Antibiotic, Antifungal, Antiviral Drugs

Systemic use of polymyxin B has, in most cases, been replaced by more effective and less toxic antibiotics for infections caused by susceptible organisms. However, polymyxin B may be useful in infections caused by organisms resistant to these drugs.

Colistimethate sodium is used in the treatment of acute or chronic infections caused by susceptible strains of certain gram-negative bacteria (e.g., Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa).

Lincomycin should be not used for the treatment of minor bacterial infections or for nonbacterial infections. Because of poor CNS penetration, lincomycin should not be used in the treatment of meningitis.

Adverse GI effects frequently occur with oral, IM, or IV lincomycin and may be severe enough to necessitate discontinuance of the drug. Adverse GI effects of lincomycin include nausea, vomiting, diarrhea, abdominal pain, tenesmus, glossitis, stomatitis, and pruritus ani.

The drug also is active in vitro against Arcanobacterium haemolyticum (formerly Corynebacterium haemolyticum). Clindamycin is active against some anaerobic and microaerophilic gram-negative and gram-positive organisms including Actinomyces, Bacteroides, Eubacterium, Fusobacterium, Propionibacterium, microaerophilic streptococci, Peptococcus, Peptostreptococcus, and Veillonella. Clindamycin is active in vitro against Prevotella and Porphyromonas (both formerly classified as Bacteroides); Mobiluncus (motile, anaerobic, curved rods) also are inhibited in vitro by the drug. Clostridium perfringens, C. tetani, Corynebacterium diphtheriae, and Mycoplasma are also inhibited by clindamycin.

Adverse GI effects frequently occur with oral, IM, or IV clindamycin and may be severe enough to necessitate discontinuance of the drug. Adverse GI effects of clindamycin include nausea, vomiting, diarrhea, abdominal pain, and tenesmus.

Clindamycin hydrochloride and clindamycin palmitate hydrochloride are administered orally. Clindamycin phosphate is administered by IM injection or by intermittent or continuous IV infusion. Clindamycin hydrochloride capsules and clindamycin palmitate hydrochloride oral solution can be administered without regard to food. To avoid the possibility of esophageal irritation, clindamycin hydrochloride capsules should be administered orally with a full glass of water.

Clindamycin generally is used for the treatment of serious infections caused by susceptible gram-positive bacteria and for the treatment of serious infections caused by susceptible anaerobic bacteria. Because the risk of severe, potentially fatal Clostridium difficile-associated diarrhea and colitis may be higher with clindamycin than with certain other anti-infectives, use of the drug should be limited to serious infections for which less toxic and/or more effective anti-infectives are not readily available. However, it should be noted that C. difficile diarrhea and colitis has been associated with the use of nearly all anti-infectives, being reported most frequently with clindamycin, cephalosporins, and ampicillin; second and third generation cephalosporins play an increasingly important role.

Limited information is available on the acute toxicity of vancomycin. The IV LD50 of the drug in rats or mice is 319 or 400 mg/kg, respectively. Treatment of vancomycin overdosage is mainly supportive with maintenance of glomerular filtration.

Ototoxicity and nephrotoxicity are the most serious adverse effects of parenteral vancomycin therapy. To date, these adverse effects have not been reported in patients receiving vancomycin orally. The incidences of ototoxicity and nephrotoxicity have not been well established, but clinical experience to date suggests that these adverse effects occur relatively infrequently.