The Doctor Has Increased The Gabapentin From 300 Mg. 2

The doctor has increased the gabapentin from 300 mg. 2 x's a day to 400 mg. 3 x's a day. My husband was just issued a new prescription of the 300 mg. Can he take 3 of the 300 mg. in the am, 2 at noon and 3 at night. Both ways, it totals 2400 mg? the only difference I see is the 400 has red iron dioxide in it. Does this make a difference? Thanks.