My dad was released from the hospital with chf and given carvedilol 25mg 2x daily. i've read patients start with 3.125mg. why was his dosage different?

Depends: You're correct that the typical starting dose is 3.125mg. If he had high blood pressure, diastolic dysfunction, or some other specific cardiac abnormality other than chf, this may have been the reason why he was started at a much higher dosage. I would discuss this with his cardiologist. If he is experiencing dizziness with rising from a seated or laying position, call them sooner.

Everybody is differe: Everybody is different and his dose was probably titrated up according to his blood pressure and pulse rates.

Beta blocker: Your father was either changed from previous beta blocker at hight dose and chnaged to hospital formulary. Or he was in a lower class of CHF that he may tolerate that dose.

Potentially too high: The usual starting dose for new onset systolic heart failure is 3.125 mg. Two possible explanations for his dosing: 1) he had previously been on a similar dose or 2) his CHF was dominantly diastolic heart failure due to uncontrolled hypertension and the Carvedilol dose was for BP control.

You are right: The dosage should start low and build up to the max dose that you mentioned, 25mg bid. If his blood pressure is tolerating the higher dose, than it may be fine, however, if he feels tired and weak, the he may need to be on the lower dose of Coreg (carvedilol) to start out with and build up to the max dose.