Hi Binita
A change in diet does help to tackle constipation. Include banana in his diet and raw carrot. Avoid yoghurt, potatoes, cooked carrot. Make him drink plenty of fluids. My son also has constipation and green beans helps him. The idea should be to add a lot of fiber in his diet.
Do you mean to ask if he can take Asunra at night? If so yes he can take the medicine at night. If you meant to dissolve the medicine at night and give him later in the morning then its no, you have to take it within a few minutes its mixed. The medicine doesn't dissolve very well in juice, so what I do is take a little water add the med, wait for a few minutes and then add the juice. Whats your childs weight and for how long has he been on asunra? Any time could be the best time as long as you give the med daily at the same time. But if there are any stomach issues or appetite problems then giving the med at night helps.
take care
maha