Trimethoprim is a synthetic derivative of trimethoxybenzyl-pyrimidine with bacteriostatic and antiprotozoal properties. As a dihydrofolate reductase inhibitor, trimethoprim binds tightly to the bacterial enzyme, blocking the production of tetrahydrofolic acid from dihydrofolic acid, arresting folic acid synthesis._x000D_ When Trimethroprim is combined with sulfonamides, like sulfamethoxazole (S045), the two compounds show bactericidal effects, but are only bacteriostatic when used separately. The activity is attributed to their synergistic effect in inhibiting folic acid metabolism in bacteria. _x000D_ Trimethoprim has a wide antibacterial spectrum and is active against most gram-positive and gram-negative aerobic bacteria, including Nocardia, Brucella, Gram-negative bacilli, and some Gram-positive bacteria like Streptococcus, Toxoplasma and some other coccidians. It is used to treat recurrent cystitis, mild acute prostatitis, urinary tract infections, asymptomatic bacteriuria during pregnancy and respiratory tract infections._x000D_ TOKU-E offers two forms of trimethoprim: Trimethoprim (T011) and Trimethoprim Lactate (T012). Trimethoprim has low solubility in aqueous solution (0.4 mg/mL). Trimethoprim lactate is freely soluble in aqueous solution (19.6 mg/mL).