Use Of Pharm During Pregnancy

Question 1

What are common chronic conditions that should be treated during pregnancy

Answer 1

Allergies and asthma

Diabetes

Epilepsy

HIV

HTN

Mental health conditions

Thyroid disorders

Question 2

What are common acute conditions that need to be treated in pregnancy

Answer 2

Headaches

• primary = NSAIDs and non-pharmacological methods 1st
• secondary = find pathology underlying

UTIs
- MUST always treat to prevent pyelonephritis during pregnancy

STIs
- MUST always treat to prevent transmission to fetus

Question 3

Physiological changes of pregnancy that can influence pharmacotherpaies

Answer 3

Increases in plasma volume, CO and GFR in the 1st and 2nd trimester
- all will influence the level of free drug compared to non-pregnant baseline

Also decreases absorption of drugs that use GI tract
- N/V, delayed gastric emptying and increased gastric pH all work to induce this effect on some medications

Body fat increases

• fat-soluble drugs may have greater volume of distribution and also lowers the plasma concentration fo drugs even more also
• volume (drug) = amount of drug in body (mg)/ Cp (plasma concentration)

Protein binding decreases (decreased serum albumin production
- results in increased free drug concentrations built also increased metabolization and filtered drug (more drug to bind to enzymes/receptors)

Elevated progesterone and estrogen can influence some drug metabolism

Question 4

What is meant by the placenta is “semipermeable”

Answer 4

Generally protects the fetus from most drugs, infections, etc
- this si because the placental has its own unique pharmacokinetic barrier

however transplacental drug transfer can still occur

Factors that influence diffuse of drugs across the placenta
- lipid solubility: more = easily diffusable

• molecular weight: <500 Da readily crosses; 600-1000 Da selectively crosses; >1000 Da nerves crosses (heparin and insulin are the examples for > 1000 Da)
• electrical charge: fetal pH is lower than maternal so weak bases can diffuse easily across the placenta and the protonate and get trapped in fetal blood
• degree of protein binding: fetal circulation has more albumin than maternal = protein bound drugs can accumulate more easily in fetal circulation

Question 5

What are examples of fetal therapeutics

Answer 5

Corticosteroids given to mother for fetal lung maturation in expected preterm birth = increased risk of survival

Antiarrhythmic drugs given to mothers have shown to treat fetal arrhythmias

Maternal use of HIV drugs (3 combo treatment) has been shown to almost completely eliminate fetal infection

Question 6

Teratogenic definition

Answer 6

A substance that:

1) results in a Characteristic set of malformations
2) exerts its effects at a particular stage of fetal development
3) shows a dose-dependent incidence of defect

Continued exposure can produce cumulative effects to multiple organs

• *mechanisms remain poorly understood and are likely multifactorial**
• isotretinoin/etretinate (vitamin A analogs) are believed to influence differentiation process in embroyonic phase
• some medications actually can deplete critical substances/cofactors (I.e valproate acid can cause folic acid Deficency)

Question 7

Common areas affected by teratogens based on fetal week of growth

Answer 7

usually immune weeks 1-2

Weeks 3-5 = eye and heart
- weeks 4-5 = arms and legs

Weeks 6-8 = tether, ears, palate, external genitalia (goes till week 12)

Week 20-38 = brain

** teratogens are more dangerous and cause worse abnormalities during weeks 3 -12 (embryonic period)**

Question 8

Fetal alcohol syndrome

Answer 8

Chronic exposure to ethanol in the womb can result in fetal alcohol spectrum disorder

Severity depends on degree and duration of ethanol exposure (most dangerous and 1st and 2nd trimester)

Symptoms:

• smooth Philtrum and abnormal facial features
• microcephaly
• short stature
• failure to thrive
• hyperactivity
• poor memory and attention
• learning disabilities
• vision and hearing disabilities
• heart/kidney/bone abnormalities

Question 9

Thalidomide

Answer 9

An antiemetic drug that is often used as an example of teratogenic effects intrauterine
- one time injection of this drug between weeks 4-7 causes phocomelia (malformation of limbs)

Question 10

How are drugs assessed for safety during pregnancy?

Answer 10

Quality of evidence is the most important factor

• most desirable evidence = randomized controlled trials (exclude the most bias)
• in order to rank category A = MUST have a controlled trial to establish the link of completely safe

Question 11

What are common preconception planning procedures?

Answer 11

1) patient is taking known teratogenic anti epileptic drug (valproate acid, phenytoin, etc)
- use lowest possible dose of levetiracetam (or if cant use this then absolute lowest dose of drug if cant take off) + add folic acid 4 mg daily

2) patient is taking isotretinoin or other vitamin A analogs
- usually need to remove off this and prevent exposure

3) use of warfarin
- switch to LMWH before becoming pregnant

4) use of alcohol and tobacco
- ideally cease intake before conception or ASAP after conception
- there is no consensus for use of bupropion, transdermal patches, etc for tobacco use

Question 12

What are the two most common teratogenic drugs in breast feeding?

Answer 12

Tetracyclines
- concentration reach 70%and risk permanent tooth staining and bone growth issues

Isoniazid

• gets very high concentration in breast milk and induces seizures due to deficency of vitmain B5
• **need to give pyridoxine supplements for this or stop taking if possible

most medications as long as consulted and taking low dose = safe in breast feeding (some patients will not breast feed due to misconception that all drugs can get to the baby in breast milk)