Adding polyethylene glycol (PEG) to an interferon has which pharmacologic effect on the interferon?

Question

1. Increased protein binding
2. Increased drug half-life
3. Decreased cellular permeability
4. Decreased first-pass effect

Answer 1

Correct Answer: 2
Rationale 1: The addition of PEG does not have an effect on protein binding.
Rationale 2: The addition of PEG increases the interferon's half-life.
Rationale 3: The addition of PEG does not decrease the cellular permeability of the interferon.
Rationale 4: The addition of PEG does not affect first-pass effect; because it is administered parenterally, it avoids the first-pass effect.
Global Rationale: PEG is a polymer with low toxicity that can be found in skin creams, laxatives, lubricants, toothpastes, and many other products. The addition of PEG to another molecule, known as pegylation, increases the molecule's solubility and extends its stability. The addition of PEG to an IFN extends the half-life of the drug to allow for once-weekly dosing. This action does not have an effect on protein binding, does not decrease cellular permeability and does not decrease first-pass effect.