Which statement about physicochemical factors altering the biological performance of drugs is correct?

• A. I only
• B. II only
• C. III only
• D. None of the above - All statements are correct

Answer: (D)

Biological performance of a drug is shaped by its physicochemical properties because these properties determine how much drug is absorbed, how it distributes in the body, how it is metabolized, and how long it remains active. Solubility and dissolution rate set the amount that can enter the bloodstream from the dosage form. Lipophilicity influences the ability to cross membranes and reach various tissues. The ionization state (pKa) affects both solubility and permeability, and this varies with pH along the GI tract and in different compartments. Stability and solid-state characteristics like polymorphism influence how much intact drug reaches systemic circulation and how readily it dissolves. Formulation choices, such as salt forms, particle size, and crystal form, further tune these properties. If each statement describes a valid way physicochemical factors can alter how a drug behaves in the body, then all statements are correct.