Drug use in pregnancy and lactation (1)
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Drug use in pregnancy and lactation (1) Drug use in pregnancy and lactation (1) Presentation Transcript

  • Drug Use inPregnancy and lactation (1) By M.H.Farjoo M.D. , Ph.D. Shahid Beheshti University of Medical Science
  • Drug Use in Pregnancy and lactation (1)  Introduction  Principles of Therapy  Physiologic – pharmacokinetics Changes  Maternal – Fetal Circulation  Drug Effects On The Fetus  Drug Categories in Pregnancy  Fetal Therapeutics  Dietary Supplements  Pregnancy-Associated ProblemsM.H.Farjoo
  • Introduction  Drug use during pregnancy and lactation requires special consideration because both the mother and the child are affected.  Few drugs are considered safe, and drug use is generally contraindicated.  Many pregnant or lactating women take drugs for acute or chronic disorders or habitual use of alcohol and tobacco.M.H.Farjoo
  • Principles of Therapy: Pregnancy  Give medications only when clearly indicated, weighing benefits to the mother against the risks to the fetus.  Any drugs used during pregnancy should be given in the lowest effective doses and for the shortest effective time.  The choice of drug should be based on the stage of pregnancy and drug information.M.H.Farjoo
  • Principles of Therapy: Pregnancy (Cont,d)  During the first trimester, an older safe drug is preferred over a newer drug of unknown teratogenicity. Teratogenicity is the ability of a  substance to cause abnormal Counsel pregnant women about the use of fetal development when taken by immunizations during pregnancy. pregnant womenM.H.Farjoo
  • Principles of Therapy: Pregnancy (Cont,d)  Live virus vaccines (measles, mumps, polio, rubella) should be avoided because of possible harmful effects to the fetus.  Inactive virus vaccines (influenza, rabies, hepatitis B) and toxoids (diphtheria, tetanus) are considered safe for use.  Hyperimmune globulins can be given to pregnant women who are exposed to hepatitis B, rabies, tetanus, or varicella.M.H.Farjoo
  • Principles of Therapy: Pregnancy (Cont,d)  Hyperimmune immunoglobulin are IGIVs with high titers of antibodies against viruses or toxins.  Hyperimmune IGIVs are available for hepatitis B virus, rabies, tetanus, and digoxin overdose.  Intravenous administration of the hyperimmune globulins reduces risk or severity of infection.M.H.Farjoo
  • Principles of Therapy: Lactation  Most systemic drugs taken by the mother reach the infant in breast milk.  For some, the amount of drug is too small for others effects are unknown or potentially adverse.  Give medications only when clearly indicated.  For contraindicated drugs, the mother should stop the drug or stop breast feeding.M.H.Farjoo
  • Principles of Therapy: Lactation (Cont,d)  Any drugs used during lactation should be given in the lowest effective dose for the shortest effective time.  Stopping breast feeding during maternal drug therapy is not recommend unless necessary.  In some instances, mothers may pump and discard breast milk while receiving therapeutic drugs, to maintain lactation.  Women with HIV infection should not breast-feed. The virus can be transmitted to the nursing infant.M.H.Farjoo
  • Physiologic – Pharmacokinetics Changes  In the pregnant woman, physiologic changes alter drug pharmacokinetics.  Drug effects are less predictable than in the nonpregnant state.  The physiologic and related pharmacologic changes are as follows:M.H.Farjoo
  • Physiologic – Pharmacokinetics Changes (Cont,d)  Physiologic Change:  50% Increase in plasma volume and body water.  Pharmacokinetic Change:  Water soluble drugs are distributed and “diluted” more than in the nonpregnant state.  Drug dosage requirements may increase.  This effect may be offset by other pharmacokinetic changes of pregnancy.M.H.Farjoo
  • Physiologic – Pharmacokinetics Changes (Cont,d)  Physiologic Change:  Increased weight (~14 Kg) and body fat  Pharmacokinetic Change:  Fat-soluble drugs are distributed more widely.  Drugs distributed to fatty tissues tend to linger in the body because they are slowly released from storage sites.M.H.Farjoo
  • Physiologic – Pharmacokinetics Changes (Cont,d)  Physiologic Change:  Decreased serum albumin.  The rate of albumin production is increased. However, serum levels fall because of plasma volume expansion.  Many plasma protein-binding sites are occupied by hormones that increase during pregnancy.  Pharmacokinetic Change:  More free drug is available for therapeutic or adverse effects on the mother and for placental transfer to the fetus.  A given dose of a drug is likely to produce greater effects than it would in the nonpregnant state.M.H.Farjoo
  • Protein binding Pic.
  • Protein binding Pic.
  • Physiologic – Pharmacokinetics Changes (Cont,d)  Physiologic Change:  Increased renal blood flow and glomerular filtration rate secondary to increased cardiac output.  Pharmacokinetic Change:  Increased excretion of drugs by the kidneys, especially those excreted primarily unchanged in the urine (digoxin, lithium).  In late pregnancy, the increased size of the uterus decreases renal blood flow in supine position.  This results in decreased excretion and prolonged effects of renally excreted drugs.M.H.Farjoo
  • Maternal – Fetal Circulation  On the maternal side, arterial blood pressure carries blood and drugs to the placenta.  Drugs readily cross the placenta, mainly by passive diffusion.  Placental transfer begins approximately the fifth week after conception.  Drugs given on a regular schedule, equilibrate with fetal blood which contains 50% - 100% of the maternal blood.  After entering the fetal circulation, large amounts of drugs are active because albumin levels are low and thus low levels of drug is bound.M.H.Farjoo
  • Maternal – Fetal Circulation (Cont,d)  Drug molecules are distributed in two ways: liver and kidney.  Most are transported to the liver, where they are metabolized.  Metabolism is slow because the fetal liver is immature  Drugs metabolized by the fetal liver are excreted by fetal kidneys into amniotic fluid.  Excretion also is inefficient owing to immature fetal kidneys.  The fetus swallows some amniotic fluid, and some drug molecules are recirculated.M.H.Farjoo
  • Maternal – Fetal Circulation (Cont,d)  Drug molecules are also distributed to the brain.  Drugs enter the brain easily because the blood–brain barrier is poorly developed in the fetus.  Umbilical arteries transport half of the drug- containing blood to the placenta where reenters the maternal circulation.  Thus, the mother can metabolize and excrete some drug molecules for the fetus.M.H.Farjoo
  • Drug Effects On The Fetus  The fetus which is exposed to any drugs circulating in maternal blood, is very sensitive to drug effects  Drugs may cause teratogenicity or other adverse effects.  Drug teratogenicity most likely occurs during the first trimester, when fetal organs are formed.  During the 2nd and 3rd trimesters, drug adverse effects are: growth retardation, respiratory problems, infection, or bleeding.M.H.Farjoo
  • Drug Effects On The Fetus (Cont,d)  Overall, effects are determined mainly by:  The type and amount of drugs  The duration of exposure  The level of fetal growth and development when exposed to the drugs.  Both therapeutic and nontherapeutic drugs may affect the fetus.M.H.Farjoo
  • Drug Categories in Pregnancy  Category A:  Adequate studies in human demonstrate no risk.  Category B:  Animal studies indicate no risk, but there are no adequate studies in human.  Animal studies show adverse effects, but adequate studies in human have not demonstrated a risk.M.H.Farjoo
  • Drug Categories in Pregnancy (Cont,d)  Category C:  A potential risk, when:  Animal studies have not been performed or,  Animal studies indicated no adverse effects and,  There are no data from human studies.  These drugs may be used when potential benefits outweigh the potential risks.M.H.Farjoo
  • Drug Categories in Pregnancy (Cont,d)  Category D:  There is evidence of human fetal risk, but the potential benefits to the mother may be acceptable.  Category X:  Studies in animals or humans or adverse reaction reports or both have demonstrated fetal abnormalities.  The risk of use in a pregnant woman clearly outweighs any possible benefit.M.H.Farjoo
  • Fetal Therapeutics  A few drugs are given to the mother for their therapeutic effects on the fetus, They include:  Digoxin for fetal tachycardia or heart failure  Levothyroxine for hypothyroidism  Penicillin for exposure to maternal syphilis  Prenatal Betamethasone to promote surfactant production in preterm infants.M.H.Farjoo
  • Dietary Supplements  Pregnancy increases nutritional needs and vitamin and mineral supplements are commonly used.  Folic acid supplementation is especially important, to prevent neural tube birth defects (spina bifida).  Such defects occur early in pregnancy, often before the woman realizes she is pregnant.M.H.Farjoo
  • Dietary Supplements (Cont,d)  It is recommended that all women of childbearing potential ingest at least 400 mcg daily from food and/ or a supplement.  In addition, pregnancy increases folic acid needs by 5 to 10 fold and deficiencies are common.  A supplement is usually needed to supply adequate amounts.  For deficiency states, 1 mg or more daily may be needed.M.H.Farjoo
  • Pregnancy-Associated Problems  Anemia  Constipation  Gastroesophageal Reflux  Gestational Diabetes  Nausea & Vomiting  Pregnancy-Induced HypertensionM.H.Farjoo
  • Anemia  Three types of anemia are common during pregnancy:  Physiologic Results from expanded  Iron- deficiency blood volume • Iron preparations should be given  Megaloblastic with food to decrease gastric irritation. Caused by folic acid deficiency • Citrus juices enhance absorptionM.H.Farjoo
  • Constipation  Constipation occurs from decreased peristalsis.  Preferred treatment, if effective, is to increase exercise and intake of fluids and high-fiber foods.  If a laxative is required, a bulk forming agent is the most physiologic because it is not absorbed.  A stool softener or an occasional saline laxative (milk of magnesia) may also be used.M.H.Farjoo
  • Constipation (Cont,d)  Mineral oil should be avoided because it interferes with absorption of fat-soluble vitamins.  Reduced absorption of vitamin K can lead to bleeding in newborns.  Castor oil should be avoided because it can cause uterine contractions.  Strong laxatives or any laxative used in excess may initiate uterine contractions and labor.M.H.Farjoo
  • Gastroesophageal Reflux  Often occurs in the later months of pregnancy.  Nonpharmacologic interventions (eating small meals; avoiding gas producing food and drinks) are recommended.  Antacids may be used if necessary. Because little systemic absorption occurs.  Cimetidine, ranitidine, or sucralfate may also be used.M.H.Farjoo
  • Gestational Diabetes  Some women first show signs of diabetes during pregnancy. This is called gestational diabetes.  Women without risk factors, or whose initial test was normal, should be tested between 24 and 28 weeks of gestation.  Initial management includes nutrition and exercise interventions and calorie restriction for obese women.  If drug is necessary, recombinant human insulin is needed to keep blood sugar levels as nearly normal as possible.M.H.Farjoo
  • Gestational Diabetes (Cont,d)  Oral antidiabetic drugs are generally contraindicated, although acarbose, metformin, and miglitol are almost safe.  These women may revert to a nondiabetic state when pregnancy ends.  They are at increased risk for development of overt diabetes within 5 to 10 years.  Gestational diabetes usually subsides within 6 weeks after delivery.M.H.Farjoo
  • Nausea & Vomiting  Dietary management and maintaining fluid and electrolyte balance are recommended.  Antiemetic drugs should be given only if nausea and vomiting are severe enough to threaten the mother’s nutritional status.  Dimenhydrinate, 50 mg every 3 to 4 hours, are thought to have low teratogenic risks.  Pyridoxine (vitamin B6) also may be helpful 10 to 25 mg daily.M.H.Farjoo
  • Pregnancy-Induced Hypertension  Pregnancy-induced hypertension includes preeclampsia and eclampsia.  They endanger the lives of mother and fetus.  Preeclampsia occurs during the last 10 weeks of pregnancy, during labor, or within the first 48 hr after delivery.  It is manifested by edema, hypertension, and proteinuria.M.H.Farjoo
  • Pregnancy-Induced Hypertension (Cont,d)  Drug therapy includes IV hydralazine or labetalol for blood pressure and magnesium sulfate for seizures.  Eclampsia, occurs if preeclampsia is not treated effectively.  Delivery of the fetus is the only known cure for preeclampsia or eclampsia.M.H.Farjoo
  • Thank you Any question?