The drug I have heard of for PTSD is propanolol. It's main use is to treat high blood pressure, so if you have really low blood pressure, you would not want to take this. First it was given to people who had just been involved in potentially traumatizing events, like car accidents, and it helped reduce the development of PTSD by those in the accident. But now it is in trials to help people who already have PTSD. I believe the treatment involves having several sessions with a therapist trained to help you recall the traumatic event, and if this is done, coupled with the drug, then the PTSD can be lessened. Or so the thinking goes... But it does involve reactivation of the memory.

Here is a link to learn more:
http://clinicaltrials.gov/ct2/show/NCT00645450