Which of the following drug does not cross the placental barrier?
Heparin does not cross the placental barrier due to its high molecular weight and its negative charge. So it is the anticoagulant of choice during pregnancy. Ref: Drugs During Pregnancy and Lactation By Christof Schaefer, Page 86 ; Essentials of Medical Pharmacology By K D Tripathi, 5th Edition, Pages 561-3
Heparin
Morphine
Phenytoin
Diazepam