What Is Hypromellose (HPMC)? The Lubricant in Many Eye Drops and Gels

Turn over almost any box of lubricant eye drops or eye gel and you will meet the same word in the active-ingredient line: hypromellose. Sometimes it appears as hydroxypropyl methylcellulose, sometimes as HPMC. Here is what it is, what the percentage on the label means, and how the same ingredient ends up in both thin drops and thick gels.

Hypromellose in plain words

Hypromellose is a cellulose derivative: a polymer made by modifying cellulose, the structural fibre of plants. It dissolves in water and forms a smooth, slightly viscous solution. Medicine and food manufacturers use it widely as a thickener and coating. In eye care it acts as a lubricant, which regulators call a demulcent.

One ingredient, several names

All of these names refer to the same substance:

• Hypromellose, the standard name on US drug-facts panels
• Hydroxypropyl methylcellulose, the full chemical name, common on international packaging
• HPMC, the abbreviation

The Eyemist Gel carton, for example, reads Hydroxypropyl Methylcellulose (Hypromellose) Ophthalmic Gel 0.3%. The label gives both names on purpose.

Where hypromellose fits under US rules

In the US, over-the-counter eye lubricants follow the FDA's monograph for ophthalmic drug products. The monograph lists cellulose derivatives, among them hypromellose, carboxymethylcellulose sodium, hydroxyethyl cellulose and methylcellulose, as ophthalmic demulcents at 0.2% to 2.5%. The uses allowed on the label are along these lines:

• for the temporary relief of burning and irritation due to dryness of the eye
• for the temporary relief of discomfort due to minor irritations of the eye
• for use as a protectant against further irritation or to relieve dryness of the eye

That is why hypromellose eye drops and gels describe their purpose as "lubricant" and word their uses so similarly. The wording comes from the monograph.

What "0.3%" on the label means

The percentage is the amount of the active ingredient in the product. Hypromellose 0.3% means 3 mg of hypromellose per gram (for a gel) or per millilitre (for drops). It is one of the most common strengths in both formats. When you compare two products, check that the active ingredient and its percentage match before comparing anything else.

Hypromellose eye drops vs hypromellose eye gel

The same 0.3% hypromellose can appear in a thin drop or in a thick gel. Thickness is not set by the active ingredient alone: it depends on the whole formulation, including the inactive ingredients that build the gel. So two products with an identical active-ingredient line can feel quite different.

• Hypromellose eye drops are light and convenient for daytime top-ups
• A hypromellose eye gel has a thicker texture that coats the eye. Many people prefer it for the evening or before sleep, because it can blur vision briefly

The trade-offs are covered in eye gel vs eye drops.

Dextran 70 and hypromellose

Some drops list two actives: dextran 70 0.1% together with hypromellose 0.3%. Dextran 70 is another polymer lubricant. Under the monograph it may only be used together with a second polymeric demulcent such as hypromellose, which is why the two appear as a pair. Eyemist Gel uses hypromellose 0.3% as its only active ingredient.

A quick label checklist for hypromellose products

1. Active ingredient and percentage: hypromellose, and how much
2. Sterile: the word should be on the carton, with a sealed tube or bottle
3. Preservative: multi-use products contain one. Eyemist Gel uses sodium perborate
4. Format and pack size: drops or gel, and how many grams or millilitres
5. Directions and warnings: how much to apply and when to stop and ask a doctor

For a worked example of comparing two eye-gel labels line by line, see choosing a lubricant eye gel.

This article is general information, not medical advice. Stop use and ask a doctor if you have eye pain, changes in vision, continued redness or irritation, or if the condition worsens or lasts more than 72 hours.