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All about: Citalopram

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Generic Name: Citalopram hydrobromide
Dosage Form: Tablets

Suicidality and Antidepressant Drugs

Antidepressants increased the risk compared to placebo of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults in short-term studies of major depressive disorder (MDD) and other psychiatric disorders. Anyone considering the use of Citalopram or any other antidepressant in a child, adolescent, or young adult must balance this risk with the clinical need. Short-term studies did not show an increase in the risk of suicidality with antidepressants compared to placebo in adults beyond age 24; there was a reduction in risk with antidepressants compared to placebo in adults aged 65 and older. Depression and certain other psychiatric disorders are themselves associated with increases in the risk of suicide. Patients of all ages who are started on antidepressant therapy should be monitored appropriately and observed closely for clinical worsening, suicidality, or unusual changes in behavior. Families and caregivers should be advised of the need for close observation and communication with the prescriber. Citalopram is not approved for use in pediatric patients. (See Warnings: Clinical Worsening and Suicide Risk, Precautions: Information for Patients, and Precautions: Pediatric Use)

Citalopram Description

Citalopram HBr is a selective serotonin reuptake inhibitor (SSRI) with a chemical structure unrelated to that of other SSRIs or of tricyclic, tetracyclic, or other available antidepressant agents. Citalopram HBr is a racemic bicyclic phthalane derivative designated (±)-1-(3-dimethylaminopropyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile, HBr with the following structural formula:

Citalopram HBr occurs as a fine, white to off-white powder with a molecular formula of C20H22BrFN2O and a molecular weight of 405.35. Citalopram HBr is sparingly soluble in water and soluble in ethanol.

Each Citalopram HBr Tablet for oral administration contains Citalopram HBr equivalent to 10 mg, 20 mg, or 40 mg Citalopram base. Each tablet also contains the following inactive ingredients: corn starch, croscarmellose sodium, hypromellose, magnesium stearate, mannitol, microcrystalline cellulose, polyethylene glycol, and titanium dioxide.

Citalopram - Clinical Pharmacology

Pharmacodynamics

The mechanism of action of Citalopram HBr as an antidepressant is presumed to be linked to potentiation of serotonergic activity in the central nervous system resulting from its inhibition of CNS neuronal reuptake of serotonin (5-HT). In vitro and in vivo studies in animals suggest that Citalopram is a highly selective serotonin reuptake inhibitor (SSRI) with minimal effects on norepinephrine (NE) and dopamine (DA) neuronal reuptake. Tolerance to the inhibition of 5-HT uptake is not induced by long term (14 day) treatment of rats with Citalopram. Citalopram is a racemic mixture (50/50), and the inhibition of 5-HT reuptake by Citalopram is primarily due to the (S)-enantiomer.

Citalopram has no or very low affinity for 5-HT1A, 5-HT2A, dopamine D1 and D2, α1-, α2, and β-adrenergic, histamine H1, gamma aminobutyric acid (GABA), muscarinic cholinergic, and benzodiazepine receptors. Antagonism of muscarinic, histaminergic and adrenergic receptors has been hypothesized to be associated with various anticholinergic, sedative and cardiovascular effects of other psychotropic drugs.

Pharmacokinetics

The single- and multiple-dose pharmacokinetics of Citalopram are linear and dose-proportional in a dose range of 10-60 mg/day. Biotransformation of Citalopram is mainly hepatic, with a mean terminal half-life of about 35 hours. With once daily dosing, steady state plasma concentrations are achieved within approximately one week. At steady state, the extent of accumulation of Citalopram in plasma, based on the half-life, is expected to be 2.5 times the plasma concentrations observed after a single dose.

Absorption and Distribution: Following a single oral dose (40 mg tablet) of Citalopram, peak blood levels occur at about 4 hours. The absolute bioavailability of Citalopram was about 80% relative to an intravenous dose and absorption is not affected by food. The volume of distribution of Citalopram is about 12 L/kg and the binding of Citalopram (CT), demethylCitalopram (DCT) and didemethylCitalopram (DDCT) to human plasma proteins is about 80%.

Metabolism and Elimination: Following intravenous administrations of Citalopram, the fraction of drug recovered in the urine as Citalopram and DCT was about 10% and 5%, respectively. The systemic clearance of Citalopram was 330 mL/min, with approximately 20% of that due to renal clearance.

Citalopram is metabolized to demethylCitalopram (DCT), didemethylCitalopram (DDCT), Citalopram-N-oxide and a deaminated propionic acid derivative. In humans, unchanged Citalopram is the predominant compound in plasma. At steady state, the concentrations of Citalopram’s metabolites, DCT and DDCT, in plasma are approximately one-half and one-tenth, respectively, that of the parent drug. In vitro studies show that Citalopram is at least 8 times more potent than its metabolites in the inhibition of serotonin reuptake, suggesting that the metabolites evaluated do not likely contribute significantly to the antidepressant actions of Citalopram.

In vitro studies using human liver microsomes indicated that CYP3A4 and CYP2C19 are the primary isozymes involved in the N-demethylation of Citalopram.

Population Subgroups: Age – Citalopram pharmacokinetics in subjects ~60 years of age were compared to younger subjects in two normal volunteer studies. In a single dose study, Citalopram AUC and half-life were increased in the elderly subjects by 30% and 50%, respectively, whereas in a multiple dose study they were increased by 23% and 30%, respectively. 20 mg is the recommended dose for most elderly patients (see DOSAGE AND ADMINISTRATION).

Gender – In three pharmacokinetic studies (total N=32), Citalopram AUC in women was one and a half to two times that in men. This difference was not observed in five other pharmacokinetic studies (total N=114). In clinical studies, no differences in steady state serum Citalopram levels were seen between men (N=237) and women (N=388). There were no gender differences in the pharmacokinetics of DCT and DDCT. No adjustment of dosage on the basis of gender is recommended.

Reduced hepatic function – Citalopram oral clearance was reduced by 37% and half-life was doubled in patients with reduced hepatic function compared to normal subjects. 20 mg is the recommended dose for most hepatically impaired patients (see DOSAGE AND ADMINISTRATION).

Reduced renal function – In patients with mild to moderate renal function impairment, oral clearance of Citalopram was reduced by 17% compared to normal subjects. No adjustment of dosage for such patients is recommended. No information is available about the pharmacokinetics of Citalopram in patients with severely reduced renal function (creatinine clearance <20 mL/min).

Drug-Drug Interactions: In vitro enzyme inhibition data did not reveal an inhibitory effect of Citalopram on CYP3A4, -2C9, or -2E1, but did suggest that it is a weak inhibitor of CYP-1A2, -2D6, and -2C19. Citalopram would be expected to have little inhibitory effect on in vivo metabolism mediated by these cytochromes. However, in vivo data to address this question are limited.

Since CYP3A4 and 2C19 are the primary enzymes involved in the metabolism of Citalopram, it is expected that potent inhibitors of 3A4, e.g., ketoconazole, itraconazole, and macrolide antibiotics, and potent inhibitors of CYP2C19, e.g., omeprazole, might decrease the clearance of Citalopram. However, coadministration of Citalopram and the potent 3A4 inhibitor ketoconazole 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. Citalopram steady state levels were not significantly different in poor metabolizers and extensive 2D6 metabolizers after multiple dose administration of Citalopram, suggesting that coadministration, with Citalopram, of a drug that inhibits CYP2D6, is unlikely to have clinically significant effects on Citalopram metabolism. See Drug Interactions under PRECAUTIONS for more detailed information on available drug interaction data.

Clinical Efficacy Trials

The efficacy of Citalopram as a treatment for depression was established in two placebo-controlled studies (of 4 to 6 weeks in duration) in adult outpatients (ages 18-66) meeting DSM-III or DSM-III-R criteria for major depression. Study 1, a 6-week trial in which patients received fixed Citalopram HBr doses of 10, 20, 40, and 60 mg/day, showed that Citalopram HBr at doses of 40 and 60 mg/day was effective as measured by the Hamilton Depression Rating Scale (HAMD) total score, the HAMD depressed mood item (Item 1), the Montgomery Asberg Depression Rating Scale, and the Clinical Global Impression (CGI) Severity scale. This study showed no clear effect of the 10 and 20 mg/day doses, and the 60 mg/day dose was not more effective than the 40 mg/day dose. In study 2, a 4-week, placebo-controlled trial in depressed patients, of whom 85% met criteria for melancholia, the initial dose was 20 mg/day, followed by titration to the maximum tolerated dose or a maximum dose of 80 mg/day. Patients treated with Citalopram showed significantly greater improvement than placebo patients on the HAMD total score, HAMD item 1, and the CGI Severity score. In three additional placebo-controlled depression trials, the difference in response to treatment between patients receiving Citalopram and patients receiving placebo was not statistically significant, possibly due to high spontaneous response rate, smaller sample size, or, in the case of one study, too low a dose.

In two long-term studies, depressed patients who had responded to Citalopram HBr during an initial 6 or 8 weeks of acute treatment (fixed doses of 20 or 40 mg/day in one study and flexible doses of 20-60 mg/day in the second study) were randomized to continuation of Citalopram or to placebo. In both studies, patients receiving continued Citalopram treatment experienced significantly lower relapse rates over the subsequent 6 months compared to those receiving placebo. In the fixed dose study, the decreased rate of depression relapse was similar in patients receiving 20 or 40 mg/day of Citalopram.

Analyses of the relationship between treatment outcome and age, gender, and race did not suggest any differential responsiveness on the basis of these patient characteristics.

Comparison of Clinical Trial Results: Highly variable results have been seen in the clinical development of all antidepressant drugs. Furthermore, in those circumstances when the drugs have not been studied in the same controlled clinical trial(s), comparisons among the results of studies evaluating the effectiveness of different antidepressant drug products are inherently unreliable. Because conditions of testing (e.g., patient samples, investigators, doses of the treatments administered and compared, outcome measures, etc.) vary among trials, it is virtually impossible to distinguish a difference in drug effect from a difference due to one of the confounding factors just enumerated.

Indications and Usage for Citalopram

Citalopram HBr is indicated for the treatment of depression.

The efficacy of Citalopram HBr in the treatment of depression was established in 4-6 week controlled trials of outpatients whose diagnosis corresponded most closely to the DSM-III and DSM-III-R category of major depressive disorder (see CLINICAL PHARMACOLOGY).

A major depressive episode (DSM-IV) implies a prominent and relatively persistent (nearly every day for at least 2 weeks) depressed or dysphoric mood that usually interferes with daily functioning, and includes at least five of the following nine symptoms: depressed mood, loss of interest in usual activities, significant change in weight and/or appetite, insomnia or hypersomnia, psychomotor agitation or retardation, increased fatigue, feelings of guilt or worthlessness, slowed thinking or impaired concentration, a suicide attempt or suicidal ideation.

The antidepressant action of Citalopram in hospitalized depressed patients has not been adequately studied.

The efficacy of Citalopram in maintaining an antidepressant response for up to 24 weeks following 6 to 8 weeks of acute treatment was demonstrated in two placebo-controlled trials (see CLINICAL PHARMACOLOGY). Nevertheless, the physician who elects to use Citalopram for extended periods should periodically re-evaluate the long-term usefulness of the drug for the individual patient.

Contraindications

Concomitant use in patients taking monoamine oxidase inhibitors (MAOI’s) is contraindicated (see WARNINGS). Concomitant use in patients taking pimozide is contraindicated (see PRECAUTIONS).

Citalopram HBr is contraindicated in patients with a hypersensitivity to Citalopram or any of the inactive ingredients in Citalopram HBr tablets.

Warnings

Clinical Worsening and Suicide Risk

Patients with major depressive disorder (MDD), both adult and pediatric, may experience worsening of their depression and/or the emergence of suicidal ideation and behavior (suicidality) or unusual changes in behavior, whether or not they are taking antidepressant medications, and this risk may persist until significant remission occurs. Suicide is a known risk of depression and certain other psychiatric disorders, and these disorders themselves are the strongest predictors of suicide. There has been a long-standing concern, however, that antidepressants may have a role in inducing worsening of depression and the emergence of suicidality in certain patients during the early phases of treatment. Pooled analyses of short-term placebo-controlled trials of antidepressant drugs (SSRIs and others) showed that these drugs increase the risk of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults (ages 18-24) with major depressive disorder (MDD) and other psychiatric disorders. Short-term studies did not show an increase in the risk of suicidality with antidepressants compared to placebo in adults beyond age 24; there was a reduction with antidepressants compared to placebo in adults aged 65 and older.

The pooled analyses of placebo-controlled trials in children and adolescents with MDD, obsessive compulsive disorder (OCD), or other psychiatric disorders included a total of 24 short-term trials of 9 antidepressant drugs in over 4400 patients. The pooled analyses of placebo-controlled trials in adults with MDD or other psychiatric disorders included a total of 295 short-term trials (median duration of 2 months) of 11 antidepressant drugs in over 77,000 patients. There was considerable variation in risk of suicidality among drugs, but a tendency toward an increase in the younger patients for almost all drugs studied. There were differences in absolute risk of suicidality across the different indications, with the highest incidence in MDD. The risk differences (drug vs placebo), however, were relatively stable within age strata and across indications. These risk differences (drug-placebo difference in the number of cases of suicidality per 1000 patients treated) are provided in Table 1:

Table 1
Age Range Drug-Placebo Difference in Number of Cases of Suicidality per 1000 Patients
Drug-Related Increases
<18 14 additional cases
18-24 5 additional cases
Drug-Related Decreases
25-64 1 fewer case
≥65 6 fewer cases

No suicides occurred in any of the pediatric trials. There were suicides in the adult trials, but the number was not sufficient to reach any conclusion about drug effect on suicide.

It is unknown whether the suicidality risk extends to longer-term use, i.e., beyond several months. However, there is substantial evidence from placebo-controlled maintenance trials in adults with depression that the use of antidepressants can delay the recurrence of depression.

All patients being treated with antidepressants for any indication should be monitored appropriately and observed closely for clinical worsening, suicidality, and unusual changes in behavior, especially during the initial few months of a course of drug therapy, or at times of dose changes, either increases or decreases.

The following symptoms, anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia (psychomotor restlessness), hypomania, and mania, have been reported in adult and pediatric patients being treated with antidepressants for major depressive disorder as well as for other indications, both psychiatric and nonpsychiatric. Although a causal link between the emergence of such symptoms and either the worsening of depression and/or the emergence of suicidal impulses has not been established, there is concern that such symptoms may represent precursors to emerging suicidality.

Consideration should be given to changing the therapeutic regimen, including possibly discontinuing the medication, in patients whose depression is persistently worse, or who are experiencing emergent suicidality or symptoms that might be precursors to worsening depression or suicidality, especially if these symptoms are severe, abrupt in onset, or were not part of the patient's presenting symptoms.

If the decision has been made to discontinue treatment, medication should be tapered, as rapidly as is feasible, but with recognition that abrupt discontinuation can be associated with certain symptoms (see PRECAUTIONS and DOSAGE AND ADMINISTRATION—Discontinuation of Treatment with Citalopram, for a description of the risks of discontinuation of Citalopram.)

Families and caregivers of patients being treated with antidepressants for major depressive disorder or other indications, both psychiatric and nonpsychiatric, should be alerted about the need to monitor patients for the emergence of agitation, irritability, unusual changes in behavior, and the other symptoms described above, as well as the emergence of suicidality, and to report such symptoms immediately to health care providers. Such monitoring should include daily observation by families and caregivers. Prescriptions for Citalopram should be written for the smallest quantity of tablets consistent with good patient management, in order to reduce the risk of overdose.

Screening Patients for Bipolar Disorder: A major depressive episode may be the initial presentation of bipolar disorder. It is generally believed (though not established in controlled trials) that treating such an episode with an antidepressant alone may increase the likelihood of precipitation of a mixed/manic episode in patients at risk for bipolar disorder. Whether any of the symptoms described above represent such a conversion is unknown. However, prior to initiating treatment with an antidepressant, patients with depressive symptoms should be adequately screened to determine if they are at risk for bipolar disorder; such screening should include a detailed psychiatric history, including a family history of suicide, bipolar disorder, and depression. It should be noted that Citalopram is not approved for use in treating bipolar depression.

Potential for Interaction with Monoamine Oxidase Inhibitors

In patients receiving serotonin reuptake inhibitor drugs in combination with a monoamine oxidase inhibitor (MAOI), there have been reports of serious, sometimes fatal, reactions including hyperthermia, rigidity, myoclonus, autonomic instability with possible rapid fluctuations of vital signs, and mental status changes that include extreme agitation progressing to delirium and coma. These reactions have also been reported in patients who have recently discontinued SSRI treatment and have been started on an MAOI. Some cases presented with features resembling neuroleptic malignant syndrome. Furthermore, limited animal data on the effects of combined use of SSRIs and MAOI’s suggest that these drugs may act synergistically to elevate blood pressure and evoke behavioral excitation. Therefore, it is recommended that Citalopram HBr should not be used in combination with an MAOI, or within 14 days of discontinuing treatment with an MAOI. Similarly, at least 14 days should be allowed after stopping Citalopram HBr before starting an MAOI.

Precautions

General

Discontinuation of Treatment with Citalopram

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

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 Citalopram with NSAIDS, aspirin, or other drugs that affect coagulation.

Hyponatremia: Cases of hyponatremia and SIADH (syndrome of inappropriate antidiuretic hormone secretion) have been reported in association with Citalopram treatment. All patients with these events have recovered with discontinuation of Citalopram and/or medical intervention.

Hyponatremia and SIADH have also been reported in associated with other marketed drugs effective in the treatment of major depressive disorder.

Activation of Mania/Hypomania: In placebo-controlled trials of Citalopram, some of which included patients with bipolar disorder, activation of mania/hypomania was reported in 0.2% of 1063 patients treated with Citalopram 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 should be used cautiously in patients with a history of mania.

Seizures: Although anticonvulsant effects of Citalopram have been observed in animal studies, Citalopram has 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, seizures occurred in 0.3% of patients treated with Citalopram (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 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 in doses of 40 mg/day did not produce impairment of intellectual function or psychomotor performance. Because any psychoactive drug may impair judgement, thinking, or motor skills, however, patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that Citalopram therapy does not affect their ability to engage in such activities.

Use in Patients with Concomitant Illness: Clinical experience with Citalopram in patients with certain concomitant systemic illnesses is limited. Caution is advisable in using Citalopram in patients with diseases or conditions that produce altered metabolism or hemodynamic responses.

Citalopram has 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 in clinical trials were evaluated and the data indicate that Citalopram is 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 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, it 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:

Although in controlled studies Citalopram has not been shown to impair psychomotor performance, any psychoactive drug may impair judgment, thinking or motor skills, and so patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that Citalopram therapy does not affect their ability to engage in such activities.

Patients should be told that, although Citalopram has not been shown in experiments with normal subjects to increase the mental and motor skill impairments caused by alcohol, the concomitant use of Citalopram 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, or other drugs that affect coagulation since the 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 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

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 is not recommended.

Monoamine Oxidase Inhibitors (MAOI’s) – 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 potentiated the risk of bleeding. Thus, patients should be cautioned about the use of such drugs concurrently with Citalopram.

Cimetidine – In subjects who had received 21 days of 40 mg/day Citalopram, combined administration of 400 mg/day cimetidine for 8 days resulted in an increase in Citalopram AUC and Cmax 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, combined administration of Citalopram and digoxin (single dose of 1 mg) did not significantly affect the pharmacokinetics of either Citalopram or digoxin.

Lithium – Coadministration of Citalopram (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 and lithium are coadministered.

Pimozide – In a controlled study, a single dose of pimozide 2 mg coadministered 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 Cmax of pimozide.  The mechanism of this pharmacodynamic interaction is not known.

Theophylline – Combined administration of Citalopram (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 selective serotonin reuptake inhibitor (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 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 (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 (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 (40 mg) and ketoconazole (200 mg) decreased the Cmax 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 for 22 days resulted in a two-fold increase in the plasma levels of the beta-adrenergic blocker metoprolol. Increased metoprolol plasma levels have been associated with decreased cardioselectivity. Coadministration of Citalopram 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 (40 mg/day for 10 days) with the tricyclic antidepressant 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 TCA’s with Citalopram.

Electroconvulsive Therapy (ECT) – There are no clinical studies of the combined use of electroconvulsive therapy (ECT) and Citalopram.

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/m2) 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 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 maximum recommended human dose (MRHD) of 60 mg/day on a body surface area (mg/m2) 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 maximum recommended human dose (MRHD) of 60 mg/day on a body surface area (mg/m2) 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/m2 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/m2 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/m2 basis. The no effect dose of 12.8 mg/kg/day is approximately 2 times the MRHD on a mg/m2 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/m2 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.

Pregnancy-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).

When treating a pregnant woman with Citalopram during the third trimester, the physician should carefully consider the potential risks and benefits of treatment (see DOSAGE AND ADMINISTRATION).

Labor and Delivery

The effect of Citalopram 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 breast feeding 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 therapy should take into account the risks of Citalopram exposure for the infant and the benefits of Citalopram treatment for the mother.

Pediatric Use

Safety and effectiveness in pediatric patients 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, and the data were not sufficient to support a claim for use in pediatric patients.  Anyone considering the use of Citalopram in a child or adolescent must balance the potential risks with the clinical need.

Geriatric Use

Of 4422 patients in clinical studies of Citalopram, 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 in clinical trials received daily doses between 20 and 40 mg (see DOSAGE AND ADMINISTRATION).

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).

Adverse Reactions

The premarketing development program for Citalopram included Citalopram exposures in patients and/or normal subjects from 3 different groups of studies: 429 normal subjects in clinical pharmacology/pharmacokinetic studies; 4422 exposures from patients in controlled and uncontrolled clinical trials, corresponding to approximately 1370 patient exposure years. There were, in addition, over 19,000 exposures from mostly open-label, European postmarketing studies. The conditions and duration of treatment with Citalopram varied greatly and included (in overlapping categories) open-label and double-blind studies, inpatient and outpatient studies, fixed-dose and dose-titration studies, and short-term and long-term exposure. Adverse reactions were assessed by collecting adverse events, results of physical examinations, vital signs, weights, laboratory analyses, ECGs, and results of ophthalmologic examinations.

Adverse events during exposure were obtained primarily by general inquiry and recorded by clinical investigators using terminology of their own choosing. Consequently, it is not possible to provide a meaningful estimate of the proportion of individuals experiencing adverse events without first grouping similar types of events into a smaller number of standardized event categories. In the tables and tabulations that follow, standard World Health Organization (WHO) terminology has been used to classify reported adverse events.

The stated frequencies of adverse events represent the proportion of individuals who experienced, at least once, a treatment-emergent adverse event of the type listed. An event was considered treatment-emergent if it occurred for the first time or worsened while receiving therapy following baseline evaluation.

Adverse Findings Observed in Short-Term, Placebo-Controlled Trials

Adverse Events Associated with Discontinuation of Treatment: Among 1063 depressed patients who received Citalopram at doses ranging from 10 to 80 mg/day in placebo-controlled trials of up to 6 weeks in duration, 16% discontinued treatment due to an adverse event, as compared to 8% of 446 patients receiving placebo. The adverse events associated with discontinuation and considered drug-related (i.e., associated with discontinuation in at least 1% of Citalopram-treated patients at a rate at least twice that of placebo) are shown in TABLE 2. It should be noted that one patient can report more than one reason for discontinuation and be counted more than once in this table.

TABLE 2 Adverse Events Associated with Discontinuation of Treatment in Short-Term, Placebo-Controlled, Depression Trials
Percentage of Patients Discontinuing
Due to Adverse Event
Citalopram Placebo
(N=1063) (N=446)
Body System/Adverse Event
General
  Asthenia 1% <1%
Gastrointestinal Disorders
  Nausea 4% 0%
  Dry Mouth 1% <1%
  Vomiting 1% 0%
Central and Peripheral
Nervous System Disorders
  Dizziness 2% <1%
Psychiatric Disorders
  Insomnia 3% 1%
  Somnolence 2% 1%
  Agitation 1% <1%

Adverse Events Occurring at an Incidence of 2% or More Among Citalopram-Treated Patients

Table 3 enumerates the incidence, rounded to the nearest percent, of treatment emergent adverse events that occurred among 1063 depressed patients who received Citalopram at doses ranging from 10 to 80 mg/day in placebo-controlled trials of up to 6 weeks in duration. Events included are those occurring in 2% or more of patients treated with Citalopram and for which the incidence in patients treated with Citalopram was greater than the incidence in placebo-treated patients.

The prescriber should be aware that these figures cannot be used to predict the incidence of adverse events in the course of usual medical practice where patient characteristics and other factors differ from those which prevailed in the clinical trials. Similarly, the cited frequencies cannot be compared with figures obtained from other clinical investigations involving different treatments, uses, and investigators. The cited figures, however, do provide the prescribing physician with some basis for estimating the relative contribution of drug and non-drug factors to the adverse event incidence rate in the population studied.

The only commonly observed adverse event that occurred in Citalopram patients with an incidence of 5% or greater and at least twice the incidence in placebo patients was ejaculation disorder (primarily ejaculatory delay) in male patients (see TABLE 3).

TABLE 3 Treatment-Emergent Adverse Events: Incidence in Placebo-Controlled Clinical Trials*
(Percentage of Patients Discontinuing)
Body System/Adverse Event Citalopram Placebo
(N=1063) (N=446)
*Events reported by at least 2% of patients treated with Citalopram are reported, except for the following events which had an incidence on placebo ~ Citalopram: headache, asthenia, dizziness, constipation, palpitation, vision abnormal, sleep disorder, nervousness, pharyngitis, micturition disorder, back pain.
1Denominator used was for females only (N=638 Citalopram; N=252 placebo).
2Primarily ejaculatory delay.
3Denominator used was for males only (N=425 Citalopram; N=194 placebo).
Autonomic Nervous System Disorders
  Dry Mouth 20% 14%
  Sweating Increased 11% 9%
Central & Peripheral Nervous
System Disorders
  Tremor 8% 6%
Gastrointestinal Disorders
  Nausea 21% 14%
  Diarrhea 8% 5%
  Dyspepsia 5% 4%
  Vomiting 4% 3%
  Abdominal Pain 3% 2%
General
  Fatigue 5% 3%
  Fever 2% <1%
Musculoskeletal System Disorders
  Arthralgia 2%

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