knowledge about drug therapy during pregnancy is essential to prescribe during pregnancy

1. DRUG THERAPY IN PREGNANCY
Developed By
DR.MOUTUSI DATTA (MBBS,MD)
MEDICAL OFFICER - GRADE IV THS

2. INTRODUCTION
 Treatment options are limited
 Maternal ailment - direct impact on fetus
 Drug therapy in pregnancy is a situation
of complex decisiveness

3. TRAGEDY OF THALIDOMIDE
o Tragedy in early 1960 is a landmark in drug history
o Safe & effective hypnotic and antiemetic
o Potent teratogen - phocomelia
o Thalidomide disaster led to the establishment
of drug regulatory mechanism

5. EFFECTS OF DRUGS ON THE EMBRYO, FETUS, OR NEONATE
o May vary -
o No effect
o Little
o Serious - fetal toxicity
o Spontaneous abortion
o Death
o Fetal malformations.

6. PATHOPHYSIOLOGICAL BASIS OF DRUGS AFFECTING FETUS
 Directly teratogenic
 Placental function alteration
 Changing myometrial activity
 Altered biochemical & functional dynamics

7. FETAL EFFECTS FROM DRUGS DEPEND ON
Time - when drug is taken in pregnancy.
< 3 weeks : all or none effect
3 - 8 weeks : true teratogenecity , covert embryopathy
9th week to term : altered growth , biochemical &
physiological functions

8. Vulnerability of unborn child

11. PHARMACOKINETICS OF DRUGS DURING PREGNANCY
 Absorption - decreased GI motility causes increased drug absorption.
 Intramuscular absorption of drug is more rapid due to increased blood flow
 Distribution - protein binding is decreased
 Causes increased free drug to be available.
 Plasma and extracellular fluid volume expands
 Increased volume of drug distribution

12. PHARMACOKINETICS
•Metabolism : Increased
• hepatic microsomal enzymes undergo induction
•Excretion :
• In the 3rd trimester increased renal blood flow & GFR causes
some drugs to clear the body faster.

13. PLACENTAL DRUG TRANSFER
o The placenta is not a complete barrier:
o Some drugs are stopped
o Some drugs(in fact most) are not
o Ways drugs are transfered across:
o Simple diffusion
o Active transport

14. TRANSFER DEPENDS ON SEVERAL FACTORS
o Physiochemical property of the drug
o pH difference
o Molecular weight
o Protein binding capabilities
o Lipid solubility
o Period of time drug remains in maternal bloodstream
o Half life

15. Characteristics of molecules that crosses
placental barrier

16. TRANSFER DEPENDS ON SEVERAL FACTORS
• Pathological processes of the placenta
• Gestational age (3rd
Trimester): Increased blood flow
to the placenta
• Decreased thickness
• Increased surface area

18. TERATOGENECITY
• Terato - ‘monster’ ; Gen –’producing’
• Six major teratogenic mechanism :
• Folate mechanism alteration
• Neural crest cell disruption
• Endocrine disruption
• Oxidative stress
• Vascular disruption
• Specific receptor or enzyme mediated

19. FDA SYSTEM OF DRUG CATEGORIES IN PREGNANCY

20. WHY TERATOGENIC AGENTS SOMETIMES
DIFFICULT TO IDENTIFY?

21. o INCIDENCE OF CONGENITAL ANOMALIES IS GENERALLY LOW
o Animal Tests May Not Be Reliable
o Prolonged Or Increased Exposure Maybe Required
o Effects Maybe Delayed Or Not Recognized
o Behavioral Effects Are Difficult To Document
o Controlled Experiments Cannot Be Done On Humans

22. • Documentation is incomplete
• Only in a limited number of drugs is the teratogenic
effects known or proven.
• Lack of proof of teratogenicity does not mean a drug is
safe in pregnancy
• May mean there is a lack of research or information.

23. DRUG THERAPY DURING PREGNACY
• Centered on risk/benefit ratio
• Effects of some medication are known
• Unknown-
• New medications
• Different combinations
No drug is absolutely safe

24. RECENT STUDIES
• 75% of pregnant patients use 3-10 different
drugs(prescription or OTC) during their pregnancy
• OTC drugs were used 4 times that of prescription drugs

25. TYPES OF DRUGS USED COMMONLY BY
PREGNANT PATIENTS
• Dietary supplements
• Antiemetics
• Antacids
• Sedatives
• Hypnotics
• Antibiotics
• Antihistamines
• Analgesics
• Tobacco
• ETOH

26. PROVING A DRUG AS A TERATOGEN
3 criteria must be met:
1. Drug must cause a characteristic set of malformations
2. It must act during a specific window of vulnerability i.e.
3-8 weeks of gestation
3. The incidence of malformations should increase with
increased dosage & duration of exposure

27. SAFER MODE OF PRESCRIBING IN PREGNANCY
• Do not start any medication unless clearly indicated
• Do not discontinue medicines that successfully
maintain the maternal condition
• Ask about and document non- prescription medications

28. Safer mode of prescribing in pregnancy
• Have a pregnancy medication reference available
• Use older medicines with longer record of use
• Report adverse outcomes

29. Pharmacotherapeutic decision making during pregnancy

30. EDUCATION OF PREGNANT PATIENTS
• Provide accurate information with rationales
• Information sould be current and based on evidence
• Establish environment conducive to exchange of
information – trust
• Explain potential harm / risks

31. SELF TREATMENT WITH DRUGS DURING PREGNANCY
SELF TREATMENT OF ANY ILLNESSES SHOULD BE DISCOURAGED
WOMEN SHOULD BE INSTRUCTED TO KEEP A COMPLETE RECORD OF
ALL MEDICATIONS TAKEN

32. Examples of known teratogens

33. Thank you