Related Experiment Video

Updated: Aug 11, 2026

A High-Throughput Luciferase Assay to Evaluate Proteolysis of the Single-Turnover Protease PCSK9
08:14

A High-Throughput Luciferase Assay to Evaluate Proteolysis of the Single-Turnover Protease PCSK9

Published on: August 28, 2018

Decreased citalopram concentration caused by enzyme induction effect of rifampin: a case report

Jiajia Liu1,2, Jinmeng Li1, Ren Zheng1

  • 1Department of Pharmacy, Zhejiang Hospital of Integrated Traditional Chinese and Western Medicine, Hangzhou, Zhejiang Province, China.

Therapeutic Advances in Psychopharmacology
|March 28, 2025
PubMed

Insights

Rifampin, used for tuberculosis, can significantly reduce citalopram levels in patients with depression. This drug interaction may require dosage adjustments for effective treatment.

Area of Science:

  • Pharmacology
  • Clinical Pharmacy
  • Drug Interactions

Background:

  • Citalopram, a selective serotonin reuptake inhibitor, treats depression and anxiety disorders.
  • Rifampin, an antibiotic for tuberculosis, is known to induce cytochrome P450 enzymes.
  • Potential drug interactions between rifampin and citalopram are not well-documented.

Observation:

  • A 76-year-old patient on long-term citalopram experienced worsening depression, insomnia, and hopelessness after two months of rifampin treatment.
  • Therapeutic drug monitoring revealed citalopram plasma concentration (8.19 ng/mL) below the effective range (50-110 ng/mL).

Findings:

  • Rifampin significantly reduced citalopram plasma concentrations, indicating a clinically significant drug interaction.
  • Increasing citalopram dosage to 40 mg daily improved the patient's depressive symptoms.

Implications:

  • This case highlights the potential for rifampin to decrease citalopram efficacy due to CYP enzyme induction.
  • Clinicians should consider monitoring citalopram levels in patients concurrently treated with rifampin.
  • Therapeutic drug monitoring and dose adjustment may be necessary to manage this interaction effectively.
Keywords:
citalopramdrug interactionsenzyme inductionrifampintherapeutic drug monitoring

More Related Videos

Murine Surgical Model of Topical Elastase Induced Descending Thoracic Aortic Aneurysm08:33

Murine Surgical Model of Topical Elastase Induced Descending Thoracic Aortic Aneurysm

Published on: August 24, 2019

Split-Luciferase Reassembly Assay to Measure Endoplasmic Reticulum-Mitochondria Contacts in Live Cells09:09

Split-Luciferase Reassembly Assay to Measure Endoplasmic Reticulum-Mitochondria Contacts in Live Cells

Published on: October 11, 2024

Related Concept Videos

Time Course of Drug Effect01:14

Time Course of Drug Effect

The progression of a drug's impact can be analyzed by examining both the concentration-time course and the effect-time course. The concentration-time course is determined by the drug's half-life and is influenced by factors such as its pharmacokinetics, including absorption, distribution, metabolism, and elimination. The effect of the drug is often related to its concentration in the plasma and is calculated using the maximum drug effect and the plasma concentration that generates 50 percent of...
Antidepressant Drugs: Overview01:25

Antidepressant Drugs: Overview

Antidepressant drugs are a class of medications primarily used for treating various mood disorders, including major depression, anxiety disorders, and other related conditions. These medicines work by modulating the neurotransmitter balance within the brain, alleviating depressive symptoms. Antidepressants can be broadly categorized into several groups according to their mechanism of action and chemical structure: Selective Serotonin Reuptake Inhibitors (SSRIs), Serotonin-Norepinephrine...
Nonlinear Pharmacokinetics: Dependence of Elimination Half-Life and Dose Clearance01:23

Nonlinear Pharmacokinetics: Dependence of Elimination Half-Life and Dose Clearance

The elimination half-life and drug clearance of drugs following nonlinear kinetics can vary with dosage. The Michaelis-Menten parameters and drug concentration influence these factors. As the dose increases, the elimination half-life tends to lengthen, resulting in a reduction in clearance and a disproportionately larger area under the curve. The total clearance can be derived from the Michaelis-Menten equation for drugs following a one-compartment model.
A study on guinea pigs examined the...
Pharmacokinetics: Drug–Drug Interactions01:25

Pharmacokinetics: Drug–Drug Interactions

Drug interactions occur when the pharmacological effect of one drug is altered by another substance, either enhancing or diminishing its activity. The drug whose activity is altered is known as the object drug, and the substance causing the alteration is called the agent drug or the precipitant. The net effects of these interactions are mostly undesirable, leading to decreased effectiveness or increased adverse effects. In rare cases, interactions can be beneficial, such as the enhanced...
Effect of Hepatic Disease on Pharmacokinetics: Dose Adjustments Due to Hepatic Impairment01:08

Effect of Hepatic Disease on Pharmacokinetics: Dose Adjustments Due to Hepatic Impairment

Hepatic impairment, characterized by decreased liver function, does not uniformly mandate adjustments in drug dosage. Whether dosage modifications are necessary depends on various factors related to the drug's metabolism and elimination pathways. If a drug is primarily excreted via the kidneys and bypasses significant hepatic processing, if it undergoes minimal metabolic transformation in the liver, or if it is volatile and primarily expelled through the lungs, dose adjustments may not be...
Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes01:28

Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes

Cytochrome P450 (CYP450) enzymes are a superfamily of heme-containing monooxygenases that play a pivotal role in Phase I drug metabolism by catalyzing oxidation and reduction reactions.These enzymes transform lipophilic xenobiotics into more hydrophilic metabolites, facilitating subsequent Phase II conjugation and eventual excretion. The CYP450 family is classified into families (e.g., CYP1–CYP3) and subfamilies (e.g., CYP2A, CYP2C), based on amino acid sequence homology.CYP450 isoenzymes,...