Approved by the FDA in 1980, trimethoprim as a single agent is used only for the treatment of uncomplicated urinary tract infections. The argument for trimethoprim as a single agent was summarized in 1979 by Wormser and Deutsch.118 They point out that several studies comparing trimethoprim with TMP-SMX for the treatment of chronic urinary tract infections found no statistically relevant difference between the two courses of therapy. Furthermore, some patients cannot take sulfonamide products for the reasons discussed previously in this chapter. The concern is that when used as a single agent, bacteria now susceptible to trimethoprim will rapidly develop resistance. In combination with a sulfonamide, however, the bacteria will be less likely to do so. That is, they will not survive long enough to easily develop resistance to both drugs.
Sulfamethoxazole and Trimethoprim
The synergistic action of the combination of these two drugs is discussed previously in this chapter.
Was this article helpful?