Hypromellose

Hypromellose, short for hydroxypropyl methylcellulose (HPMC), is a semisynthetic, inert, viscoelastic polymer used as an ophthalmic lubricant, as well as an excipient and controlled-delivery component in oral medicaments, found in a variety of commercial products.^[1][2]

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Ophthalmic applications

Hypromellose solutions were patented as a semisynthetic substitute for tear-film.^[3] Its molecular structure is predicated upon a base celluloid compound that is highly water soluble. Post-application, celluloid attributes of good water solubility reportedly aids in visual clarity. When applied, a hypromellose solution acts to swell and absorb water, thereby expanding the thickness of the tear-film. Hypromellose augmentation therefore results in extended lubricant time presence on the cornea, which theoretically results in decreased eye irritation, especially in dry climates, home, or work environments.^[4] On a molecular level, this polymer contains beta-linked D-glucose units that remain metabolically intact for days to weeks. On a manufacturing note, since hypromellose is a vegetarian substitute for gelatin, it is slightly more expensive to produce due to semisynthetic manufacturing processes. Aside from its widespread commercial and retail availability over the counter in a variety of products, Hypromellose 2% solution has been documented to be used during surgery to aid in corneal protection and during orbital surgery.

Excipient/Tableting ingredient

In addition to its use in ophthalmic liquids, hypromellose has been used as an ingredient in oral tablet and capsule formulations, where it functions to delay the release of a medicinal compound into the digestive tract.

References

1. ^ de Silva et al, "Hydroxypropyl methylcellulose (HPMC) lubricant facilitates insertion of porous spherical orbital implants." Ophthal Plast Reconstr Surg. 2005 Jul;21(4):301-2.
2. ^ Williams et al, "Method to Recover a Lipophilic Drug From Hydroxypropyl Methylcellulose Matrix Tablets." AAPS PharmSciTech. 2001; 2(2): article 8.
3. ^ US Pat. No. 5,679,713
4. ^ Koroloff et al, "A randomised controlled study of the efficacy of hypromellose and Lacri-Lube combination versus polyethylene/Cling wrap to prevent corneal epithelial breakdown in the semiconscious intensive care patient", Intensive Care Med. 2004 Jun;30(6):1122-6. Epub 2004 Mar 10.