My dr. changed my 100mg nucynta every 4hrs to 200mg ER every 12hrs and was wondering what makes the ER different from the regular 100mg other than its coated and doesnt release all at once? Will it help to relieve the pain as much or better since 100mg every 4hrs is more mg's in a 12hr period than the 200mg ER every 12hrs. I have several ruptured and herniated disk in my cervical and lumbar sections of my back,i also have some cracked and bulged disk in the thorasic area and have had several surgeries to fix the other problems i got from being ran over by a car a few yrs ago.The surgeries ive had took care of the life threatning injuries that occured from the accident.