✓ 29- Drugs During Pregnancy, Labor and Lactation Flashcards by Hessa Al Salem

What drugs are capable of crossing the placental barrier?

Drugs that are:

Low M.W [< 500 Da]
Non-polar
Non-protein binding

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What effect does heparin administration have on the growing fetus?

No effect as it doesn’t cross the placental barrier

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What effect does insulin administration have on the growing fetus?

No effect as it doesn’t cross the placental barrier

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T/F: concentrations of drugs is much lower in fetal circulation as compared to maternal.

False, majority of drugs reach concentration in the fetus like those in maternal blood

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T/F: Paracetamol is contraindicated throughout the pregnancy and is not used in pregnancy under any circumstances.

False, it’s a category B drug that can be used for fever to prevent any harm it may cause the fetus

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What drugs is used for gestational DM?

Insulin

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Are drugs a common cause of fetal congenital abnormalities?

No, only causes 2-3% of cases

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How can drugs affect the growing fetus?

Directly interacts with fetal tissue
Contracting uterine muscle
Reduced fetal BF ( placental ischemia)

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How can drugs reduce fetal blood glow?

→ Placental vasoconstriction→ Lowers Systemic BP in mother → decreasing fetal BF [indirectly]

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What is the “ All or None” period?

1st week of fertilization/pre-implantation period

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What is the “teratogenesis” period?

Organogenesis period [2-8 week]

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What is the “Organ Dysfunction” period?

Fetal development period [3-9 months]

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What drugs may effect the fetus during the pre-implantation period?

Alchohol
Methotrexate

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What drugs may effect the fetus during the organogenesis period?

Thalidomide
Warfarin
Valproate
Vitamin A derivatives

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What structural deformity is caused by Valproate?

Tall forehead
Cleft lip

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What structural deformity is caused by Thalidomide?

Amelia
Phocomelia

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What structural deformity is caused by Warfarin?

Nasal hypoplasia

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What structural deformity is caused by Vitamin A derivates?

Skeletal deformities

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What drugs may effect the fetus during the fetal development period?

Antithyroid drugs
ACEI
Aminoglycosides
Tetracyclines

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What structural deformity is caused by Antithyroid drugs?

Neonatal hypothyroidism [Goiter]

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What structural deformity is caused by ACEI?

Fetal renal failure

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What structural deformity is caused by Aminoglycosides?

Kidney damage and hearing problem

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What structural deformity is caused by tetracycline

Bone and teeth formation

What drugs given around labor effects the fetus?

Aspirin
NSAIDs
Opiates
Sulfonamides
Benzodiazepines

What effects are seen when Sulfonamides is administered around labor?

* Neonatal Jaundice * Hemolytic anemia

What effects are seen when large doses of Aspirin and NSAIDs are administered around labor?

* Delayed labor * Bleeding * Premature closure of Ductus Arteriosus

What effects are seen when Opiates and Benzodiazepines are administered around labor?

* Respiratory depression * Feeding difficulties * Hypotension

Define Category A drugs

* Remote possibility of fetal harm * Studies show no fetal risk during pregnancy

List examples of Category A drugs

* Vitamin B6 * Thyroid Hormone

Define Category B drugs

No studies on human, but animal studies show no risk

List examples of Category B drugs

* Paracetamol * Penicillins

Define Category C drugs

No studies in humans, and animal studies show some risks. But drugs benefits outweigh potential risk

List some examples of Category C drugs

* Quinolone antibiotics [Ciprofloxacin] * Corticosteroids * Fluconazole

Define Category D drugs

Evidence of human fetal risks, so it shouldn’t be used during pregnancy except if needed for serious disease and no effective alternative

List some examples of Category D drugs

* Phenytoin * Valproic acid * Tetracycline * Aminoglycosides

Define Category X drugs

Studies or experience show fetal abnormalities in both humans and animals, and risks clearly exceed benefits

List some examples of Category X drugs

* Thalidomide * Warfarin * Retinoids

Who cannot use Category X drugs?

Pregnant women or those trying to get pregnant

How does pregnancy affect drug absorption?

Reduced gastric acid secretion and intestinal motility due to increased female hormones Frequent vomiting in early pregnancy

What is the fetal development period?

From 3rd-9th months, at this point drugs modify the function of fetal organs, not their gross appearance

What is the organogenesis period?

A period of teratogenesis, where drugs cause structural deformities. This is from Week 2-8

What is the pre-implantation period?

Fetus may recover or die from the effects of the drug. This period is up until a week of fertilization

How does pregnancy affect drug’s volume of distribution?

* Increase of intravascular and extravascular water content → increased VD for hypophilic drugs * Increase in fat deposition and body weight → increase of VD for fat soluble drugs * _But_ there’s a decreased serum albumin

How does pregnancy affect the metabolism of metoprolol?

CYP2D6 is induced during pregnancy → increased metabolism → decreased efficacy

How does pregnancy affect the metabolism of imipramine?

Estrogen decreases oxidation → increases efficacy

How does pregnancy affect the renal clearance of drugs?

Increases clearances due to increased maternal CO [30%], RBF, and GFR

How does pregnancy affect the clearance of penicillins?

Penicillins, such as amoxicillin, are cleared through renal elimination, and it’s clearance is increased during pregnancy

How does pregnancy affect the hepatic metabolism of drugs?

Hepatic clearance increases due to induction of hepatic enzymes and increased hepatic blood flow

How does pregnancy affect the bile dependent elimination of drugs?

Elevated estrogen causes cholestasis, reducing thus route of elimination and increased efficacy of drugs eliminated through this route

What drugs are used in higher doses in the second and third trimesters and why?

Phenytoin and Valproic acid, as their clearance is increased during pregnancy

What drugs should be avoided in breast feeding?

* Benzodiazepines * Narcotic analgesics * Anti thyroid drugs * Sulfonylureas * Anti cancer drugs [methotrexate]

What drugs suppress lactation?

* Thiazide diuretics * Estrogen [in high doses]

What drugs are safe in breast feeding mothers?

* Penicillins, cephalosporins * Theophylline, salbutamol * Anticonvulsants * Antihypertensives (beta blockers, methyldopa) * Warfarin, heparin * Tricyclic antidepressants

Describe whic drugs achieve higher concentrations in milk?

Unionized, highly lipid soluble, and with low protein binding

How would drugs pass to the baby during breast feeding?

Most drugs are secreted into milk through passive diffusion and reach to suckling babies

What are the guidelines to minimize drug effects during breastfeeding?

* If possible avoid drugs * Use the safest effective medicine * Decrease babies’ exposure via: * Using the lowest possible dose * Taking medications immediately after breast feeding * Alternating breast feeding with bottle feeding