxetine or norfluoxetine as an inhibitor of
the metabolism of several substrates for this enzyme, including astemizole,
cisapride, and midazolam. These data indicate that fluoxetine’s extent of
inhibition of CYP3A4 activity is not likely to be of clinical
significance.
CNS active drugs — The risk of using
Prozac in combination with other CNS active drugs has not been systematically
evaluated. Nonetheless, caution is advised if the concomitant administration of
Prozac and such drugs is required. In evaluating individual cases, consideration
should be given to using lower initial doses of the concomitantly administered
drugs, using conservative titration schedules, and monitoring of clinical status
(see Accumulation and slow
elimination under CLINICAL PHARMACOLOGY).
Anticonvulsants — Patients on stable
doses of phenytoin and carbamazepine have developed elevated plasma
anticonvulsant concentrations and clinical anticonvulsant toxicity following
initiation of concomitant fluoxetine treatment.
Antipsychotics — Some clinical data
suggests a possible pharmacodynamic and/or pharmacokinetic interaction between
SSRIs and antipsychotics. Elevation of blood levels of haloperidol and clozapine
has been observed in patients receiving concomitant fluoxetine. Clinical studies
of pimozide with other antidepressants demonstrate an increase in drug
interaction or QTc prolongation. While a specific study
with pimozide and fluoxetine has not been conducted, the potential for drug
interactions or QTc prolongation warrants restricting the
concurrent use of pimozide and Prozac. Concomitant use of Prozac and pimozide is
contraindicated (see
CONTRAINDICATIONS). For thioridazine, see CONTRAINDICATIONS and WARNINGS.
Benzodiazepines — The half–life of
concurrently administered diazepam may be prolonged in some patients (see Accumulation and slow
elimination under CLINICAL PHARMACOLOGY).
Coadministration of alprazolam and fluoxetine has resulted in increased
alprazolam plasma concentrations and in further psychomotor performance
decrement due to increased alprazolam levels.
Lithium — There have been reports of
both increased and decreased lithium levels when lithium was used concomitantly
with fluoxetine. Cases of lithium toxicity and increased serotonergic effects
have been reported. Lithium levels should be monitored when these drugs are
administered concomitantly.
Tryptophan — Five patients receiving
Prozac in combination with tryptophan experienced adverse reactions, including
agitation, restlessness, and gastrointestinal distress.
Monoamine oxidase inhibitors — See CONTRAINDICATIONS.
Other drugs effective in the treatment of
major depressive disorder — In 2 studies, previously stable plasma levels
of imipramine and desipramine have increased greater than 2– to 10–fold when
fluoxetine has been administered in combination. This influence may persist for
3 weeks or longer after fluoxetine is discontinued. Thus, the dose of TCA may
need to be reduced and plasma TCA concentrations may need to be monitored
temporarily when fluoxetine is coadministered or has been recently discontinued
(see Accumulation and slow
elimination under CLINICAL PHARMACOLOGY, and Drugs metabolized by CYP2D6
under Drug Interactions).
Serotonergic drugs — Based on the
mechanism of action of SNRIs and SSRIs, including Prozac, and the potential for
serotonin syndrome, caution is advised when Prozac is coadministered with other
drugs that may affect the serotonergic neurotransmitter systems, such as
triptans, linezolid (an antibiotic which is a reversible non–selective MAOI),
lithium, tramadol, or St. John’s Wort (see Serotonin Syndrome under
WARNINGS). The concomitant use of Prozac with other SSRIs, SNRIs or tryptophan
is not recommended (see
Tryptophan).
Triptans — There have been rare
postmarketing reports of serotonin syndrome with use of an SSRI and a triptan.
If concomitant treatment of Prozac with a triptan is clinically warranted,
careful observation of the patient is advised, particularly during treatment
initiation and dose increases (see Serotonin Syndrome under
WARNINGS).
Potential effects of coadministration of
drugs tightly bound to plasma proteins — Because fluoxetine is tightly
bound to plasma protein, the administration of fluoxetine to a patient taking
another drug that is tightly bound to protein (e.g., Coumadin, digitoxin) may
cause a shift in plasma concentrations potentially resulting in an adverse
effect. Conversely, adverse effects may result from displacement of
protein–bound fluoxetine by other tightly–bound drugs (see Accumulation and slow
elimination under CLINICAL PHARMACOLOGY).
Drugs that interfere with hemostasis (e.g.,
NSAIDs, Aspirin, Warfarin) — Serotonin release by platelets plays an
important role in hemostasis. Epidemiological studies of the case–control and
cohort design that have demonstrated an association between use of psychotropic
drugs that interfere with serotonin reuptake and the occurrence of upper
gastrointestinal bleeding have also shown that concurrent use of an NSAID or
aspirin may potentiate this risk of bleeding. Altered anticoagulant effects,
including increased bleeding, have been reported when SSRIs or SNRIs are
coadministered with warfarin. Patients receiving warfarin therapy should be
carefully monitored when fluoxetine is initiated or discontinued.
Electroconvulsive therapy (ECT) —
There are no clinical studies establishing the benefit of the combined use of
ECT and fluoxetine. There have been rare reports of prolonged seizures in
patients on fluoxetine receiving ECT treatment.
Carcinogenesis, Mutagenesis, Impairment of
Fertility
There is no evidence of carcinogenicity or mutagenicity from
in vitro or animal studies. Impairment of fertility in adult animals at doses up
to 12.5 mg/kg/day (approximately 1.5 times the MRHD on a mg/m2 basis) was not observed.
Carcinogenicity — The dietary
administration of fluoxetine to rats and mice for 2 years at doses of up to 10
and 12 mg/kg/day, respectively [approximately 1.2 and 0.7 times, respectively,
the maximum recommended human dose (MRHD) of 80 mg on a mg/m2 basis], produced no evidence of carcinogenicity.
Mutagenicity — Fluoxetine and
norfluoxetine have been shown to have no genotoxic effects based on the
following assays: bacterial mutation assay, DNA repair assay in cultured rat
hepatocytes, mouse lymphoma assay, and in vivo sister chromatid exchange assay
in Chinese hamster bone marrow cells.
Impairment of fertility — Two
fertility studies conducted in adult rats at doses of up to 7.5 and
12.5 mg/kg/day (approximately 0.9 and 1.5 times the MRHD on a mg/m2 basis) indicated that fluoxetine had no adverse effects on
fertility (see Pediatric
Use).
PregnancyPregnancy Category C
In embryo–fetal development studies in rats and rabbits, there
was no evidence of teratogenicity following administration of up to 12.5 and
15 mg/kg/day, respectively (1.5 and 3.6 times, respectively, the MRHD of 80 mg
on a mg/m2 basis) throughout organogenesis. However, in
rat reproduction studies, an increase in stillborn pups, a decrease in pup
weight, and an increase in pup deaths during the first 7 days postpartum
occurred following maternal exposure to 12 mg/kg/day (1.5 times the MRHD on a
mg/m2 basis) during gestation or 7.5 mg/kg/day (0.9 times
the MRHD on a mg/m2 basis) during gestation and
lactation. There was no evidence of developmental neurotoxicity in the surviving
offspring of rats treated with 12 mg/kg/day during gestation. The no–effect dose
for rat pup mortality was 5 mg/kg/day (0.6 times the MRHD on a mg/m2 basis). Prozac should be used during pregnancy only if the
potential benefit justifies the potential risk to the fetus.
Nonteratogenic Effects
Neonates exposed to Prozac and other SSRIs or serotonin and
norepinephrine reuptake inhibitors (SNRIs), late in the third trimester have
developed complications requiring prolonged hospitalization, respiratory
support, and tube feeding. Such complications can arise immediately upon
delivery. Reported clinical findings have included respiratory distress,
cyanosis, apnea, seizures, temperature instability, feeding difficulty,
vomiting, hypoglycemia, hypotonia, hypertonia, hyperreflexia, tremor,
jitteriness, irritability, and constant crying. These features are consistent
with either a direct toxic effect of SSRIs and SNRIs or, possibly, a drug
discontinuation syndrome. It should be noted that, in some cases, the clinical
picture is consistent with serotonin syndrome (see Monoamine oxidase inhibitors under CONTRAINDICATIONS).
Infants exposed to SSRIs in late pregnancy may have an increased risk for
persistent pulmonary hypertension of the newborn (PPHN). PPHN occurs in 1–2 per
1000 live births in the general population and is associated with substantial
neonatal morbidity and mortality. In a retrospective case–control study of 377
women whose infants were born with PPHN and 836 women whose infants were born
healthy, the risk for developing PPHN was approximately six–fold higher for
infants exposed to SSRIs after the 20th week of gestation compared to infants
who had not been exposed to antidepressants during pregnancy. There is currently
no corroborative evidence regarding the risk for PPHN following exposure to
SSRIs in pregnancy; this is the first study that has investigated the potential
risk. The study did not include enough cases with exposure to individual SSRIs
to determine if all SSRIs posed similar levels of PPHN risk.
When treating a pregnant woman with Prozac during the third trimester, the
physician should carefully consider both the potential risks and benefits of
treatment (see DOSAGE AND
ADMINISTRATION). Physicians should note that in a prospective longitudinal
study of 201 women with a history of major depression who were euthymic at the
beginning of pregnancy, women who discontinued antidepressant medication during
pregnancy were more likely to experience a relapse of major depression than
women who continued antidepressant medication.
Labor and Delivery
The effect of Prozac on labor and delivery in humans is unknown.
However, because fluoxetine crosses the placenta and because of the possibility
that fluoxetine may have adverse effects on the newborn, fluoxetine should be
used during labor and delivery only if the potential benefit justifies the
potential risk to the fetus.
Nursing Mothers
Because Prozac is excreted in human milk, nursing while on Prozac
is not recommended. In one breast–milk sample, the concentration of fluoxetine
plus norfluoxetine was 70.4 ng/mL. The concentration in the mother’s plasma was
295.0 ng/mL. No adverse effects on the infant were reported. In another case, an
infant nursed by a mother on Prozac developed crying, sleep disturbance,
vomiting, and watery stools. The infant’s plasma drug levels were 340 ng/mL of
fluoxetine and 208 ng/mL of norfluoxetine on the second day of feeding.
Pediatric Use
The efficacy of Prozac for the treatment of major depressive
disorder was demonstrated in two 8– to 9–week placebo–controlled clinical trials
with 315 pediatric outpatients ages 8 to ≤18 (see CLINICAL TRIALS).