Hello,

If you're enquiring regarding optional subject for UPSC then pharmacy as a subject isn't included in the list yet unlike in case of a medical graduate who has the option to choose medical science, in your case a subject in the list that you can be well acquainted with will be Chemistry, you can have that as an optional, another important thing to remember here is syllabus of optional subject in UPSC is nothing short of graduation level, also availability of study materials too have to be taken into consideration of course apart from an interest towards the subject else the study itself will get very tiring and one may find it difficult to cope with such extensive syllabus.