I'm working as a lecturer in Pharmacology in Kathmandu University Medical School, Nepal. I'm trying for the my PHD in Pharmacology in USA.. I came to know that before processing for the application, we need to arrange the supervisor for our research.. I've tried a lot and finally gave up.. Because every Prof. I've contacted they were very positive about me, but they told me that this time no vacancy, better try next time..
I want to know from you guys out there that what should be the better way for processing the application? something.

The approval of the supervisor is alone not mandatory if you require to do PhD in USA. You have certain general requirements that you should fulfill for applying to the grad school. They are the general GRE test and an English requirement test e.g. TOEFL.

Besides these you should fulfill all the categories in the application form a prior research experience in your field is mandatory for applying to US universities. You should be very strong candidate to apply directly to research programs even if you have all these requirements. If not you should first apply and get selected for MS degree or it will be best if you clear GRE SUBJECT TEST (ie biochemistry cell and molecular biology since in your case you are seeking for research in pharmacology). Visit www.gre.org to get information on all the tests.

The advantage of the MS program as international student to USA will help you in several ways. For example you will be allowed to take up chances to work with various research groups of the dept so that the chances of you choosing a suitable research area and group is brightened.Although the process takes a long time you can will be out of the university as a well trained candidate. Only thing is you will enjoy your 5-6 years of grad school if you really love research and earnestly want to do one.