<prompt> Which of the following best explains why Lignocaine has a higher fetal-to-maternal plasma ratio when compared with bupivacaine?Bupivacaine has low molecular weightLignocaine has higher protein-bindingBupivacaine has a lower dissociation constant pKaLignocaine is less protein bound  <response>: Lignocaine is less protein bound than bupivacaine. Unbound form of drug thus easily gets transferred across placenta. 