Discontinuation of Treatment with Citalopram Tablets
During marketing of citalopram 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 citalopram. 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 (see
DOSAGE AND ADMINISTRATION).
Abnormal Bleeding
SSRIs and SNRIs, including citalopram, may increase the risk of bleeding events. Concomitant use of aspirin, nonsteroidal anti-inflammatory drugs, warfarin, and other anticoagulants may add to the 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 citalopram and NSAIDs, aspirin, or other drugs that affect coagulation.
Hyponatremia
Hyponatremia may occur as a result of treatment with SSRIs and SNRIs, including citalopram. In many cases, this hyponatremia appears to be the result of the syndrome of inappropriate antidiuretic hormone secretion (SIADH), and was reversible when citalopram was discontinued. Cases with serum sodium lower than 110 mmol/L have been reported. 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 citalopram 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. Signs and symptoms associated with more severe and/or acute cases have included hallucination, syncope, seizure, coma, respiratory arrest, and death.
Activation of Mania/Hypomania
In placebo-controlled trials of citalopram tablets, some of which included patients with bipolar disorder, activation of mania/hypomania was reported in 0.2% of 1063 patients treated with citalopram tablets and in none of the 446 patients treated with placebo. Activation of mania/hypomania has also been reported in a small proportion of patients with major affective disorders treated with other marketed antidepressants. As with all antidepressants, citalopram tablets should be used cautiously in patients with a history of mania.
Seizures
Although anticonvulsant effects of citalopram have been observed in animal studies, citalopram tablets have not been systematically evaluated in patients with a seizure disorder. These patients were excluded from clinical studies during the product's premarketing testing. In clinical trials of citalopram tablets, seizures occurred in 0.3% of patients treated with citalopram tablets (a rate of one patient per 98 years of exposure) and 0.5% of patients treated with placebo (a rate of one patient per 50 years of exposure). Like other antidepressants, citalopram tablets should be introduced with care in patients with a history of seizure disorder.
Interference with Cognitive and Motor Performance
In studies in normal volunteers, citalopram tablets in doses of 40 mg/day did not produce impairment of intellectual function or psychomotor performance. Because any psychoactive drug may impair judgment, thinking, or motor skills, however, patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that citalopram tablets therapy does not affect their ability to engage in such activities.
Use in Patients with Concomitant Illness
Clinical experience with citalopram tablets are in patients with certain concomitant systemic illnesses is limited. Caution is advisable in using citalopram tablets in patients with diseases or conditions that produce altered metabolism or hemodynamic responses.
Citalopram tablets have not been systematically evaluated in patients with a recent history of myocardial infarction or unstable heart disease. Patients with these diagnoses were generally excluded from clinical studies during the product's premarketing testing. However, the electrocardiograms of 1116 patients who received citalopram tablets in clinical trials were evaluated and the data indicate that citalopram tablets are not associated with the development of clinically significant ECG abnormalities.
In subjects with hepatic impairment, citalopram clearance was decreased and plasma concentrations were increased. The use of citalopram tablets in hepatically impaired patients should be approached with caution and a lower maximum dosage is recommended (see
DOSAGE AND ADMINISTRATION).
Because citalopram is extensively metabolized, excretion of unchanged drug in urine is a minor route of elimination. Until adequate numbers of patients with severe renal impairment have been evaluated during chronic treatment with citalopram tablets, however, they should be used with caution in such patients (see
DOSAGE AND ADMINISTRATION).
Information for Patients
Physicians are advised to discuss the following issues with patients for whom they prescribe citalopram tablets.
Patients should be cautioned about the risk of serotonin syndrome with the concomitant use of citalopram and triptans, tramadol or other serotonergic agents.
Although in controlled studies citalopram tablets have not been shown to impair psychomotor performance, any psychoactive drug may impair judgment, thinking, or motor skills, so patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that citalopram tablets therapy does not affect their ability to engage in such activities.
Patients should be told that, although citalopram tablets have not been shown in experiments with normal subjects to increase the mental and motor skill impairments caused by alcohol, the concomitant use of citalopram tablets and alcohol in depressed patients is not advised.
Patients should be advised to inform their physician if they are taking, or plan to take, any prescription or over-the-counter drugs, as there is a potential for interactions.
Patients should be cautioned about the concomitant use of citalopram and NSAIDs, aspirin, warfarin, or other drugs that affect coagulation since combined use of psychotropic drugs that interfere with serotonin reuptake and these agents has 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 breastfeeding an infant.
While patients may notice improvement with citalopram tablets therapy in 1 to 4 weeks, they should be advised to continue therapy as directed.
Prescribers or other health professionals should inform patients, their families, and their caregivers about the benefits and risks associated with treatment with citalopram 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 citalopram. 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 citalopram.
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.
Laboratory Tests
There are no specific laboratory tests recommended.
Drug Interactions
Serotonergic Drugs
Based on the mechanism of action of SNRIs and SSRIs including citalopram, and the potential for serotonin syndrome, caution is advised when citalopram 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
WARNINGS-Serotonin Syndrome). The concomitant use of citalopram with other SSRIs, SNRIs or tryptophan is not recommended (see
PRECAUTIONS - Drug Interactions).
Triptans
There have been rare postmarketing reports of serotonin syndrome with use of an SSRI and a triptan. If concomitant treatment of citalopram with a triptan is clinically warranted, careful observation of the patient is advised, particularly during treatment initiation and dose increases (see
WARNINGS - Serotonin Syndrome).
CNS Drugs
- Given the primary CNS effects of citalopram, caution should be used when it is taken in combination with other centrally acting drugs.
Alcohol - Although citalopram did not potentiate the cognitive and motor effects of alcohol in a clinical trial, as with other psychotropic medications, the use of alcohol by depressed patients taking citalopram tablets are not recommended.
Monoamine Oxidase Inhibitors (MAOIs)
- See
CONTRAINDICATIONS and
WARNINGS.
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 may potentiate the risk of bleeding. Altered anticoagulant effects, including increased bleeding, have been reported when SSRIs and SNRIs are coadministered with warfarin. Patients receiving warfarin therapy should be carefully monitored when citalopram is initiated or discontinued.
Cimetidine - In subjects who had received 21 days of 40 mg/day citalopram tablets, combined administration of 400 mg/day cimetidine for 8 days resulted in an increase in citalopram AUC and C
max of 43% and 39%, respectively. The clinical significance of these findings is unknown.
Digoxin – In subjects who had received 21 days of 40 mg/day citalopram tablets, combined administration of citalopram tablets and digoxin (single dose of 1 mg) did not significantly affect the pharmacokinetics of either citalopram or digoxin.
Lithium
- Coadministration of citalopram tablets (40 mg/day for 10 days) and lithium (30 mmol/day for 5 days) had no significant effect on the pharmacokinetics of citalopram or lithium. Nevertheless, plasma lithium levels should be monitored with appropriate adjustment to the lithium dose in accordance with standard clinical practice. Because lithium may enhance the serotonergic effects of citalopram, caution should be exercised when citalopram tablets and lithium are coadministered.
Pimozide – In a controlled study, a single dose of pimozide 2 mg co-administered with citalopram 40 mg given once daily for 11 days was associated with a mean increase in QTc values of approximately 10 msec compared to pimozide given alone. Citalopram did not alter the mean AUC or C
max of pimozide. The mechanism of this pharmacodynamic interaction is not known.
Theophylline
- Combined administration of citalopram tablets (40 mg/day for 21 days) and the CYP1A2 substrate theophylline (single dose of 300 mg) did not affect the pharmacokinetics of theophylline. The effect of theophylline on the pharmacokinetics of citalopram was not evaluated.
Sumatriptan
- There have been rare postmarketing reports describing patients with weakness, hyperreflexia, and incoordination following the use of a SSRI and sumatriptan. If concomitant treatment with sumatriptan and an SSRI (e.g., fluoxetine, fluvoxamine, paroxetine, sertraline, citalopram) is clinically warranted, appropriate observation of the patient is advised.
Warfarin
- Administration of 40 mg/day citalopram tablets for 21 days did not affect the pharmacokinetics of warfarin, a CYP3A4 substrate. Prothrombin time was increased by 5%, the clinical significance of which is unknown.
Carbamazepine
- Combined administration of citalopram tablets (40 mg/day for 14 days) and carbamazepine (titrated to 400 mg/day for 35 days) did not significantly affect the pharmacokinetics of carbamazepine, a CYP3A4 substrate. Although trough citalopram plasma levels were unaffected, given the enzyme-inducing properties of carbamazepine, the possibility that carbamazepine might increase the clearance of citalopram should be considered if the two drugs are coadministered.
Triazolam
- Combined administration of citalopram tablets (titrated to 40 mg/day for 28 days) and the CYP3A4 substrate triazolam (single dose of 0.25 mg) did not significantly affect the pharmacokinetics of either citalopram or triazolam.
Ketoconazole
- Combined administration of citalopram tablets (40 mg) and ketoconazole (200 mg) decreased the C
max and AUC of ketoconazole by 21% and 10%, respectively, and did not significantly affect the pharmacokinetics of citalopram.
CYP3A4 and 2C19 Inhibitors
- In vitro studies indicated that CYP3A4 and 2C19 are the primary enzymes involved in the metabolism of citalopram. However, coadministration of citalopram (40 mg) and ketoconazole (200 mg), a potent inhibitor of CYP3A4, did not significantly affect the pharmacokinetics of citalopram. Because citalopram is metabolized by multiple enzyme systems, inhibition of a single enzyme may not appreciably decrease citalopram clearance.
Metoprolol
- Administration of 40 mg/day citalopram tablets for 22 days resulted in a two-fold increasein the plasma levels of the beta-adrenergic blocker metoprolol. Increased metoprolol plasma levels have been associated with decreased cardioselectivity. Coadministration of citalopram tablets and metoprolol had no clinically significant effects on blood pressure or heart rate.
Imipramine and Other Tricyclic Antidepressants (TCAs)
- In vitro studies suggest that citalopram is a relatively weak inhibitor of CYP2D6. Coadministration of citalopram tablets (40 mg/day for 10 days) with the TCA imipramine (single dose of 100 mg), a substrate for CYP2D6, did not significantly affect the plasma concentrations of imipramine or citalopram. However, the concentration of the imipramine metabolite desipramine was increased by approximately 50%. The clinical significance of the desipramine change is unknown. Nevertheless, caution is indicated in the coadministration of TCAs with citalopram tablets.
Electroconvulsive Therapy (ECT) - There are no clinical studies of the combined use of electroconvulsive therapy (ECT) and citalopram tablets.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenesis
Citalopram was administered in the diet to NMRI/BOM strain mice and COBS WI strain rats for 18 and 24 months, respectively. There was no evidence for carcinogenicity of citalopram in mice receiving up to 240 mg/kg/day, which is equivalent to 20 times the maximum recommended human daily dose (MRHD) of 60 mg on a surface area (mg/m
2) basis. There was an increased incidence of small intestine carcinoma in rats receiving 8 or 24 mg/kg/day, doses which are approximately 1.3 and 4 times the MRHD, respectively, on a mg/m
2 basis. A no-effect dose for this finding was not established. The relevance of these findings to humans is unknown.
Mutagenesis
Citalopram was mutagenic in the
in vitro bacterial reverse mutation assay (Ames test) in 2 of 5 bacterial strains (Salmonella TA98 and TA1537) in the absence of metabolic activation. It was clastogenic in the
in vitro Chinese hamster lung cell assay for chromosomal aberrations in the presence and absence of metabolic activation. Citalopram was not mutagenic in the
in vitro mammalian forward gene mutation assay (HPRT) in mouse lymphoma cells or in a coupled
in vitro/in vivo unscheduled DNA synthesis (UDS) assay in rat liver. It was not clastogenic in the
in vitro chromosomal aberration assay in human lymphocytes or in two
in vivo mouse micronucleus assays.
Impairment of Fertility
When citalopram was administered orally to 16 male and 24 female rats prior to and throughout mating and gestation at doses of 32, 48, and 72 mg/kg/day, mating was decreased at all doses, and fertility was decreased at doses ≥ 32 mg/kg/day, approximately 5 times the MRHD of 60 mg/day on a body surface area (mg/m
2) basis. Gestation duration was increased at 48 mg/kg/day, approximately 8 times the MRHD.
Pregnancy
Pregnancy Category C
In animal reproduction studies, citalopram has been shown to have adverse effects on embryo/fetal and postnatal development, including teratogenic effects, when administered at doses greater than human therapeutic doses.
In two rat embryo/fetal development studies, oral administration of citalopram (32, 56, or 112 mg/kg/day) to pregnant animals during the period of organogenesis resulted in decreased embryo/fetal growth and survival and an increased incidence of fetal abnormalities (including cardiovascular and skeletal defects) at the high dose, which is approximately 18 times the MRHD of 60 mg/day on a body surface area (mg/m
2) basis. This dose was also associated with maternal toxicity (clinical signs, decreased body weight gain). The developmental, no-effect dose of 56 mg/kg/day is approximately 9 times the MRHD on a mg/m
2 basis. In a rabbit study, no adverse effects on embryo/fetal development were observed at doses of up to 16 mg/kg/day, or approximately 5 times the MRHD on a mg/m
2 basis. Thus, teratogenic effects were observed at a maternally toxic dose in the rat and were not observed in the rabbit.
When female rats were treated with citalopram (4.8, 12.8, or 32 mg/kg/day) from late gestation through weaning, increased offspring mortality during the first 4 days after birth and persistent offspring growth retardation were observed at the highest dose, which is approximately 5 times the MRHD on a mg/m
2 basis. The no-effect dose of 12.8 mg/kg/day is approximately 2 times the MRHD on a mg/m
2 basis. Similar effects on offspring mortality and growth were seen when dams were treated throughout gestation and early lactation at doses ≥ 24 mg/kg/day, approximately 4 times the MRHD on a mg/m
2 basis. A no-effect dose was not determined in that study.
There are no adequate and well-controlled studies in pregnant women; therefore, citalopram should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Nonteratogenic Effects
Neonates exposed to citalopram and other SSRIs or 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
WARNINGS).
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 citalopram 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 citalopram tablets on labor and delivery in humans is unknown.
Nursing Mothers
As has been found to occur with many other drugs, citalopram is excreted in human breast milk. There have been two reports of infants experiencing excessive somnolence, decreased feeding, and weight loss in association with breastfeeding from a citalopram-treated mother; in one case, the infant was reported to recover completely upon discontinuation of citalopram by its mother and in the second case, no follow-up information was available. The decision whether to continue or discontinue either nursing or citalopram tablets therapy should take into account the risks of citalopram exposure for the infant and the benefits of citalopram tablets treatment for the mother.
Pediatric Use
Safety and effectiveness in the pediatric population have not been established (see
BOX WARNING and
WARNINGS–-Clinical Worsening and Suicide Risk). Two placebo-controlled trials in 407 pediatric patients with MDD have been conducted with citalopram tablets, and the data were not sufficient to support a claim for use in pediatric patients. Anyone considering the use of citalopram tablets in a child or adolescent must balance the potential risks with the clinical need.
Geriatric Use
Of 4422 patients in clinical studies of citalopram tablets, 1357 were 60 and over, 1034 were 65 and over, and 457 were 75 and over. 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. Most elderly patients treated with citalopram tablets in clinical trials received daily doses between 20 and 40 mg (see
DOSAGE AND ADMINISTRATION).
SSRIs and SNRIs, including citalopram, have been associated with cases of clinically significant hyponatremia in elderly patients, who may be at greater risk for this adverse event (see
PRECAUTIONS, Hyponatremia).
In two pharmacokinetic studies, citalopram AUC was increased by 23% and 30%, respectively, in elderly subjects as compared to younger subjects, and its half-life was increased by 30% and 50%, respectively (see
CLINICAL PHARMACOLOGY).
20 mg/day is the recommended dose for most elderly patients (see
DOSAGE AND ADMINISTRATION).