I thought I saw something like this in one of my nutrition classes in college. Take it for what you will, grain of salt:
"Secondly, powdered vitamins both boast better absorption rates than pill-form supplements. According to the widely used medical reference book, Physician's Desk Reference (page 1542), liquid (drinkable) supplements can be absorbed up to 98%. Where as it states the absorption rates of pills is 5%-18%. This means that 80-95% of the ingredients contained in pills are excreted or eliminated from the body. Pills also contain binders and fillers such as starch, sugar and talc which make digestion not only slower, but actually harder on the body to absorb."
Not saying it's gospel. Just that I know tablets are poorly absorbed. I know caplets are a different story.