Before any investigator pursues studying drug kinetics in pregnancy, information regarding drug safety of that particular product will be crucial to designing a protocol and subsequently obtaining Institutional Review Boards (IRB) approval. Even though information in product labeling is usually limited, multiple other sources are available that provide comprehensive information that assess reproductive toxicities from drug exposures. For example, the on-line REPRORISK system available from Micromedex, Inc. contains electronic versions of four teratogen information databases: REPROTEXT, REPROTOX (www.reprotox.org), Shepard's Catalog , and TERIS . These periodically updated, scientifically reviewed resources critically evaluate the literature regarding human and animal pregnancy drug exposures. Other sources of information are the more than 20 comprehensive multidisciplinary Teratogen Information Services (TIS) located in the United States and Canada, which provide patient counseling and risk assessments regarding potential teratogenic exposures (www.otispregnancy.org). Many TIS, such as MotherRisk (www.motherisk.org), employ genetic counselors, who are excellent resources for pre- and postconception counseling.
Of the thousands of pharmaceutical products available only a handful are known human teratogens . Largely as a result of the thalidomideinduced birth defects, most people, both patients and clinicians, over-estimate the risk to pregnancy from drug use and perceive it to be quite large [19, 20]. The overall incidence of major malformations in the general population has been estimated at 1-5% . The etiology of most congenital malformations remains uncertain; approximately 20% are caused by genetic factors and chromosomal abnormalities and 10% are caused by environmental factors such as maternal conditions (4%), infections (3%), and chemicals and drugs (approximately 1% or less) . Teratogenicity is only one important aspect of drug use in pregnant women; however, the appropriate dose necessary for anticipated efficacy is critical as well. Sources of information on appropriate dosing in pregnancy are not available.
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