I've done a lot of experimenting with drugs to treat LAR syndrome. After quite a long search, I'm finding that Pentasa has some promise. It's an extended-release capsule with mesalamine as the active drug. Lower doses seem to work better. I've tried 800 mg generic coated caplets and it was too strong, producing constipation. Then I tried the 250 mg extended-release brand name capsule. It was still a bit too strong, so I'm now taking the capsule apart and mixing half of it with applesauce after the evening meal. The suppositories weren't useful as they produced leakage.
I found that larger doses produced both constipation and some nausea. I'm hoping that the 125 mg is the sweet spot. The drug calms down bowel contractions and tends to improve stool formation, reducing fragmentation and producing more normal stools. This has a big benefit in reducing cramping, rectal irritation, and hemorrhoids. Not everyone may experience the nausea, so a higher dose may work for some. It also produces a more settled feeling throughout the day, meaning less of a feeling of urgency except right after a meal.
This could be worth exploring with your GI specialist if you're looking for some relief from LAR syndrome. If anyone has tried it or plans to, please post back here with your findings. There seems to be no literature on it for this use.
Male, false negative colonoscopy age 48
DX: 12/2010 rectal cancer age 51
Stage T3N0M0 2 cm from anal verge
neoadjuvant rad/chemo Xeloda
Rectal resection (open surgery) straight anastomosis
Xeloda round 2
ileostomy reversal 11/2011
Successful adhesion X-lap 8/2013
Ongoing LAR syndrome but NED 6 years