@dasunbehagen The medication is delivered into the intrathecal space around the spinal cord. Literature states that the med does not pass the blood/brain barrier (it doesn't go into the general body systems), so no real side effects. I have not experienced any weight gain. Most pumps are implanted inside the abdomen just under the skin. This is so the port can be easily accessed for refilling(about every two to three months). The pump is about the size of a hockey puck, so a small incision 1-2" is made on your front, side abdomen. Tubing is fished around to your back where a small incision is made in order to place a catheter(needle) into the spinal canal and then attached to the tubing. Hope that answers your questions.