[Safety of pemetrexed according to the duration of vitamin B12 and folic acid supplementation prior to the first dose of pemetrexed].

OBJECTIVE

Administration of vitamin B12 and folic acid for 7 days prior to the administration of the first dose of pemetrexed is recommended. However, vitamin supplementation rarely is initiated less than 7 days prior to the first dose of pemetrexed. Therefore, we analyzed the safety of pemetrexed with vitamin supplementation for less than 7 days prior to the first dose of pemetrexed.

METHODS

Patients were classified into 2 groups according to the duration of vitamin supplementation prior to the first dose of pemetrexed: group A received vitamin supplementation for 7 days or more, and group B received vitamin supplementation for less than 7 days. We analyzed adverse effects, such as myelosuppression, rash, and diarrhea, after 1 cycle of pemetrexed therapy.

RESULTS

A total of 70 patients were administered pemetrexed; 40 patients were men and 30 were women with a median age of 64.5 years(range, 43-86 years). A total of 57 patients were classified into group A and 13 into group B; 33 patients were administered pemetrexed as a first-line treatment. Neutropenia of Grade 3 or more was observed in 4/49(8.2%)patients in group A and 2/13(15.4%)patients in group B(p=0.60). There were no significant differences in the rates of occurrence of neutropenia, rash, and diarrhea.

CONCLUSION

This retrospective study indicated that patients could be safely treated with pemetrexed if vitamin supplementation is initiated for less than 7 days prior to the first administration of pemetrexed. However, further studies are needed because of a lack of statistical power and adjustment for confounding factors.