I disagree Erin. The oral contraceptive pill, containing oestrogens, is absorbed well via the oral route. Otherwise there would be a lot of angry women out there !
Perhaps you were thinking of the problem facing the delivery to the blodstream of drugs based on proteins? Naturally these are chewed up by digestive enzymes and hence have to be given parenterally (that is, not via the gut). This is why diabetics inject insulin (a protein or peptide hormone), yet people with low thyroid function can take a pill by mouth (thyroxine is an iodinated molecule derived from the amino acid tyrosine).
"I never forget a face, but in your case I'll make an exception"
- Groucho Marx