3-16. TOPICAL ANTI-INFECTIVES
a. These agents are used to help prevent or treat infection in minor cuts, burns,
and abrasions. This use occasionally allows the overgrowth of nonsusceptible
organisms, including fungi. Ideally, the topical application of these agents used
systemically should be avoided because of sensitization. Systemic antibiotics are preferred
in deeper, chronic infections.
b. Examples of these agents are:
Povidone-Iodine (Betadine) Ointment.
3-17. THE SULFONAMIDES
a. The compound p aminobenzenesulfonamide, now known as sulfanilamide,
was first synthesized in 1908, but it was not until many years later that its therapeutic
value was known. In 1932, a red dye was prepared; it was later reported to have
remarkable curative effects and was named Prontosil. It was found that the bacterial
property of the drug rested in the p aminobenzenesulfonamide portion of the molecule.
In 1937, sulfapyridine, which was the first sulfonamide used with great success in
treating pneumonia, was synthesized. Since that time, over 3300 sulfonamides have
been prepared, but only a few have been accepted for medical use.
b. The sulfonamides possess a wide antimicrobial spectrum, which include both
gram-positive and gram-negative organisms. These agents compete with
p-aminobenzoic acid and prevent its normal cellular utilization, particularly its
incorporation into folic acid.
c. Most of the sulfonamides are absorbed from the gastrointestinal tract and
distributed throughout the body. They should be taken with large amounts of water.
d. They are metabolized by enzymes in the liver, resulting in a product with no
antimicrobial activity. Both the free drug and its metabolites are excreted through the
e. Dosage of these agents is varied. Oral administration is preferred since
parenteral forms are quite irritating to tissue. Short acting sulfonamides are usually
given at 4 to 5 hour intervals and an initial loading dose is usually recommended.
Longer acting agents are usually given every 8 to 12 hours.