Medication Guide: Citalopram

Uses and Indications

Citalopram is primarily prescribed for major depressive disorder (MDD). It may also be used off-label for anxiety disorders, obsessive-compulsive disorder (OCD), and panic disorder. This SSRI works by increasing serotonin levels in the brain.

Dosage and Administration

Citalopram is available in tablet form and as an oral solution. Dosage typically starts at 20 mg daily, with potential adjustments based on efficacy and tolerability. Maximum recommended dosage is 40 mg per day due to the risk of QT prolongation. It should be taken once daily, with or without food.

Mechanism of Action

Citalopram belongs to a class of drugs known as selective serotonin reuptake inhibitors (SSRIs). It enhances serotonin activity by inhibiting its reuptake into the presynaptic neuron. This leads to increased serotonin concentrations in the synaptic cleft, which helps improve mood.

Pharmacokinetics

Citalopram is well-absorbed orally, with peak plasma concentrations reached in approximately 4 hours. The elimination half-life is about 35 hours, making it suitable for once-daily dosing. It is metabolized in the liver and excreted primarily via the kidneys.

Drug Interactions

Citalopram may interact with other medications, including MAO inhibitors, other SSRIs, and blood thinners. Caution should be exercised when combining with drugs known to prolong the QT interval. It can also affect the metabolism of other drugs by inhibiting the cytochrome P450 enzyme system.

Side Effects Overview

Common side effects include nausea, dry mouth, and fatigue. Some patients may experience sexual dysfunction, such as reduced libido or anorgasmia. Serious side effects like QT interval prolongation and serotonin syndrome require immediate medical attention.

Patient Counseling Information

Patients should be informed about the potential for dizziness and drowsiness, especially when starting treatment. They should avoid alcohol during treatment. Abrupt cessation can lead to withdrawal symptoms; a gradual dose reduction is recommended when discontinuing therapy.

Pregnancy and Lactation

Citalopram falls under Pregnancy Category C, meaning risk to the fetus cannot be ruled out. It is excreted in breast milk; nursing mothers should weigh the potential benefits and risks. Close monitoring is advised during pregnancy and lactation.

Contraindications

Citalopram is contraindicated in patients with known hypersensitivity to the drug. It should not be used concomitantly with MAO inhibitors or within 14 days of discontinuing an MAOI. It is also contraindicated in patients with congenital long QT syndrome.

Monitoring Parameters

Regular monitoring of QT interval through ECG is recommended, especially in patients with risk factors for QT prolongation. Liver function tests should be performed periodically due to metabolism in the liver. Renal function tests may also be needed in patients with renal impairment.

Special Populations

In elderly patients, a lower starting dose of 10 mg is recommended due to the increased risk of adverse effects. For patients with hepatic impairment, the maximum recommended dose is 20 mg daily. Children and adolescents should be treated with caution, as efficacy and safety are not well-established.

Storage and Stability

Store citalopram tablets and oral solution at room temperature, away from excess heat and moisture. The medication should be kept out of reach of children. Tablets should be stored in their original container to prevent deterioration from exposure to air and light.

Switching Antidepressants

Transitioning from other antidepressants to citalopram should be done cautiously. A washout period is usually necessary when switching from MAO inhibitors to avoid serotonin syndrome. Dose adjustments may be required depending on the previous medication used.

Alternative Brand Names

Citalopram is marketed under multiple brand names, including Celexa. Generic versions are also available, offering cost-effective alternatives. Patients should confirm with their pharmacist that they are receiving the correct medication.

Pharmacogenomics Considerations

Genetic polymorphisms in the cytochrome P450 enzyme system can affect citalopram metabolism. Genetic testing may be considered to identify patients who are poor metabolizers or ultra-rapid metabolizers. This information can help tailor the dosage for optimal efficacy and safety.

Overdose Management

Symptoms of citalopram overdose include dizziness, tremor, and altered mental status. In severe cases, cardiac arrhythmias and seizures can occur. Treatment involves supportive care and monitoring of cardiac and respiratory function. Activated charcoal may be administered to reduce absorption.

Counseling on Missed Dose

Patients should be advised to take a missed dose as soon as they remember. If it is almost time for the next dose, they should skip the missed dose and resume their regular schedule. Double dosing to compensate for a missed dose is not recommended.