Question

Calculate the ratio of ionized and non-ionized forms of scopolamine drug in the stomach (pH = 1.66) and intestine (pH = 8.66) if its pK = 7.66. Where will the drug be absorbed: in the stomach and/ or intestines?

Answer 1

Ionized (or charged) drugs are not absorbed as efficiently as un-ionized drugs are. Practically speaking, this means that if taken orally, a drug that is a weak acid will be absorbed primarily in the acidic environment; whereas, a drug that is a weak base will be absorbed in the alkaline environment small intestines.