Thank you for your query.
has a very short half life meaning that the drug is metabolized very fast. It is for this reason that the drug is given very frequently, 5 times in your son's case. At the same time the dose cannot be increased depending on the movements. Hence, a balance has to be struck. With this information it shall be better for you to discuss with the treating doctor and adjust the dose and frequency accordingly.
I hope I have answered your query to your satisfaction.
Wishing your son all the best..