[Lincosamides].

The two main antibiotics that make up the group of lincosamides are lincomycin and its more recent derivative clindamycin; the latter, more active drug is gaining preference over the former. These antibiotics are active primarily against Gram positive cocci (i.e. staphylococci, pneumococci and group A and unclassifiable streptococci) and against most anaerobes (including Bacteroides fragilis). This action originates in binding to the 50S ribosomal fraction. Lincosamides may be given per os, intramuscularly or intravenously. After an oral dose of clindamycin, 90% of the drug is absorbed, and the peak serum level is reached within the first hour. Drug absorption is not modified by meals. Regardless of the route of administration, the serum half life of clindamycin is 2 to 3.8 hours in healthy individuals. Longer half lives are observed in patients with severe renal or hepatic failure, requiring that lower dosages be given by widening the intervals between doses. Diffusion of lincosamides into tissues is of clinical significance except for the central nervous system, especially the cerebrospinal fluid. On the whole, lincosamides are well tolerated. Pseudomembranous colitis is a potential hazard. The main indications of clindamycin are infections due to anaerobes, especially intestinal and vaginal infections. As clindamycin has virtually no effect against Gram negative aerobic pathogens, in most instances another antibiotic, usually an aminoglycoside, is given simultaneously. Other less common indications are some instances of aspiration pneumonia, septicemias due to B. fragilis, and actinomycoses. Because of the risk of pseudomembranous colitis, prophylactic use of clindamycin to prevent postoperative infections following colorectal surgery seems unadvisable.