Well you survived the interview! The interviewer was human afterall (!) and you have performed very well.
Your work is not done!
To focus your efforts to find work in this area you should be keeping faithful records of what agencies you are working with, what companies your CV has been sent to and finally an analysis of each interview
Approaching the job search with such a degree of organization will yield terrific results.
Reviewing the interview:
This interview may have been a first round interview, in which case you will need your notes to prepare well for a second round interview.
Record who interviewed you and retain their business card
Record what went well and what did not go so well
Think what you might say differently if you are granted a second round interview
Make notes and refer to these notes over the coming days as you prepare for a second interview
During the course of the interview you should have been given a business card for the person interviewing you
Immediately after the interview send a simple, handwritten note of thanks to the interviewer.
It should read as follows:
Dear Ms Blog
Thank you for taking the time and trouble to interview me for the position of Medical Sales Representative on the South Dublin territory with Pfizer.
I am really interested in the position, more so now that I have met with you. I really feel I could work very well for you.
I look forward to having the opportunity to meet with you again.
A simple thank you note will help you stand out from the crowd and even if you do not get a second interview, the Pharmaceutical/Medical Sales world is small and your paths will cross again over the next few years.
Good luck with all those interviews!