TY - JOUR T1 - Changes in drug handling during pregnancy: what it might mean for your patients. JF - Canadian Family Physician JO - Can Fam Physician SP - 1214 LP - 1215 VL - 52 IS - 10 AU - Gideon Koren Y1 - 2006/10/01 UR - http://www.cfp.ca/content/52/10/1214.abstract N2 - QUESTION: A pregnant patient taking lithium for bipolar depression is clinically uncontrolled despite a high dose. She insists that she is taking the medication. Her lithium serum levels have fallen from 1 mEq/L to 0.6 mEq/L. What is the reason for this change? ANSWER: Lithium is eliminated by the kidney. In late pregnancy the glomerular filtration rate increases substantially and hence elimination of the drug can almost double. Liver biotransformation pathways might also increase the rate of elimination of various drugs, causing lower levels and, potentially, suboptimal therapy. ER -