Simultaneous determination of imrecoxib and its two active metabolites in plasma of hepatic impairment patients by liquid chromatography-tandem mass spectrometry

Comparative Pharmacokinetics and Safety of Imrecoxib, a Novel Selective Cyclooxygenase-2 Inhibitor, in Elderly Healthy Subjects

Background

Imrecoxib is a novel and moderately selective cyclooxygenase-2 inhibitor with properties of anti-inflammation and alleviating pain, which is widely applied in osteoarthritis patients. The pharmacokinetic data supporting imrecoxib’s rational use in elderly population are not available.

Purpose

The study aims to investigate the pharmacokinetics of imrecoxib and its main metabolites and explore the safety of imrecoxib in elderly healthy subjects.

Methods

A total of 19 healthy subjects including 10 non-elderly and 9 elderly subjects received single dose of 100 mg imrecoxib under fasting condition. Pharmacokinetics, safety and tolerability profiles were assessed.

Results

After oral administration of single dose of 100 mg imrecoxib, it was absorbed into plasma with median time to reach peak concentration (T_max) around 2 hours. The concentration–time curves of imrecoxib (M0) showed higher interindividual variability in elderly subjects compared with non-elderly subjects. Peak concentration (C_max) of M0, its hydroxyl metabolite M1 and carboxylated metabolite M2 in plasma increased by 39%, 21% and 17%, and area under concentration–time curve from time 0 to time t (AUC_0-t) of M0, M1 and M2 in plasma increased by 34%, 13% and 27%, respectively, in elderly subjects compared with non-elderly subjects. The 90% CIs of geometric mean ratios of C_max, AUC_0-t and AUC_0-∞ of M0, M1 and M2 between the two groups were not located within 80–125%, indicating C_max, AUC_0-t and AUC_0-∞ were not completely equivalent between non-elderly and elderly healthy subjects. However, comparison of pharmacokinetic data of M0, M1 and M2 between the two groups showed no significant difference (P>0.05). Imrecoxib was well tolerated in both non-elderly and elderly healthy subjects, especially with favorable gastrointestinal and cardiovascular safety profiles.

Conclusion

Pharmacokinetic and safety profiles of imrecoxib in elderly healthy subjects indicated that no dose adjustment should be required for elderly population.

Dose investigation of imrecoxib in patients with renal insufficiency based on modelling and simulation

OBJECTIVE

Imrecoxib is a new moderately selective cyclooxygenase-2 (COX-2) inhibitor. A previous study has shown that drug exposure differs significantly in renally impaired patients. We aim to describe the population pharmacokinetics (PPK) of imrecoxib (M0) and its two metabolites (M1, M2) to provide a theoretical basis for investigating imrecoxib doses for renally impaired patients.

METHODS

Using PPK analysis, 24 patients with 257 different plasma concentrations were studied. Of these, 12 had severe renal impairment and 12 had normal renal function. The dose regimen was simulated based on the final model to compare the ratio (Cu,ss/IC50) of the average unbound concentration at steady state (Cu,ss) to the half-maximal inhibitory concentration (IC50) of COX-2.

RESULTS

Imrecoxib and its metabolite concentrations were satisfactorily described by a two-compartment with first-order transit absorption model for imrecoxib and a one-compartment model for its metabolites. Renal function was a significant binary covariate. Scenarios of '75 mg q12h' and '50 mg q8h' in renally impaired patients had similar Cu,ss/IC50 values with a '100 mg q12h' regimen in subjects with normal renal function.

CONCLUSION

A PPK model of imrecoxib and its two metabolites is presented. The renal insufficiency regimen should be reduced to '75 mg q12h' or '50 mg q8h'.