Box 2. Physiological changes in pregnancy and potential effects on pharmacokinetics (as reviewed in 10).
| Physiological change in
pregnancy |
Potential effect on
pharmacokinetics of drugs |
|---|---|
| ↓ gastric emptying/small
bowel motility |
↑ time to reach peak levels |
| ↑ gastric pH | ↓ absorption |
| ↑ vascularity and oedema
respiratory mucosa |
↑ absorption of inhaled drugs |
| ↑ minute ventilation | ↓ protein binding due to
respiratory alkalosis |
| ↑ total body water, blood
volume and capillary hydrostatic pressure |
↑ volume of distribution of
hydrophilic drugs |
| ↑ glomerular filtration rate | ↑ renal clearance |
| ↓ serum albumin | ↑ active fraction of drug |
| ↑ CYP450 and ↑ UGT activity | ↑ metabolism |