The study aimed to compare the pharmacokinetics of 2 pemetrexed formulations (Pemgem, Dr. Reddy's Laboratories w.r.t; Alimta, Eli Lilly) in adult chemonaive subjects with adenocarcinoma stage III/IV non-small cell lung cancer. All patients received 500 mg/m pemetrexed (Alimta or Pemgem) as a 10-minute infusion on day 1 of a 21-day cycle. Plasma pemetrexed concentrations were determined on day 1 of cycle 1. Area under the concentration-time curve (AUC ) and the maximum plasma concentration (C ) were estimated using noncompartment analysis and compared between the 2 arms. Forty-eight patients were enrolled in the study, 24 in each arm. Patient demographics were comparable in both arms. Mean AUC for the generic and innovator formulations was 218.2 ± 19.18 and 223.6 ± 34.24 μg·h/mL, respectively, and mean C was 119 ± 13.44 and 113 ± 7.26 μg/mL, respectively. Volume of distribution of pemetrexed was 17.5 and 27.6 L, clearance was 4.2 versus 4.72 L/h, and half-life was 4.3 and 4.83 h in the 2 arms respectively. Both formulations showed comparable response rates (objective response of 45% versus 50% in the Pemgem and Alimta arms, respectively) and similar safety profiles. To conclude, Pemgem showed pharmacokinetic and safety profiles similar to Alimta. Substitution of Alimta with Pemgem will be cost-effective and likely to yield comparable efficacy.
Background: Rituximab is a chimeric IgG1 monoclonal antibody targeting the CD20 surface antigen on normal and neoplastic B cells. Its use in combination with chemotherapy in CD20 positive B cell lymphomas has translated into better progression free and disease free survival making its incorporation, a standard of care in treatment of these lymphomas. However, the benefits of this important molecule may not have been available to a majority of patient in the developing countries but for the emergence of biosimilars in the market. The lack of defined regulatory norms in approving biosimilars for patient care has left some doubts regarding their true efficacy in comparison to the innovator MabThera® (Roche). Although our clinical experience suggests comparable efficacy and safety for the biosimilar, we embarked on a formal pharmacokinetic study of the biosimilar, Reditux®, used in combination with standard CHOP or CHOP like regimen in patients with diffuse large B cell lymphoma planned for chemo-immunotherapy. We present our data on twenty-one prospectively treated patients and compared it with the published data on MabThera®. Methods: This was a prospective, single centre pharmacokinetic study conducted between Nov 2011 and June 2013. Patients diagnosed with DLBCL, and treated with Reditux® in combination with chemotherapy, were enrolled into the study. All patients received six cycles of R-CHOP, wherein they received 375mg/m2 Reditux as a graded infusion of 50mg, 100mg and maximum 200mg during the first, second and third hour respectively on day 1 of first cycle. The chemotherapy consisted of standard CHOP including cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2 and vincristine 1.4 mg/m2 (for a maximum single dose of 2 mg), administered intravenously on day 1 after Rituximab infusion, along with 100 mg oral prednisone for 5 days from first day. Serial blood sampling was done during the first cycle of R-CHOP at pre-dose, immediately post infusion and thereafter at 24, 48, 144 hours post infusion with a last sample collected on day 21. The plasma level of rituximab was determined by ELISA (Life Technologies, USA) with a sensitivity of 50 ng/mL. Rituximab AUC and other pharmacokinetic parameters were calculated from the observed concentrations at each time point using WinNonlin® version 6.3. The peripheral blood B-cell count was done on day 3 and day 21 of chemoimmunotherapy. The absolute B cell percentage was calculated by flow-cytometry using CD45, CD19 and CD20. Influence of covariates on AUC of Reditux was analyzed by linear regression. Results: A total of 21 patients were enrolled into the study including 18 males and 3 females. The median age was 50 years in the Reditux® group (range 24-70). Four patients were above 60. Majority (n=12) had Stage 4 disease. The pharmacokinetic parameters described in the table were comparable with the pharmacokinetic profile of MabThera® from published literature. High inter patient variability in pharmacokinetics was observed (CV=88%). Age and gender did not influence pharmacokinetics of the biosimilar though the numbers are few to derive firm conclusions. The median B cell count on day 3 and day 21 of first cycle was 1.75 ± 0.27 and 5.56 ± 1.24 cells/µl respectively. Of the 21 patients, four were lost to follow up while 2 patients had progressive disease and died. At a median follow of 19 months 70.3% of patients from the Reditux® group were progression free. There was no untoward immediate or late toxicity attributable to Reditux® on follow up. Conclusions: Reditux® has similar pharmacokinetic profile as MabThera®. The B-cell kinetics following Reditux® administration are similar to that reported for MabThera®. This study gives further credence to Reditux® as a suitable alternative to MabThera®in the treatment of CD20 positive B cell lymphomas. Table: Pharmacokinetic parameters of Reditux® and Mabthera® PK parameter (mean ± SD) Reditux®(N=21) MabThera® (published literature) AUC (0-t) hr* µg / mL 54,236 ± 47,555 - C max (µg / mL ) 555.74 ± 141.46 408 Vd ( L) 1.3 ± 0.64 2.7 CL (l/day) 0.15 ± 0.16 0.14 Half life (days ) 10.9 ± 8.6 22 MRT last (days) 2.78 ± 3.08 - Vd=Volume of distribution, CL=Clearance, MRT=Mean Residence Time Disclosures No relevant conflicts of interest to declare.
BackgroundPemetrexed-platinum doublet therapy is a standard treatment for stage IIIb/IV nonsquamous non small cell lung cancer (NSCLC). While the regimen is associated with several grade ≥3 toxicities, hyponatremia is not a commonly reported adverse effect. Here we report an unusually high incidence of grade ≥3 hyponatremia in Indian patients receiving pemetrexed-platinum doublet, and the pharmacological basis for this phenomenon.MethodsForty-six patients with advanced NSCLC were enrolled for a bioequivalence study of two pemetrexed formulations. All patients received the pemetrexed-platinum doublet for six cycles followed by single-agent pemetrexed maintenance until progression. Pharmacokinetic blood samples were collected at predefined time points during the first cycle and the concentration-time profile of pemetrexed was investigated by noncompartmental analysis. Hyponatremic episodes were investigated with serum electrolytes, serum osmolality, urinary sodium, and urine osmolality.ResultsSixteen of 46 patients (35%) had at least one episode of grade ≥3 hyponatremia. Twenty-four episodes of grade ≥3 hyponatremia were observed in 200 cycles of doublet chemotherapy. Plasma exposure to pemetrexed was significantly higher in patients with high-grade hyponatremia than in those with low-grade or no hyponatremia (P=0.063 and P=0.001, respectively). Pemetrexed clearance in high-grade hyponatremia was quite low compared with normal and low-grade hyponatremia (P=0.001 and P=0.055, respectively). Median pemetrexed exposure in this cohort was much higher than that reported in the literature from Western studies.ConclusionHigher exposure to pemetrexed is associated with grade ≥3 hyponatremia. The pharmacogenetic basis for higher exposure to pemetrexed in Indian patients needs further investigation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.