General
Abnormal Bleeding – Published case
reports have documented the occurrence of bleeding episodes in patients treated
with psychotropic drugs that interfere with serotonin reuptake. Subsequent
epidemiological studies, both of the case-control and cohort design, have
demonstrated an association between use of psychotropic drugs that interfere
with serotonin reuptake and the occurrence of upper gastrointestinal bleeding.
In two studies, concurrent use of a nonsteroidal anti-inflammatory drug (NSAID)
or aspirin potentiated the risk of bleeding (see Drug Interactions). Although
these studies focused on upper gastrointestinal bleeding, there is reason to
believe that bleeding at other sites may be similarly potentiated. Patients
should be cautioned regarding the risk of bleeding associated with the
concomitant use of fluoxetine with NSAIDs, aspirin, or other drugs that affect
coagulation.
Anxiety and Insomnia – In U.S.
placebo-controlled clinical trials for major depressive disorder, 12% to 16% of
patients treated with fluoxetine and 7% to 9% of patients treated with placebo
reported anxiety, nervousness, or insomnia.
In U.S. placebo-controlled clinical trials for OCD, insomnia was reported in
28% of patients treated with fluoxetine and in 22% of patients treated with
placebo. Anxiety was reported in 14% of patients treated with fluoxetine and in
7% of patients treated with placebo.
In U.S. placebo-controlled clinical trials for bulimia nervosa, insomnia was
reported in 33% of patients treated with fluoxetine 60 mg, and 13% of patients
treated with placebo. Anxiety and nervousness were reported, respectively, in
15% and 11% of patients treated with fluoxetine 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 fluoxetine in
clinical trials collecting only a primary event associated with discontinuation)
in U.S. 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 fluoxetine.
In U.S. placebo-controlled clinical trials for major depressive disorder, 11%
of patients treated with fluoxetine and 2% of patients treated with placebo
reported anorexia (decreased appetite). Weight loss was reported in 1.4% of
patients treated with fluoxetine and in 0.5% of patients treated with placebo.
However, only rarely have patients discontinued treatment with fluoxetine
because of anorexia or weight loss (see also Pediatric Use under
PRECAUTIONS).
In U.S. placebo-controlled clinical trials for OCD, 17% of patients treated
with fluoxetine and 10% of patients treated with placebo reported anorexia
(decreased appetite). One patient discontinued treatment with fluoxetine because
of anorexia (see also Pediatric Use under PRECAUTIONS).
In U.S. placebo-controlled clinical trials for bulimia nervosa, 8% of
patients treated with fluoxetine 60 mg and 4% of patients treated with placebo
reported anorexia (decreased appetite). Patients treated with fluoxetine 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 U.S.
placebo-controlled clinical trials for major depressive disorder,
mania/hypomania was reported in 0.1% of patients treated with fluoxetine 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 U.S. placebo-controlled clinical trials for OCD, mania/hypomania was
reported in 0.8% of patients treated with fluoxetine and no patients treated
with placebo. No patients reported mania/hypomania in U.S. placebo-controlled
clinical trials for bulimia. In all U.S. fluoxetine clinical trials as of May 8,
1995, 0.7% of 10,782 patients reported mania/hypomania (see
also Pediatric Use under
PRECAUTIONS).
Hyponatremia – Cases of hyponatremia
(some with serum sodium lower than 110 mmol/L) have been reported. The
hyponatremia appeared to be reversible when fluoxetine was discontinued.
Although these cases were complex with varying possible etiologies, some were
possibly due to the syndrome of inappropriate antidiuretic hormone secretion
(SIADH). The majority of these occurrences have been in older patients and in
patients taking diuretics or who were otherwise volume depleted. In two 6-week
controlled studies in patients greater than or equal to 60 years of age, 10 of 323 fluoxetine patients
and 6 of 327 placebo recipients had a lowering of serum sodium below the
reference range; this difference was not statistically significant. The lowest
observed concentration was 129 mmol/L. The observed decreases were not
clinically significant.
Seizures – In U.S. 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
fluoxetine and 0.2% of patients treated with placebo. No patients reported
convulsions in U.S. placebo-controlled clinical trials for either OCD or
bulimia. In all U.S. fluoxetine 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. Fluoxetine 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 fluoxetine in patients with concomitant systemic
illness is limited. Caution is advisable in using fluoxetine 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 fluoxetine 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, fluoxetine may alter glycemic control.
Hypoglycemia has occurred during therapy with fluoxetine, 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
fluoxetine 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
Fluoxetine – During marketing of fluoxetine 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 fluoxetine. 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 fluoxetine and should counsel them in its appropriate use. A
patient Medication Guide about “Antidepressant Medicines, Depression and other
Serious Mental Illness, and Suicidal Thoughts or Actions” is available for
fluoxetine. 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 fluoxetine.
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
fluoxetine and triptans, tramadol or other serotonergic agents.
Because fluoxetine 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.
Patients should be cautioned about the concomitant use of fluoxetine and
NSAIDs, aspirin, 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.
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
fluoxetine in combination with other CNS active drugs has not been
systematically evaluated. Nonetheless, caution is advised if the concomitant
administration of fluoxetine 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 fluoxetine. Concomitant use of fluoxetine 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
fluoxetine 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 PRECAUTIONS, Drug Interactions).
Serotonergic Drugs – Based on the
mechanism of action of SNRIs and SSRIs, including fluoxetine and the potential
for serotonin syndrome, caution is advised when fluoxetine 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 fluoxetine 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 fluoxetine 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
(NSAIDs, Aspirin, Warfarin, etc.) – 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 potentiated the risk of bleeding. Thus, patients should be cautioned
about the use of such drugs concurrently with fluoxetine.
Warfarin – Altered anticoagulant
effects, including increased bleeding, have been reported when fluoxetine is
coadministered with warfarin. Patients receiving warfarin therapy should receive
careful coagulation monitoring when fluoxetine is initiated or stopped.
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).
Pregnancy
Pregnancy 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).
Fluoxetine should be used during pregnancy only if the potential benefit
justifies the potential risk to the fetus.
Nonteratogenic Effects – Neonates
exposed to fluoxetine 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 to 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 fluoxetine 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 fluoxetine 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 fluoxetine is excreted in human milk, nursing while on
fluoxetine 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 fluoxetine 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 fluoxetine 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).
The efficacy of fluoxetine for the treatment of OCD was demonstrated in one
13-week placebo-controlled clinical trial with 103 pediatric outpatients ages 7
to less than 18 (see
CLINICAL TRIALS).
The safety and effectiveness in pediatric patients less than 8 years of age in
major depressive disorder and less than 7 years of age in OCD have not been
established.
Fluoxetine pharmacokinetics were evaluated in 21 pediatric patients (ages 6
to less than or equal to 18) with major depressive disorder or OCD (see
Pharmacokinetics under CLINICAL PHARMACOLOGY). The acute adverse event
profiles observed in the 3 studies (N=418 randomized; 228 fluoxetine-treated,
190 placebo-treated) were generally similar to that observed in adult studies
with fluoxetine. The longer-term adverse event profile observed in the 19-week
major depressive disorder study (N=219 randomized; 109 fluoxetine-treated, 110
placebo-treated) was also similar to that observed in adult trials with
fluoxetine (see ADVERSE REACTIONS).
Manic reaction, including mania and hypomania, was reported in 6 (1 mania, 5
hypomania) out of 228 (2.6%) fluoxetine-treated patients and in 0 out of 190
(0%) placebo-treated patients. Mania/hypomania led to the discontinuation of 4
(1.8%) fluoxetine-treated patients from the acute phases of the 3 studies
combined. Consequently, regular monitoring for the occurrence of mania/hypomania
is recommended.
As with other SSRIs, decreased weight gain has been observed in association
with the use of fluoxetine in children and adolescent patients. After 19 weeks
of treatment in a clinical trial, pediatric subjects treated with fluoxetine
gained an average of 1.1 cm less in height (p=0.004) and 1.1 kg less in weight
(p=0.008) than subjects treated with placebo. In addition, fluoxetine treatment
was associated with a decrease in alkaline phosphatase levels. The safety of
fluoxetine treatment for pediatric patients has not been systematically assessed
for chronic treatment longer than several months in duration. In particular,
there are no studies that directly evaluate the longer-term effects of
fluoxetine on the growth, development, and maturation of children and adolescent
patients. Therefore, height and weight should be monitored periodically in
pediatric patients receiving fluoxetine.
(See
WARNINGS, Clinical
Worsening and Suicide Risk.)
Significant toxicity, including myotoxicity, long-term neurobehavioral and
reproductive toxicity, and impaired bone development, has been observed
following exposure of juvenile animals to fluoxetine. Some of these effects
occurred at clinically relevant exposures.
In a study in which fluoxetine (3, 10, or 30 mg/kg) was orally administered
to young rats from weaning (Postnatal Day 21) through adulthood (Day 90), male
and female sexual development was delayed at all doses, and growth (body weight
gain, femur length) was decreased during the dosing period in animals receiving
the highest dose. At the end of the treatment period, serum levels of creatine
kinase (marker of muscle damage) were increased at the intermediate and high
doses, and abnormal muscle and reproductive organ histopathology (skeletal
muscle degeneration and necrosis, testicular degeneration and necrosis,
epididymal vacuolation and hypospermia) was observed at the high dose. When
animals were evaluated after a recovery period (up to 11 weeks after cessation
of dosing), neurobehavioral abnormalities (decreased reactivity at all doses and
learning deficit at the high dose) and reproductive functional impairment
(decreased mating at all doses and impaired fertility at the high dose) were
seen; in addition, testicular and epididymal microscopic lesions and decreased
sperm concentrations were found in the high dose group, indicating that the
reproductive organ effects seen at the end of treatment were irreversible. The
reversibility of fluoxetine-induced muscle damage was not assessed. Adverse
effects similar to those observed in rats treated with fluoxetine during the
juvenile period have not been reported after administration of fluoxetine to
adult animals. Plasma exposures (AUC) to fluoxetine in juvenile rats receiving
the low, intermediate, and high dose in this study were approximately 0.1 to
0.2, 1 to 2, and 5 to 10 times, respectively, the average exposure in pediatric
patients receiving the maximum recommended dose (MRD) of 20 mg/day. Rat
exposures to the major metabolite, norfluoxetine, were approximately 0.3 to 0.8,
1 to 8, and 3 to 20 times, respectively, pediatric exposure at the MRD.
A specific effect of fluoxetine on bone development has been reported in mice
treated with fluoxetine during the juvenile period. When mice were treated with
fluoxetine (5 or 20 mg/kg, intraperitoneal) for 4 weeks starting at 4 weeks of
age, bone formation was reduced resulting in decreased bone mineral content and
density. These doses did not affect overall growth (body weight gain or femoral
length). The doses administered to juvenile mice in this study are approximately
0.5 and 2 times the MRD for pediatric patients on a body surface area (mg/m2) basis.
In another mouse study, administration of fluoxetine (10 mg/kg
intraperitoneal) during early postnatal development (Postnatal Days 4 to 21)
produced abnormal emotional behaviors (decreased exploratory behavior in
elevated plus-maze, increased shock avoidance latency) in adulthood (12 weeks of
age). The dose used in this study is approximately equal to the pediatric MRD on
a mg/m2 basis. Because of the early dosing period in this
study, the significance of these findings to the approved pediatric use in
humans is uncertain.
Fluoxetine is approved for use in pediatric patients with MDD and OCD (see BOX WARNING and
WARNINGS, Clinical
Worsening and Suicide Risk). Anyone considering the use of fluoxetine
in a child or adolescent must balance the potential risks with the clinical
need.
Geriatric Use
U.S. fluoxetine clinical trials as of May 8, 1995 (10,782
patients) included 687 patients ≥65 years of age and 93 patients ≥75 years of
age. The efficacy in geriatric patients has been established (see CLINICAL
TRIALS). For pharmacokinetic information in geriatric patients, see
Age under CLINICAL
PHARMACOLOGY. No overall differences in safety or effectiveness were
observed between these subjects and younger subjects, and other reported
clinical experience has not identified differences in responses between the
elderly and younger patients, but greater sensitivity of some older individuals
cannot be ruled out. As with other SSRIs, fluoxetine has been associated with
cases of clinically significant hyponatremia in elderly patients (see
Hyponatremia under PRECAUTIONS).