You will be required to take folic acid and vitamin B12. You will take folic acid, by mouth, daily beginning about 1 week before the first dose of Pemetrexed. You will continue to take it daily until 3 weeks after the last dose of chemotherapy. Vitamin B12 will be given as an injection into your muscle about 1 to 2 weeks before your first dose of Pemetrexed. You will have injections of vitamin B12 about every 9 weeks until 3 weeks after your last dose of chemotherapy.