How does the ionization of a weak acid drug (e.g., Aspirin) in alkaline urine affect its renal excretion?
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Correct answer: It increases excretion by trapping the ionized drug in the tubule
In alkaline urine, weak acids become more ionized (charged). Since ionized molecules are less lipid-soluble, they cannot easily diffuse back across the tubular membrane into the blood, a phenomenon known as 'ion trapping'.
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