Many POTS patients have been prescribed beta blockers, Flourinef and Midodrine to try to alleviate their orthostatic symptoms. For some people, these work, but for many others, they do not.
Autonomic experts have used other drugs like Octreotide and Ritalin on some patients, but this practice is not widespread and many doctors who are not experts in autonomic disorders probably don't feel comfortable trying "unproven" drugs on a POTS patient. Here are two recent retrospective research studies on the success of using Octreotide and Ritalin in POTS and OI patients from Dr. Blair Grubb's team at the University of Toledo Medical Center:
Use of methylphenidate in the treatment of patients suffering from refractor postural tachycardia syndrome.