Potential Drug Interactions with Thioridazine in Patients with Schizophrenia in Taiwan： An analysis of National Health Insurance Research Database
Date Issued
2005
Date
2005
Author(s)
Chen, Tzu-Ying
DOI
zh-TW
Abstract
Background: Drug-drug interactions (DDIs) may contribute to the occurance of adverse drug reactions, and unfortunately may cause death. It is one of the major concerns in clinical practice. It has been well-documented that some antipsychotics may cause QT interval prolongation or torsade de pointes leading to sudden death. The potential cardiotoxicity of thioridazine, in which drug interactions may play an important role, has caught lots of attention than other antipsychotics. The bulletins of the health regulatory agencies in many countries have continuously provided warnings with thioridazine to alert the potential cardiotoxicity of thioridazine since July, 2000. Drugs that may inhibit CYP 2D6 or prolong QT interval are considered as contraindications to combined use with thioridazine.
Objective : The objective of this study is to evaluate potential significant DDIs with thioridazine in patients with schizophrenia from 1997 to 2001 in Taiwan using National Health Insurance Research Database –
Psychiatric Inpatient Medical Claim Dataset (PIMC).
Method:Criteria for DDIs regarding thioridazine was established based on the information from the MICROMEDEX® software program and Drug Interaction Facts. Patients with schizophrenia, who were prescribed thioridazine in the ambulatory settings from 1997 to 2001 based on the PIMC, were enrolled in this study. Concomitant administration is defined when the dates of prescriptions of drug interaction pairs were overlapped.
Results: Our results showed that interactive drugs that most frequently combined with thioridazine (incidence >3.5%) were haloperidol, propranolol, chlorpromazine, lithium, risperidone and trifluoperazine., Of patients who were prescribed thioridazine from 1997 to 2001, 55.4% to 59.7% were exposed to potential risk of thioridazine related DDIs in the same prescription sheet, 65.2% to 68.9% were exposed to potential risk of thioridazine related DDIs from different prescription sheets. Overall, 75.0% to 77.4% were exposed to potential DDIs with thioridazine.
According to thioridazine prescriptions, the rates of potential thioridazine-related DDIs in the same prescription sheet were 49.2% to 55.2%; and were 51.8% to 55.3% from different prescription sheets. Overall, the rates of potential DDIs with thioridazine were 59.3% to 65.0% per prescription.
We found that polypharmacy is one of the factors that contribute to the high incidence of thioridazine related DDIs. The average daily dose of thioridazine (124.8∼143.2 mg) of the prescriptions with thioridazine related DDIs were lower than that of those without thioridazine related DDIs (150.3∼183.6 mg) (p<0.0001).
Moreover, the average daily dose of thioridazine in combination with potential interactive antipsychotics (120.5∼134.3 mg) were lower than that of thioridazine without such combination (143.7∼178.1 mg) (p<0.0001). The dosage difference is most likely because physicians may prescribe thioridazine with low dose under antipsychotics polypharmacy or the thioridazine was used to as an adjunct treatment to other antipsychotics.
Subjects
藥物交互作用
精神分裂症
健保資料庫
thioridazine
drug interaction
schizophrenia
torsade de pointes
Type
text
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