USUAL DOSE. 300 mg daily in a single dose. Because the relapse rate is high, it is essential that the treatment regimen be continued for a sufficient period of time; routinely, this is considered to be 1 year for preventive therapy.
ACTION AND USE. Chloramphenicol was used extensively when first developed because it had no apparent side effects. It inhibits protein synthesis, is easily absorbed from the gastrointestinal tract, and is effective against most grampositive and gram-negative organisms, and against rickettsiae. Chloramphenicol has been recognized as highly toxic with significant hematologic side effects; i.e., bone marrow depression, anemia, and leukopenia. Currently, it is normally used only for treatment of typhoid and other salmonella, rickettsial diseases, and gram-negative bacteremia resistent to other antibiotics. Because of its serious toxic effects, it is reserved for serious infections that are not amenable to treatment with less toxic preparations.
USUAL DOSE. 50 mg/kg/day in divided doses at 6 hour intervals. The oral method is the preferred method of administration although intravenous infusion is acceptable; intramuscular injection is ineffective.
ACTION AND USE. These are the only polymixin complexes still in use. Because of their excessive nephrotoxic nature, the other polymixin complexes have been discarded. Polymixins act by disrupting the cytoplasmic membrane of the cell causing immediate cell death. The polymixins are bactericidal against almost all the gramnegative bacilli; they are not effective against gram-positive bacteria or fungi.
USUAL DOSE. Polymixin B sulfate is available as a parenteral preparation for intravenous or intrathecal administration; it should not be used intramuscularly. The dosage is 15,000 to 25,000 units/kg/day intravenously; 1 to 3 drops of a 0.1 to 0.25 percent solution hourly for the treatment of conjunctivitis. The preparation can also be used as an ophthalmic solution. Polymixin E sulfate (colistin) is available as an oral suspension for the treatment of diarrhea in children given at 5 to 15 mg/kg/day. It is also available as an otic suspension with neomycin and hydrocortisone for the treatment of superficial bacterial infections of the external auditory canal. The dose is 4 drops 3 or 4 times daily.
ACTION AND USE. Spectinomycin was developed with the sole therapeutic indication being the treatment of gonorrhea. It is largely bacteriostatic and quite effective in the treatment of uncomplicated gonorrhea. Its advantage lies primarily in being a single dose therapy and in patients who are allergic to penicillin or have penicillin resistant strains of the causative organism. It is NOT effective in the treatment of syphilis.
USUAL DOSE. An intramuscular dose of 2 g is recommended. In areas of the world where antibiotic resistance is known to exist, the recommended dose is 4 g in a single dose in two injection sites.
ACTION AND USE. Nitrofurantoin is effective against a wide range of gram-positive and gram-negative organisms, protozoa, and fungi. It is rapidly and completely absorbed from the intestine but has little or no systemic effect because it is rapidly excreted through the kidneys. Its usefulness is limited to urinary tract infections where the drug attains concentration in the urine to which most organisms are sensitive. Macrodantin is a preparation of nitrofurantoin where the crystals are of a controlled size.
USUAL DOSE. Nitrofurantoin is used in the treatment of pyelonephritis, pyelitis, and cystitis. Normal dose is 50 to 100 mg 4 times daily; it should be given with meals to increase absorption and minimize gastrointestinal upset. It is contraindicated where significant renal impairment exists.
ACTION AND USE. Although not an antiinfective, phenazopyridine is included here because it is used almost exclusively in urinary tract infections. Phenazopyridine is a urinary tract analgesic indicated for the symptomatic relief of discomforts arising from irritation of the lower 7-13