Question

At low pH levels (e.g. stomach) is a weakly basic drug mostly in its ionizable or non-ionizable form?

a) Ionizable
b) Non-ionizable
c) No specific form
d) Variable form

Answer 1

In the acidic environment of the stomach with a low pH, a weakly basic drug is mostly in its ionizable form, as it tends to gain a proton and become ionized in the presence of excess hydrogen ions.

Step-by-step explanation:

At low pH levels, such as those found in the stomach, a weakly basic drug is mostly in its ionizable form. This is due to the fact that in a highly acidic environment, weak bases tend to gain a proton and thereby become ionized. The presence of excess hydrogen ions (H+) in the stomach, where the pH is very low (around 1.7), promotes the ionization of the base because the base wants to react with those hydrogen ions. So, the drug will predominantly exist as its protonated (and ionizable) form under these acidic conditions.