Teratogens ✅ Flashcards
What are teratogens?
Substances producing disruption of embryogenesis by either deformity or malformation
What kind of agents can be teratogens?
- Chemical
- Physical
- Infectious
What does the pattern of abnormality caused by teratogens depend on?
- Timing and magnitude of exposure
- Maternal metabolism
- Placental transfer
- Genetic susceptibility of the embryo
Give 4 categories of chemical teratogenic agents
- Drugs
- Hormones
- Alcohol
- Environment chemicals
Give an example of a teratogenic environmental chemical
Organic mercury
What is the teratogenic effect of organic mercury
Neurological damage resembling cerebral palsy
Give an example of a teratogenic physical agent
High levels of ionising radiation
What can high levels of ionising radiation during pregnancy cause?
- Microcephaly
- Spina bifida
- Cleft palate
- Limb defects
Other than teratogenic effects, what else can high levels of ionising radiation during pregnancy cause?
- Carcinogenic effects
- Mutagenic effects
What is meant by mutagenic effects?
Changes to DNA which can be passed to future generations
Give 8 types of pharmacological agent that may affect a developing foetus?
- Hormones
- Anti-psychotics
- Anti-convulsants
- Anti-microbials
- Anti-coagulants
- Anti-thyroid
- Vitamin A analogues
- Folic acid inhibits
Give 2 hormones that may affect the foetus?
- Progesterone
- Diethylstilbestrol
What is the teratogenic effect of exogenous progesterone
VACTERL
What is the teratogenic effect of diethylstilbestrol?
Vaginal or clear cell carcinoma
Give 2 anti-psychotics that can be teratogenic
- Lithium
- Thalidomide
What is the teratogenic effect of lithium?
Ebstein anomaly
What are the teratogenic effects of thalidomide?
- Short limbs (phocomelia)
- Absent auricles
- Deafness
Give 3 anti-convulsants that can have teratogenic effects
- Sodium valproate
- Phenytoin
- Carbamazepine
What is the clinical presentation of the teratogenic effects of anti-psychotics known as?
Fetal valproate/hydantoin/carbamazpeine syndrome
What are the clinical features of fetal valproate/hydantoin/carbamazepine syndrome?
- Craniofacial, cardiac, and limb defects
- Developmental delay
Give 2 anti-microbials that can have teratogenic effects
- Tetracycline
- Streptomycin
What are the teratogenic effects of tetracycline?
- Tooth enamel hypoplasia
- Yellow staining of teeth
What are the teratogenic effects of streptomycin?
Sensorineural deafness
What anticoagulant can have teratogenic effects?
Warfarin
What is the clinical presentation of the teratogenic effects of warfarin termed?
Fetal warfarin syndrome
What are the features of fetal warfarin syndrome?
- Nasal hypoplasia
- Microcephaly
- Optic atrophy
- Hydrocephalus
- Congenital heart defects
- Stippled epiphyses
- Purpuric rash
Give 2 anti-thyroid medications that can have teratogenic effects?
- Iodine
- Propylthiouracil
What are the teratogenic effects of iodine and propylthiouracil?
- Goitre
- Hypothyroidism
Give a vitamin A analogue that can have teratogenic effects?
Isotretinoin
What are the teratogenic effects of isotretinoin?
- Craniofacial anomalies
- Conotruncal cardiac defects
Give a folic acid inhibitor that can have teratogenic effects?
Methotrexate
What are the teratogenic effects of methotrexate?
- Microcephaly
- Neural tube defects
- Short limbs
How do drugs cause teratogenicity?
Either by interfering directly with embryogenesis or by exerting their pharmacological actions on fetal organs
What is the difficulty of identifying which drugs are teratogenic?
- Adverse effects of medicines difficult to recognise unless they produce recognisable patterns of malformation
- May be considerable delay before teratogenic effects are associated with certain drug
- Presentation of teratogenic effect may be delayed
