Its the sorbitol in it that causes your bowels to loosen up,it causes your intestines to pull in that much more water into them.
sweet (literally) i'm trying to fix my problem too...
probably pear juice is working for you because it's super high in fructose, fact the top two fruits with fructose is apples and pears..which a normal person if they drink high amounts of fructose (without sucrose..table sugar) your body usually can only handle about 80 grams before it causes diarrhea issues..so that's probably why you're having better success with it, BUT if it's working by all means stick with it (pears/apples/honey are super high in fructose..as well as corn syrup, that's a big one..high fructose corn syrup..trick is to avoid table sugar or diary which slows the system down but yeah stick with your trick you found..that's the key to beating it..plus pear juice has some nutritional value to it I'm sure with vitamin c..so you can't go wrong there.)
Cool, now I have a remedy next time I am constipated.