ABSTRACT
OBJECTIVE: To investigate the effect of capsaicin on the binding rates of simvastatin with rats and healthy subjects plasma. METHODS: The plasma protein binding rates of simvastatin in the presence or absence of capsaicin were determined by ultrafiltration combined with liquid chromatography-mass spectrometry (LC-MS/MS). RESULTS: The binding rates of simvastatin (0.2, 0.5, 1 μg·mL-1) were (97.73±0.24)%, (96.75±2.58)%, and (96.23±0.81)% in rat plasma and (97.05±1.74)%, (97.68±0.65)%, and (97.20±1.00)% in human plasma, respectively. In the presence of capsaicin (1 μg·mL-1), the plasma protein binding rates of simvastatin decreased to (93.97±0.96)%, (92.76±1.89)%, (92.05±0.58)% and (91.71±2.51)%, (91.73±1.88)%, (91.41±2.48)%, while the unbound drug concentration increased by 1.66, 1.23, 1.11 fold and 1.81, 2.56, 2.07 fold, respectively. CONCLUSION: Capsaicin could significantly decrease the plasma protein binding rate of simvastatin and increase its free drug concentration (P<0.01). When the clinical use of simvastatin, attention should be paid to the effect of drugs/ food containing capsaicin on its plasma protein binding rate.