5-Aminosalicylic acid alone

Substitution of an amino group into the molecule affords an iigent with antibacterial activity. Although seldom used alone, l, ira- aminosalicylic acid (PAS, 7) has been employed as an adjunct Id streptomycin and isoniazid in treatment of tuberculosis. 

The answer is b. (Hardman, p 1061.) Sulfasalazine consists of sul-fapyridine with 5-aminosalicylic acid linked by an azo- bond. This bond is broken by bacteria that release the salicylic acid, which is believed to be the active agent. Sulfa drugs or salicylic acid used alone is not as effective. The mechanism of action is unknown, but it is believed to be protective action on the mucosa by inhibition of the synthesis of prostaglandins and leukotrienes. 

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