Yes you can pursue MSc Drug Chemistry course (also known as MSc Pharmaceutical Chemistry) after completing course in BSc Chemistry. All you need to have is 50% aggregate marks in your BSc. The admission is usually on the basis of past merit record of BSc. However, some colleges do conduct entrance exams as well, few of which are listed below -

• Indian Institute of Technology Joint Admission Test (IIT JAM)
• Banaras Hindu University Postgraduate Entrance Test (BHU PET)
• Calicut University PG Entrance Exam
• Kerala University M.Sc. Chemistry Entrance Exam
• Cochin University of Science and Technology Common Admission Test (CUSAT CAT)
• Osmania University Common Entrance Test (OUCET)
• Mahatma Gandhi University Common Admission Test (MGUCAT)

To get more details about MSc Pharmaceutical Chemistry, you may visit the link - Pharmaceutical Chemistry Course, Subjects, Syllabus, Colleges, Admission, Career (careers360.com)