Therapeutics considerations in pregnant and lactating animals Flashcards
What are the key considerations when administering drugs to pregnant animals?
Effect on pregnancy – Can drug disrupt gestation?
Effect on fetus – Risk of teratogenesis or developmental issues
Effect at birth – Can drug cause complications during parturition?
Label indication – Is drug licensed for use in pregnancy?
Risk-benefit balance – Weigh maternal treatment needs vs. fetal harm
Why is it difficult to predict plasma drug levels in pregnancy?
Absorption: Reduced abdominal space, increased gastric pH
Distribution: Increased plasma volume; high Vd drugs cross placenta more
Metabolism: Altered due to increased detoxification needs
Excretion: Changes in dam’s acid-base balance affect drug clearance
What determines if a drug crosses the placenta?
If drug is orally absorbed, it likely crosses placenta
Lipophilic drugs cross more easily
Basic drugs can be trapped in fetal compartment (ion trapping)
How should drug safety be checked before use in pregnancy?
Check data sheet
Consult the company if unclear
Consider risk-benefit analysis
If off-label use is necessary, obtain written owner consent
What are the key concerns when administering drugs during lactation?
Effect on neonate – Can drug be toxic via milk?
Effect on lactation – Can drug reduce milk production?
Drug licensing – Is drug approved for use during lactation?
Milk withdrawal times – Important for food-producing animals
New route of elimination
Metabolic status of dam
Lactation introduces new route of drug elimination, which pharmacokinetic properties influence drug transfer into milk?
Lipid-soluble drugs
Basic, non-ionised drugs
Low plasma protein-binding drugs – More free drug available for transfer
Some drugs are inactivated by milk
How can mastitis during lactation influence drug elimination?
Alters milk pH & mammary blood flow, potentially increasing drug excretion
