Niaspan absorption

Without medication, I run a very high triglyceride level (> 1000). I also run an elevated LDL and a low HDL.

I have always exercised (run 8-12 miles a week followed by some free weights) and my diet includes whole grains and few sugars or alcohol.

I currently take Lipitor (10 mg) in the morning with oatmeal at 7 AM.
I take an aspirin (81 mg) at 8 AM.
I eat an apple or a pear at 8:30 AM or 9 AM, followed by 500 mg of Niaspan.

Here's my problem (my apologies for this topic):

The Niaspan passes through me undigested.
Anyone know anything about this?

(I also take Tricor, 145 mg, in the evening, along with another Niaspan, 500mg, at night before bed.)

Thanks.