Sorry for the delay given that I don't log on to this site on a daily basis. To make the story brief, different classes of laxatives exist on the market with different mechanisms of action and each physician has his/her own receipe. Some may cause serious adverse effects such as eletrolytic disbalance and therefore not suitable in renal failure patients. They are usually well tolerated by healthy subjects though kids tend to be more easily dehydrated if the medication is overused. The drug monographs are available online. A quick googling will fetch you the info needed. If you search by the drug generic name, you will get a list of commercial names with it.
Softener: Colace
Bowel peristaltism stimulant: Senokot
Osmotic agents: sorbitol, lactulose
Bulking agent: Metamucil
Fleet enemas: glycerin, castor oil, mineral oil, sodium phosphate,...
Cheers!