Sulfonamides are competitive inhibitors of the bacterial enzyme Dihydropteroate synthetase.
Sulfonamides are structural analogs and competitive antagonists of para amino benzoic acid (PABA). They inhibit normal bacterial utilization of PABA for the synthesis of folic acid, an important metabolite in DNA synthesis. The effects seen are usually bacteriostatic in nature.
Sulfonamides are not used alone.
It is most often used as part of a synergistic combination with trimethoprim in a 5:1 ratio in co-trimpoxazole. Its primary activity is against susceptible forms of streptococcus, staphylococcus aureus, E.coli, H.influenzae and oral anaerobes.
They can be applied in suppressive therapy of chronic UTI, for streptococcal pharyngitis, gum infection.
Brand Name: Sulfadiazine 0.5 g tab.
Brand Name: Gantantol 0.5g tab
Sulfonamides, Cotrimoxazole
Sulfadoxine, Sulfamethopyrazine
These are ultra long acting compounds, their action lasting to about >1week. They are not suitable for treatment pyogenic infection.
Brand Name: Locula, Albucid 10%, 20 % , 30% eye drops.
Used in the treatment of ulcerative colitis and rheumatoid arthritis.
Brand Name: Sulfamylon 1% cream for surface application. It has been mainly applied to burn dressing to prevent infection. The biggest disadvantage is burning sensation when applied to raw surface.
Used topically as 1% cream. It is used to prevent infection of burnt surface and chronic ulcers.
It is a fixed dose combination of trimethprin and sulfamethoxazole.
Synergistic antibacterial effect when compared to each of its components administered singly. This is because trimethoprim and sulfamethoxazole inhibit successive steps in the folate synthesis pathway.
Similar to sulfonamides.
