Where are weak bases ion trapped?

Where are weak bases ion trapped?

• A. Small intestine
• B. Stomach
• C. Colon
• D. Blood

Answer: (B)

Weak bases become protonated in acidic environments, turning into charged conjugate acids that cannot cross lipid membranes easily. This causes the drug to accumulate in the compartment where the pH is very low. The stomach is highly acidic, with a pH around 1–3, so a weak base will be protonated there and trapped as a charged species. In the small intestine, colon, or blood, the pH is higher, so the base remains largely uncharged and can cross membranes, resulting in less trapping. Therefore, the weak base is ion trapped in the stomach.

Weak bases become protonated in acidic environments, turning into charged conjugate acids that cannot cross lipid membranes easily. This causes the drug to accumulate in the compartment where the pH is very low. The stomach is highly acidic, with a pH around 1–3, so a weak base will be protonated there and trapped as a charged species. In the small intestine, colon, or blood, the pH is higher, so the base remains largely uncharged and can cross membranes, resulting in less trapping. Therefore, the weak base is ion trapped in the stomach.