Excipient (pharmacologically inactive substance)

What is it?

Hypromellose phthalate (hydroxypropyl methylcellulose phthalate, or HPMCP) is a phthalic acid ester of hydroxypropyl methylcellulose. In the pharmaceutical industry, hypromellose phthalate is used as a coating agent for tablets and granules. It is a colorless, odorless white powder.^[1]

Hypromellose phthalate was introduced in 1971 as a cellulose derivative for enteric coating. An enteric coating agent is used to protect drugs from degradation by gastric acid or to present them from causing side effects in the stomach. It is widely used as an enteric coating agent by the pharmaceutical industry. HPMCP has been admitted into the U.S. National Formulary (US/NF). HPMCP is also used in sustained-release preparations, in binders and as microcapsule bases.^[1]

There has been some concern over the use of phthalates in medications, total exposure to phthalates, and possible toxicity, although specific research is lacking. The FDA is aware of the use of phthalates in pancreatic enzymes. Phthalates are included in its list of inactive ingredients for FDA-approved drugs.^[2] Phthalates are known to be excreted in the urine, although data on accumulation is not known.