In some instances, antimicrobial agents are recommended for specific indications other than indications in the product label (package insert) approved by the US Food and Drug Administration (FDA). The FDA maintains a general Web site (www.fda.gov/cder/orange/default.htm) of approved drug products with therapeutic equivalence evaluations. Another site (www.fda.gov/cder/ob/default.htm) enables searches by active ingredient and proprietary name. An FDA-approved indication means that adequate and well-controlled studies were conducted and then reviewed by the FDA. However, accepted medical practice often includes drug use that is not reflected in approved drug labeling. Lack of approval for an indication does not necessarily mean lack of effectiveness but indicates that the appropriate studies have not been performed or data have not been submitted to the FDA for approval for that indication. Unapproved use does not imply improper use, provided that reasonable medical evidence justifies such use and that use of the drug is deemed in the best interest of the patient. The decision to prescribe a drug resides with the physician, who must weigh risks and benefits of using the drug, regardless of whether the drug has received FDA approval for the specific indication and age of the patient. In addition, occasional drug shortages occur, which require alternative therapy (www.fda.gov/cder/drug/shortages/default.htm) .

Some antimicrobial agents with proven therapeutic benefit in humans are not approved by the FDA for use in pediatric patients or are considered contraindicated in children because of possible toxicity. Some of these drugs, however, such as fluoroquinolones (in people younger than 18 years of age), tetracyclines (in children younger than 8 years of age), and other agents approved for use in adults may be used in special circumstances after careful assessment of risks and benefits. Obtaining informed consent before use is prudent. The following information delineates general principles for use of fluoroquinolones, tetracyclines, and other agents that generally are approved for adults with serious bacterial infections.