Sunitinib-paracetamol sex-divergent pharmacokinetics and tissue distribution drug-drug interaction in mice

The Influence of Paracetamol on the Penetration of Sorafenib and Sorafenib N-Oxide Through the Blood-Brain Barrier in Rats

Background and Objective

Sorafenib is an oral, multikinase inhibitor with established single-agent activity in several tumor types. Sorafenib was moderately transported by P-glycoprotein (P-gp) and more efficiently by breast cancer resistance protein. The constitutive androstane receptor (CAR) is a ligand-activated transcription factor involved in P-gp regulation in the brain microvasculature. Paracetamol is a CAR activator. The purpose of this study was to investigate the effect of paracetamol on the brain uptake of sorafenib and sorafenib N-oxide.

Methods

The rats were assigned to two groups—rats receiving oral paracetamol 100 mg/kg and sorafenib 100 mg/kg (n = 42, I_SR+PA) and rats receiving oral vehicle and sorafenib 100 mg/kg (n = 42, II_SR). The sorafenib and sorafenib N-oxide concentrations in blood plasma and brain tissue were determined by a high-performance liquid chromatography method with ultraviolet detection. Brain-to-plasma partition coefficient (K_p) was calculated as a ratio of the area under the curve from zero to 24 h (AUC) in the brain and plasma. A drug targeting index (DTI) was estimated as the group I_SR+PAK_p to group II_SRK_p ratio.

Results

Pharmacokinetic analysis revealed increased brain exposure to sorafenib and sorafenib N-oxide after co-administration of paracetamol. The brain maximum concentration (C_max) and the AUC of the parent drug in the I_SR+PA group compared with the II_SR group were greater by 49.5 and 77.8%, respectively, and the same parameters for the metabolite were higher by 51.4 and 50.9%. However, the K_p values of sorafenib and sorafenib N-oxide did not differ significantly between the two animal groups and the DTI values were close to 1.

Conclusion

Paracetamol increases exposure to sorafenib and sorafenib N-oxide in the brain, likely due to increased exposure in plasma.

The concomitant use of lapatinib and paracetamol - the risk of interaction

Lapatinib is a tyrosine kinase inhibitor used for the treatment of breast cancer. Paracetamol is an analgesic commonly applied to patients with mild or moderate pain and fever. Cancer patients are polymedicated, which involves high risk of drug interactions during therapy. The aim of the study was to assess the interaction between lapatinib and paracetamol in rats. The rats were divided into three groups of eight animals in each. One group received lapatinib + paracetamol (I_L + PA), another group received lapatinib (II_L), whereas the last group received paracetamol (III_PA). A single dose of lapatinib (100 mg/kg b.w.) and paracetamol (100 mg/kg b.w.) was administered orally. Plasma concentrations of lapatinib, paracetamol and its metabolites – glucuronide and sulphate, were measured with the validated HPLC-MS/MS method and HPLC-UV method, respectively. The pharmacokinetic parameters of both drugs were calculated using non-compartmental methods. The co-administration of lapatinib and paracetamol increased the area under the plasma concentration-time curve (AUC) and the maximum concentration (C_max) of lapatinib by 239.6% (p = 0.0030) and 184% (p = 0.0011), respectively. Lapatinib decreased the paracetamol AUC_0-∞ by 48.8% and C_max by 55.7%. In the I_L + PA group the C_max of paracetamol glucuronide was reduced, whereas the C_max of paracetamol sulphate was higher than in the III_PA group. Paracetamol significantly affected the enhanced plasma exposure of lapatinib. Additionally, lapatinib reduced the concentrations of paracetamol. The co-administration of lapatinib decreased the paracetamol glucuronidation but increased the sulphation. The findings of this study may be of clinical relevance to patients requiring analgesic therapy.

Sex-Divergent Clinical Outcomes and Precision Medicine: An Important New Role for Institutional Review Boards and Research Ethics Committees

The efforts toward individualized medicine have constantly increased in an attempt to improve treatment options. These efforts have led to the development of small molecules which target specific molecular pathways involved in cancer progression. We have reviewed preclinical studies of sunitinib that incorporate sex as a covariate to explore possible sex-based differences in pharmacokinetics and drug–drug interactions (DDI) to attempt a relationship with published clinical outputs. We observed that covariate sex is lacking in most clinical outcome reports and suggest a series of ethic-based proposals to improve research activities and identify relevant different sex outcomes. We propose a deeper integration of preclinical, clinical, and translational research addressing statistical and clinical significance jointly; to embed specific sex-divergent endpoints to evaluate possible gender differences objectively during all stages of research; to pay greater attention to sex-divergent outcomes in polypharmacy scenarios, DDI and bioequivalence studies; the clear reporting of preclinical and clinical findings regarding sex-divergent outcomes; as well as to encourage the active role of scientists and the pharmaceutical industry to foster a new scientific culture through their research programs, practice, and participation in editorial boards and Institutional Ethics Review Boards (IRBs) and Research Ethics Committees (RECs). We establish the IRB/REC as the centerpiece for the implementation of these proposals. We suggest the expansion of its competence to follow up clinical trials to ensure that sex differences are addressed and recognized; to engage in data monitoring committees to improve clinical research cooperation and ethically address those potential clinical outcome differences between male and female patients to analyze their social and clinical implications in research and healthcare policies.