Influence of Obesity and Type 2 Diabetes Mellitus on the Pharmacokinetics of Tramadol After Single Oral Dose Administration

BACKGROUND AND OBJECTIVES: The number of overweight, obese and diabetic patients is constantly increasing. Metabolic disorders may affect the pharmacokinetics of drugs, e.g., by altering the activity of cytochrome P450 (CYP) isoenzymes. Tramadol is a commonly used analgesic metabolised mainly via CYP2D6 to its active metabolite, O-desmethyltramadol. The aim of the study was to assess the influence of overweight, obesity and type 2 diabetes mellitus on tramadol and O-desmethyltramadol pharmacokinetics. METHODS: All patients received a single oral dose (100 mg) of tramadol. The plasma concentrations of tramadol and O-desmethyltramadol were measured with the validated high-performance liquid chromatography method with fluorescence detection. The pharmacokinetic parameters of tramadol and O-desmethyltramadol were calculated by non-compartmental methods. RESULTS: After nephrectomy, the patients were divided into four groups—a control group (n = 12, mean [SD] age 61 [14] years, body mass index (BMI) 22 [2] kg/m(2), CL(cr) (creatinine clearance) 74 [30] mL/min); an overweight group (n = 15, mean [SD] age 63 [11] years, BMI 27 [1] kg/m(2), CL(cr) 81 [35] mL/min); an obese group (n = 12, mean [SD] age 57 [8] years, BMI 33 [4] kg/m(2), CL(cr) 113 [51] mL/min); and an obese and diabetic group (n = 9, mean [SD] age 64 [10] years, BMI 33 [4] kg/m(2), CL(cr) 87 [35] mL/min). Apart from the time to first occurrence of maximal concentration (t(max)), there were no significant differences in the pharmacokinetic parameters of tramadol and O-desmethyltramadol among the groups. Moreover, there were no significant differences in the O-desmethyltramadol/tramadol ratios among the four groups of patients after nephrectomy. CONCLUSIONS: No significant differences were found in the pharmacokinetics of tramadol and O-desmethyltramadol, indicating that the opioid can be administered to overweight, obese and diabetic patients without dosage adjustment.