Pharmacokinetics
Changes begin in first trimester and peak in second
Absorption
- N/V and delayed gastric emptying
- Increased in gastric pH
Distribution
- Increase in maternal plasma volume
- ↑ fat: ↑ Vd of fat soluble medications
- ↓ Albumin: ↑ Vd of highly bound drugs
Metabolism
- Estrogen and progesterone alter liver enzyme activity (increase or decrease elimination)
Elimination
- ↑ GFR by up to 50%
- Unbound drugs more rapidly cleared by kidney and liver
- Estrogen causes cholestasis - slowed clearance of drugs