I have graduated recently with Bachelor of Pharmacy in overseas and I am interested to study chemistry in USA. I do not know what PhD chemistry program (except medicinal chemistry) I can apply. Hence, I would like to get some advices.

This would depend largely on where you want to apply and what your technical experience is. Given your degree, you'd likely be looking at some sort of med chem project. Specific projects are dependent on the research group you are wanting to join. You can look these up through university websites.

 

At the end of the day, these are probably questions best asked of the universities you were hoping to apply to.

Apart from med chem, what other options I have

I have no idea, as I have no idea what your experience is in research wise and where you plan on applying. What do you want to do?

A few other comments: Getting accepted into a graduate program depends on how comparable your degree is to your chosen field, your GPA and results from admissions tests. Different universities will have more specific requirements, as will different research groups. These are ultimately the people you should be talking to, but I would advise you 1. have a realistic view of where your knowledge lies and how motivated you are to make up the areas you lack knowledge on and 2. you have an idea of what area you want to go in to.

I am interested in organic chemistry and want to do research related to organic chemistry. During my undergraduate (Bachelor of Pharmacy), I have been a research assistance for organic synthesis work for a month and I also have a research project related to polymer chemistry.