Below is a master formula of enteric-coated naproxen tablets.

Other excipients: Brown Iron Oxide, Carnauba Wax, FD&C Yellow #6 Aluminum Lake, Hydroxypropyl methylcellulose, Methacrylic acid- ethylacrylate copolymer, Polysorbate 80, Propylene Glycol, Shellac, Titanium Dioxide, Triacetin, Triethyl Citrate.

a) Explain the role of each of the ingredients in the tablet core of the formulation.   (4 marks)

b) What is the function of enteric coating? Which excipient is responsible for the enteric drug release?   (2 marks)

c) Naproxen can also be formulated as extended-release tablet. Discuss how you may change the formulation to achieve extended-release formulation.  (4 marks)

d) Use appropriate diagrams to illustrate the drug release profile of (i) naproxen enteric coated tablet; (ii) naproxen extended release tablet; and naproxen uncoated tablets in a pH 4.5 buffered solution.  (5 marks)