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Source: Ward KE. Pregnancy and lactation: therapeutic considerations. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861§ionid=146066717. Accessed May 17, 2017.
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Delayed gastric emptying and vomiting may alter drug absorption during pregnancy.
Increased gastric pH may affect absorption of weak acids and bases.
Higher estrogen and progesterone levels may alter liver enzyme activity and increase elimination of some drugs but accumulation of others.
Maternal plasma volume, cardiac output, and glomerular filtration increase by 30–50% during pregnancy, possibly lowering plasma concentration of renally cleared drugs.
Increased body fat may increase volume of distribution of fat-soluble drugs.
Reduced plasma albumin concentrations may increase volume of distribution of highly protein-bound drugs; however, unbound drugs more rapidly cleared by liver and kidneys.
Placenta is organ of exchange between mother and fetus for a number of substances, including drugs.
Drug molecular weights affect drug transfer across placenta:
Molecular weights >500 daltons (D) cross readily.
Molecular weights from 600 to 1000 D cross more slowly.
Molecular weights >1000 D (eg, insulin and heparin) do not cross in significant amounts.
Lipophilic drugs (eg, opiates and antibiotics) cross placenta more easily than water-soluble drugs.
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CLINICAL PRESENTATION
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Pregnancy-influenced issues.
Common during pregnancy:
Hyperemesis gravidarum (severe nausea/vomiting causing weight loss >5% of prepregnancy weight and ketonuria) occurs in 1–3% of pregnant women.
Gestational diabetes mellitus (GDM) more common in African Americans, Native Americans, Asian Americans, Hispanic Americans, and Pacific Islanders.
Hypertension, including:
Gestational hypertension: Pregnancy-induced hypertension without proteinuria.
Preeclampsia: Hypertension with proteinuria.
Eclampsia: Preeclampsia with seizures (medical emergency)
Chronic hypertension: Diagnosed prior to pregnancy with or without overlying preeclampsia.
Venous thromboembolism (VTE), with risk factors in pregnancy of:
Increasing age.
History of thromboembolism.
Hypercoagulable conditions.
Operative vaginal delivery or cesarean section.
Obesity.
Family history of thrombosis.
Acute care issues that may arise in pregnancy.
Chronic illnesses that may occur in pregnancy.
Allergic rhinitis.
Asthma.
Diabetes mellitus.
Epilepsy.
HIV infection.
Hypertension.
Depression.
Labor and delivery.
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Provide preconception interventions to help ensure optimal pregnancy outcomes.
Relieve symptoms associated with pregnancy-influenced medical disorders.
Prevent congenital malformations caused by medication exposure.
Goals for GDM:
Fasting plasma glucose <90–99 mg/dL (5–5.5 mmol/L)
1-hour postprandial plasma glucose concentrations < /= 140 mg/dL (7.8 mmol/L) or less.
2-hour postprandial glucose <120–127 mg/dL (6.7–7 mmol/L)