Background: Troglitazone is a CYP3A4 isoenzyme inducer known to decrease the plasma concentration of drugs metabolized by CYP3A4. Atorvastatin, a known substrate of the CYP3A4 pathway, is often used in combination with troglitazone 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 atorvastatin.
Method: We retrospectively reviewed the medical records of patients who received concomitant troglitazone and atorvastatin therapy during a 24-month period. Patients were included in the analysis if during the study period, complete laboratory data were available (fasting lipid profile and glycosylated haemoglobin), the dose of atorvastatin remained unchanged, there were no 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. All of these patients were male, with a mean age of 63. All patients were receiving insulin only for diabetes control when the troglitazone was added. There was an increase in LDL-cholesterol and triglycerides of 23.3% and 21.3%, respectively.
Conclusion: The increase in LDL-cholesterol and triglycerides on atorvastatin and troglitazone combination therapy compared with atorvastatin mono-therapy is suggestive of a drug interaction. Further studies involving troglitazone and atorvastatin may be warranted to substantiate this interaction.