Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Chapter 9 Drug Therapy During Pregnancy and Breast-Feeding

2Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Drug Therapy During Pregnancy and Breast-Feeding  Shortage of reliable data on toxicity from drug use during pregnancy or breast-feeding

3Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Drug Therapy During Pregnancy  Two-thirds of pregnant women take at least one medication; most take more.  Used to treat pregnancy-related problems: nausea, constipation, and preeclampsia  Chronic disorders: hypertension, diabetes, epilepsy  Infectious diseases or cancer  Drugs of abuse: alcohol, cocaine, heroin

4Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Drug Therapy During Pregnancy  Physiologic changes during pregnancy and their impact on drug disposition and dosing  Third trimester: renal blood flow doubled and renal excretion accelerated  Tone and mobility of bowel decrease Prolonged transit: increase in absorption Prolonged transit: increase in absorption

5Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Drug Therapy During Pregnancy  Placental drug transfer  All drugs can cross placenta.  Some can cross more easily than others.  Adverse reactions during pregnancy  Can adversely affect both pregnant patient and fetus  Some unique effects Heparin causes osteoporosis. Heparin causes osteoporosis. Prostaglandins stimulate uterine contraction. Prostaglandins stimulate uterine contraction. Certain pain relievers used during delivery can depress respiration in the neonate. Certain pain relievers used during delivery can depress respiration in the neonate.

6Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Drug Therapy During Pregnancy: Teratogenesis  teras = a Greek word meaning “monster”  Teratogenesis = literally, “to produce a monster”  Birth defects  Gross malformations Cleft palate, clubfoot, and hydrocephalus Cleft palate, clubfoot, and hydrocephalus  Neurobehavioral and metabolic anomalies

7Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Teratogenesis  Incidence and causes of congenital anomalies  Less than 1% of all birth defects caused by drugs  Identification of teratogens very difficult  As a result, only a few drugs are considered proven teratogens.

8Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Teratogenesis  Minimizing the risk for teratogenesis  Avoid unnecessary drug use (eg, alcohol, cocaine).  50% of pregnancies are unintended: risks for teratogenesis apply to these pregnancies, too.  Responding to teratogen exposure  Identifying details of exposure  Ultrasound scans

9Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Teratogenesis and Stage of Development  Development occurs in three stages.  Conception through week 2  Embryonic period: weeks 3 to 8 Gross malformations produced by teratogens Gross malformations produced by teratogens  Fetal period: week 9 to term Functions disrupted with teratogen exposure Functions disrupted with teratogen exposure

10Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Fig Effects of teratogens at various stages of development of the fetus.

11Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Drug Therapy During Breast-Feeding  Drugs can be excreted in breast milk, and effects can occur in the infant.  How to decrease risk to the infant:  Take drugs immediately after breast-feeding.  Avoid drugs that have a long half-life.  Choose drugs that tend to be excluded from milk and are least likely to affect the infant.  Avoid drugs known to be hazardous.