Dear applicant compared to Pharmaceutical Chemistry and Pharmaceutics there are less questions asked from Pharmacology in GPAT. You will have 28 questions from this part, firstly try to follow KD Tripathi thoroughly and simultaneously read the highlighted box portions from Rang n Dale ans the drug interaction part is better written in their book. Now coming to last moment suggestion, read all the possible pages of Pharmacology from Pearson, overall the past few years papers would give you more hints.

Good luck!!