Physicochemical stability of cabazitaxel and docetaxel solutions

Recent progress in nanoformulations of cabazitaxel

The antitumor efficacy of various paclitaxel (PTX) and docetaxel (DTX) formulations in clinical applications is seriously affected by drug resistance. Cabazitaxel, a second-generation taxane, exhibits greater anticancer activity than paclitaxel and docetaxel and has low affinity for the P-glycoprotein (P-gp) efflux pump because of its structure. Therefore, cabazitaxel has the potential to overcome taxane resistance. However, owing to the high systemic toxicity and hydrophobicity of cabazitaxel and the instability of its commercial preparation, Jevtana®, the clinical use of cabazitaxel is restricted to patients with metastatic castration-resistant prostate cancer (mCRPC) who show progression after docetaxel-based chemotherapy. Nanomedicine is expected to overcome the limitations associated with cabazitaxel application and surmount taxane resistance. This review outlines the drug delivery systems of cabazitaxel published in recent years, summarizes the challenges faced in the development of cabazitaxel nanoformulations, and proposes strategies to overcome these challenges.

Significantly Minimizing Drug Wastage and the Cost of Cabazitaxel Used to Treat Metastatic Castration-Resistant Prostate Cancer

Cabazitaxel is used to treat patients with metastatic castration-resistant prostate cancer progressing after docetaxel. It is prepackaged in 60 mg single-dose vials, a quantity much higher than the average prescribed dose, which leads to, substantial drug wastage (DW) and associated costs. To minimize DW we implemented a cost-saving, cohorting strategy where multiple patients scheduled to receive cabazitaxel (at a dose of 20mg/m² every 3 wks) were cohorted and treated on a single weekday whenever possible. Excess drug from each vial was then saved and used for subsequent patients treated on the same day. The drug cost with cohorting was calculated from the actual number of vials used, and the drug cost without cohorting was estimated by assumingthat one vial was used per treatment. The cost of DW was determined based on the amount of drug that was discarded. All cost calculations also accounted for the discount incentives offered by Sanofi-Aventis. Over a 3-yr period, 74 patients received 402 treatments of cabazitaxel. Multiple patients were treated on 67.4% of the treatment days, and grouping of three patients on one day saved one vial. The estimated total drug cost saved was $394 536 CAD (21.1%). Pending further studies on safety and efficacy, this strategy could potentially be adopted to mitigate DW for cabazitaxel and similarly for other oncology drugs. This would significantly decrease the overall financial burden on patients, institutions, and stakeholders. PATIENT SUMMARY: Cabazitaxel chemotherapy is associated with substantial drug wastage and associated costs. By cohorting patients scheduled to receive cabazitaxel on a single weekday, the total drug cost was decreased by $394 536 CAD (21.1%) over a 3-yr period. Similar strategies could be considered to overcome the prohibitory costs associated with drug wastage for cabazitaxel and other cancer drugs.

High concentrated etoposide solutions, additional physical stability data in dextrose 5

OBJECTIVES

According to the manufacturers, the concentration of etoposide solutions should not exceed 0.4 mg/mL due to a risk of precipitation. Stability studies at higher concentrations were conducted and notably demonstrated 28 day stability up to 1.75 mg/mL for etoposide solutions in 5% dextrose (D5W). Nevertheless, colleagues report precipitation even at 0.4 mg/mL in their daily practice. The objective of this work was to reassess the physical stability of highly concentrated etoposide solutions in D5W (1.2 mg/mL), over a large number of preparations and under different manufacturing processes.

METHODS

To study the impact of manufacturing process, etoposide was taken with a spike or a needle and injected in three types of D5W containers (Easyflex, Viaflo and Ecoflac). Forty preparations were made for each container. For half of the preparations, a homogenisation was performed by a syringe rinse. Physical stability was realised by two examiners, with a visual examination searching for the appearance of a precipitate, daily during the first week, then twice a week until day 56.

RESULTS

Hundred and eighteen solutions were clear and colourless. Precipitates were observed for two solutions: one in an Easyflex bag on day 4 and one in an Ecoflac container on day 35.

CONCLUSIONS

The physical stability at 1.2 mg/mL in D5W remains validated. Precipitations are rare and concern less than 2% of preparations. The appearance of a precipitate does not seem to be correlated to the kind of container or manufacturing process. A rinse was performed for these two solutions to assess a mechanical pressure effect more important on the solution, which could lead to a higher risk of precipitations. However, this is not observed in our daily practice, especially at lower concentrated solutions. We only recommend using an administration set with an in-line micro-filter as a precaution in case of precipitations.