Pharmacology treatment during Pregnancy , breastfeeding , neonate Flashcards
Explain changes of pharmacokinetics during pregnancy
Absorption : gastric emptying is delayed for oral preparations ( sitting in stomach for a while might change it’s effect )
Distribution : Total body water and fat are increased = lower concentration of water soluble and lipid soluble drugs AND protein binding is reduced increasing free drug concentration ( active drug )
Metabolism : increased clearance of drugs depending on liver enzyme activity phenytoin and theophylline ( increased liver activity in 3rd trimester )
Elimination : increased renal plasma flow doubles the elimination of renal cleared drugs such as penicillins
Do drugs affect the fetus ? what factors contribute to the degree it effects the fetus at ?
- Most drugs cross the placenta but in variable degrees
- Lipid soluble , water soluble , molecular size, protein binding and metabolism affect crossing
What are the features of a drug that would most easily cross the placenta
Small , lipid soluble , unbound , uncharged molecule crosses most easily
What drugs can effect day 0-16 of gestation
Cytotoxic and Alcohol
What drugs will effect fetal development first trimester ( organogenesis stage ) Day 17-60
Most Teratogens
What drugs will effect fetal development after 60+ days
Alcohol , Nicotine , Radioactive iodine , Corticosteroids
What drugs should be avoided in pregnancy ( Hint : 8 ) , give examples
1- ACEi / ARBs : if patient wants to have a family, not using contraceptive then not prescribed
2- Anticonvulsants ( Phenytoin , valproate, carbamazepine )
3- Antipsychotics ( lithium )
4- Antibiotics ( tetracyclines, trimethoprim , metronidazole )
5- Antithyroid ( iodine , carbimazole, propylthiouracil )
6- Anticoagulant ( warfarin, DOACs )
7- Abuse : alcohol, cigs, opioids,
8- DMARDS / cytotoxics ( methotrexate / cyclophosphamide : reduce high cell turnover
What is used instead of ACEi if patient is trying to get pregnant or is pregnant
Labetolol
What if thyroid problems start during pregnancy
Small amount of carbimazole can be given , not much because can badly effect fetus.
If person with thyroid problem is planning to get pregnant ideally they should wait until thyroid problems are treated first.
When is the administration of drugs at the greatest risk during a pregnancy
In the First Trimester
What is Phocomelia
Phocomelia is the malformation of limbs
What is thalidomide
Thalidomide was used for first trimester vomiting for anti-sickness. This caused Phocomelia in Infants
What is the treatment for nausea and vomiting ( morning sickness ) in pregnancy
1- If mild : nothing or vitamin/electrolyte support
2- 1st line : Promethazine, cyclizing ( antihistamine ) , prochlorperazine & reassess after 24 hours and switch between drugs if not working
3- 2nd line : metoclopamide or ondansetron ( for less than 5 days )
4- 3rd line : Methylprednisolone ( high dose IV corticosteroid ) only in severe cases
What is the treatment of asthma in pregnancy
1- maintain with inhalers
2- Prednisolone if needed
What is the treatment for hypertension in pregnancy
1- Labetolol
2- Nifedipine ( B blocker )
3- Methyldopa
What is the side effect of Methyldopa
works in brain so may change mood of mother
What antibiotics are used during pregnancy for UTI
1- 1ST LINE : Nitrofurantoin
2- 2nd line: Amoxicillin , Cefalexin
What anticoagulation medications are safe during pregnancy
Heparin and LMWH. Avoid Warfarin and DOACs
What anticonvulsants are safe during pregnancy
Seizures are more of a risk than the drug , must consult specialist ( neurologist & OB )
What drugs should be avoided while nursing
1- Diazepam 2- Alcohol 3- Lithium 4- Iodine / propythiouracil 5- Opioids ( if on them mother advised to not breast feed ) 6- Tetracyclines 7- Corticosteroids
How can you give a drug while a mother is Breastfeeding
If drug can affect baby try to give drugs in timing where it doesn’t affect the breast milk
Explain changes in Pharmacokinetics of Baby
Absorption :
1- surface area / bodyweight is greater so absorption of topical agents is increased
2- intramuscular absorption is impaired due to reduced mass
3- rectal absorption is relatively efficient
Distribution:
Body water % is higher so loading dose is greater for drugs based on body weight.
Albumin binding decreased so free concentrations of highly bound drugs increase.
Metabolism:
Impaired oxidation increases concentration of drugs like warfarin, diazepam.
Impaired glucuronidation increases risk of toxicity to drugs metabolized by this mechanism (chloramphenicol )
Elimination :
GFR and reabsorption is impaired so dose reduction needed for renal cleared drugs ( ahminoglycosides, digoxin, penicillin ) . By 6 months renal function is normal and standard doses could be used.
Why can you get neonatal jaundice
If you give highly binding drugs to babies they can displace bilirubin from its protein binding
What is grey baby syndrome
When Chloramphenicol is given to babies
