I have a sinus infection and am on methylprednisolone. last night i fell asleep before taking my bedtime dosage; just realized it now that i took my morning dosage. how do i catch up? can i take the 2 missed pills with my after lunch dosage?

Depends on details: There's no strict rule about how to do this. Also, it depends on the illness, the patient, the drug dose, etc... Sometimes, especially milder cases, a patient might not need to "catch up." Other times, such as in bad asthma attacks, the doctor may want the patient to "catch up." A lot of times, people just do an "in between," such as taking 1 of the 2 missed pills and ignoring the other one.