My four year old son is taking Xopenex 1.25 three times a day.
Someone gave me two boxes of .63. Can I use two tubes of .63
for one 1.25? Is it safe to use expired Xopenex? The packs have
not been opened. But are old, the date is 8/05.

Regardless of the medication or condition, it is never a good idea to administer outdated medication. The medication is dated for a specific reason, most of which is related to the strength of the medication. Medicine that is beyond its dating can be either weaker or stronger than it should be, which can cause serious health problems, because the proper dosage may not be given. Please, please do not give this to your son without a drs. approval. It could cause him serious health problems.