After completing your graduation you can opt for M.Sc (Nursing).There are lots of specialized areas, like Community Health, Medical-Surgical, Pediatrics Obstetrics and Gynecology, Psychiatry, etc. And there are several other certification courses which are listed below :-
M.Sc in Biotechnology
M.Sc in Neuroscience
M.Sc in Renal Sciences and Dialysis Technology
M.Sc Medical Microbiology and Medical Biochemistry M.Sc. Clinical Research
M.Sc. Medical Sociology
Post Graduate Program in Public Health Management You can even do that or pursue MBA in Pharmaceutical management or Hospital Management.

All the best.