MEDizzy - A 17-year-old boy took a tablet of naproxen for a headache.

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Pharmacokinetics

A 17-year-old boy took a tablet of naproxen for a headache. Naproxen is a weak acid with a pKa of 5.2. W hat percentage of the drug was most likely water soluble in the patient’s plasma?

ExplanationD .An acidic drug is mainly water soluble w hen its pKa is lower than the pH of the medium . The amount of water solubility is proportional to the difference between pH and pKa, according to the following table Difference between pH and pKa Because the pH of plasma is about 7.4, the drug will be greater than 99% water soluble in the patient’s plasma.