Antibioticos En Pediatria, Inglés

Antibac terial Agents in Pe diatric s
Susana Chavez-Bueno, MDa,Terrence L. Stull, MDb,*
KEYWORDS  Antibiotics  Antimicrobials  Antibacterials  Pediatrics  Children  Pharmacokinetics

Antibiotics are the therapeutic agents most frequently used in pediatrics. The majority of prescriptions for antibacterial drugs are to treat common pediatric infections such as otitis media, pharyngitis,pneumonia, and other respiratory infections that are diagnosed primarily in the ambulatory setting.1 In many of these cases, however, antimicrobials are inappropriately prescribed; thus, antibiotic overuse is a persistent problem, especially in outpatient pediatric practices.2 Antibiotics are also widely used to treat infections of the skin and soft tissues, genitourinary tract, bones and joints,central nervous system (CNS), and other sites in patients who require hospitalization. Despite their widespread use in pediatrics, few antibiotics have been studied adequately to be considered safe and effective for use in children. Unfortunately, data regarding antibiotic pharmacokinetics, efficacy, and side effects are often extrapolated from studies performed in adults or animals when selectingdosing regimens for children. The US Food and Drug Administration (FDA) addressed the issue with the Pediatric Rule, which became effective in 1999. Under this rule, any application for approval of a human drug or biologic agent is expected to contain data assessing the safety and effectiveness in pediatric patients. Two recent laws, which were reauthorized in 2007, the Best Pharmaceuticals forChildren Act and the Pediatric Research Equity Act, further encourage the research and development of drugs in children. When using antibiotics in children, many factors that are different from those for adults should be considered. A discussion of the general principles of pharmacokinetics and pharmacodynamics pertinent to the pediatric population is included in this article, followed by adiscussion of selected antibiotics that are most commonly used in pediatrics.

Department of Pediatrics, Section of Pediatric Infectious Diseases, University of Oklahoma Health Sciences Center, 940 NE 13th Street, Room 2B 2311, Oklahoma City, OK 73104, USA b Department of Pediatrics, University of Oklahoma Health Sciences Center, 940 NE 13th Street, Room 2B 2308, Oklahoma City, OK 73104, USA *Corresponding author. E-mail address: terrence-stull@ouhsc.edu (T.L. Stull). Infect Dis Clin N Am 23 (2009) 865–880 doi:10.1016/j.idc.2009.06.011 0891-5520/09/$ – see front matter ª 2009 Elsevier Inc. All rights reserved. id.theclinics.com

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PHARMACOKINETICS

Antibiotic pharmacokinetics describe their absorption, metabolism, elimination, and distribution. Gestationaland chronologic age are factors to consider when administering antibiotics to children because various organs mature at different rates as children grow, affecting the pharmacokinetics.3 Other factors affecting pharmacokinetics include underlying diseases, drug interactions, and tissue distribution. Parenteral antibiotic administration often results in higher and more predictable serumconcentrations compared with the oral route. Oral bioavailability of most beta-lactam antibiotics, for example, is approximately 5% to 10% compared with the intravenous (IV) route. However, certain antibiotics, including clindamycin, trimethoprim/sulfamethoxazole, and linezolid, on the other hand, have excellent bioavailability after administration by the oral route, and the serum concentrations are similarto those found after an IV dose. Hepatic function changes over time as the result of variations in blood flow and the maturation of enzyme systems. In neonates, both phase I (primarily oxidation) and phase II enzymes (conjugation) may be reduced, although they are more active by 2 months of age.4 After the first year of life, the levels of most liver enzymes are similar to the levels in...