Sulfapyridine

Sulfapyridine, original UK spelling sulphapyridine, is a sulfonamide antibacterial. At one time it was commonly referred to as M&B.

Sulfapyridine is no longer prescribed for treatment of infections in humans. However, it may be used to treat linear IgA disease. It is a good antibacterial drug, but its water solubility is very pH dependent. Thus there is a risk of crystallization within the bladder or urethra, which could lead to pain or blockage. As with other sulfonamides, there is a significant risk of agranulocytosis, and this, rather than the development of resistance by bacteria, is the main reason for its decline in use.