The sulfonamides were the first effective chemotherapeutic agents to be available in safe therapeutic dosage ranges. They were the mainstay of therapy of bacterial infections in humans before the introduction of the penicillins in 1941. All the sulfonamides are synthetically produced and contain the para-amino-benzene sulfanilamide group. The spectrum of activity for all the sulfonamides is similar and all are effective against both gram-positive and gram-negative organisms. They are primarily bacteriostatic and act as an antimetabolite (competitor) to para-aminobenzoic acid (PABA) in susceptible organisms. PABA is required in the formation of folic acid.
Excretion of the sulfonamides is chiefly through the kidneys. Some of the sulfonamides are relatively insoluble in acidic or neutral solutions so there is some danger that a sulfonamide would precipitate out of solution leading to crystal formation, hematuria, or possibly renal shutdown. Forcing fluids to keep the urine dilute or administering alkaline solutions can help to prevent precipitation of sulfonamides. With the newer sulfonamides, this is not a major concern since many of them are soluble in acidic solutions.
Although the sulfonamides have, for the most part, been replaced with other agents, there is still a significant demand in certain types of infection, most notable urinary tract infections, such as acute cystitis or prostatitis, and in cases of acute otitis media. The following lists some of the more common sulfonamides.
ACTION AND USE. This systemic sulfonamide is bacteriostatic and is indicated in the treatment of urinary tract infections and acute otitis media.
USUAL DOSE. 2 to 4 g initially, then 1 to 2 g four times daily for 10 days. The patient should be advised to increase fluid intake. Trimethoprim and
ACTION AND USE. This is an antiinfective combination used in the treatment of urinary tract infections and otitis media. Both drugs are effective antimetabolites but compete at different steps in the formation of PABA. In combination, they are more effective than individually.
USUAL DOSE. Two tablets every 12 hours. The patient should be advised to increase fluid intake.
ACTION AND USE. Sulfacetamide is an ophthalmic bacteriostatic for the treatment of conjunctivitis, corneal ulcer, and other superficial ocular infections. It is available in solutions of various strengths and in an ointment form. Sulfacetamide is inactivated by the paraaminobenzoic acid in purulent exudates.
USUAL DOSE. Solutions of 1 to 2 drops three or four times daily depending on the severity of the infection. The ointment should be applied four times daily.
ACTION AND USE. Silver sulfadiazine is a topical antimicrobial agent used in the treatment of secondand third-degree burns to prevent wound sepsis. [t is water soluble and easily washed off the skin.
USUAL DOSE. Silver sulfadiazine is available in an emollient cream and should be initially applied to a burn wound twice daily in a sterile manner. For each dressing change, the burn wound should be debrided of any dead or sloughing tissues and carefully cleaned to remove any residual purulent exudate.
Penicillin is one of the most important of the antibiotics. It is derived from a number of Penicilliumm molds commonly found on breads and fruit. The mechanisms of action for the penicillins is the inhibition of cell wall synthesis during the reproductive phase of bacterial growth. It is one of the most effective and least toxic of the antimicrobial agents.
Benzylpenicillin (Penicillin G) is the prototype form for all the penicillins. It is highly effective against many of the gram-positive cocci, and, to a lesser extent, the gram-negative cocci. Semisynthetic preparations have been produced to attempt to overcome some of the problems of the naturally occurring penicillins, i.e., instability in an acid medium, rapid renal excretion, susceptibility to penicillinase, and a high incidence of hypersensitivity. Significant differences among the agents