Potential interaction between troglitazone and atorvastatin

Background: Troglitazone is a CYP3A4 isoenzyme inducer known to decrease th e plasma concentration of drugs metabolized by CYP3A4. Atorvastatin, a know n substrate of the CYP3A4 pathway, is often used in combination with trogli tazone for diabetic patients with dyslipidemia. Aims: The purpose of this study was to investigate the clinical effects of troglitazone on the fasting lipid profiles of patients receiving atorvastat in. Method: We retrospectively reviewed the medical records of patients who rec eived concomitant troglitazone and atorvastatin therapy during a 24-month p eriod. Patients were included in the analysis if during the study period, c omplete laboratory data were available (fasting lipid profile and glycosyla ted haemoglobin), the dose of atorvastatin remained unchanged, there were n o changes in the diabetic drug regimen, patients received at least 3 months of combination therapy and patients were adherent with their medication. Results: Four out of 31 (13%) patients satisfied the inclusion criteria. Al l of these patients were male, with a mean age of 63. All patients were rec eiving insulin only for diabetes control when the troglitazone was added. T here was an increase in LDL-cholesterol and triglycerides of 23.3% and 21.3 %, respectively. Conclusions: The increase in LDL-cholesterol and triglycerides on atorvasta tin and troglitazone combination therapy compared with atorvastatin mono-th erapy is suggestive of a drug interaction. Further studies involving trogli tazone and atorvastatin may be warranted to substantiate this interaction.