Since the intestinal pH is near neutral (pH 5-8), both weak bases and weak acids are nonionized and are usually readily absorbed by passive diffusion.    From Wordnik.com.  [Absorption of toxicants] Reference

The stomach, having high acidity (pH 1-3), is a significant site for absorption of weak organic acids, which exist in a diffusible, nonionized and lipid-soluble form.    From Wordnik.com.  [Absorption of toxicants] Reference

Extracellular PH and Pka of the drug: nonionized.    From Wordnik.com.  [Recently Uploaded Slideshows] Reference