Tingly, if what you are talking about is the same as I stuff I was prescribed in Mexico many years ago (1989 to be precise) for an irritable bladder problem then it is brilliant - it was a life saver for me after taking just one tablet. In my case, the problem was caused by using a diaphragm with gel for contraception purposes and it was sheer hell, I was literally rolling around on the floor of the hotel room all night with acute burning and I was constantly urinating. The bad news is, once you have an attack of something like that, it can always flare up again.
The brand name is Pirifur or Azuron and it contains Acido Nalidixico 500mg and Clorhidrato de Fenazopiridina 50mg. Sorry that is the Spanish name for the ingredients but having just checked, I am pretty sure it is the same as the stuff you are taking. If so, it is the only thing that has ever worked properly for me and I was told it is OK to take it sometimes. It makes your urine go orange!