Nass contains Carboxymethylcellulose, an ionic polymer with carboxyl and hydroxyl groups and a tear film mucin-like chemical structure. It is a lubricant with protective properties and auxiliary in eye wetting, providing refreshing relief for dry or irritated eyes, due to the similarity of its composition with that of tears.

Mechanism of action

The carboxymethyl cellulose mechanism of action is based on its physical properties that provide a lubricating effect, increasing the tear viscosity due to its mucoadhesive action, forms a film that protects the conjunctiva and corneal epithelium from mechanical irritation and friction of the eyelids, facilitating the regeneration of injured tissues. Finally, its prolonged residence time in the eye results in relief of the symptoms of tear deficiency.

Pharmacokinetics and pharmacodynamics

Carboxymethylcellulose is pharmacologically inert and due to its high molecular weight it is not expected to be absorbed systemically after topical administration of sodium carboxymethylcellulose. Its pharmacological properties are not mediated by the receptor but by its physical, pseudoelastic and mucoadhesive properties, which provide a long stay in the eye.

Therapeutic indications

Nass is indicated for temporary relief of eye discomfort, such as: burning sensation, irritation or discomfort caused by a decrease or absence of tears and / or environmental conditions. It is indicated to lubricate and re-moisturize soft and rigid contact lenses, to relieve the dryness, irritation, discomfort and blurred or itchy vision associated with the use of lenses.


Hypersensitivity to the components of the formula.


Each ml contains:

Carboxymethylcellulose Sodium 7.0 mg

C.S. excipients 1 ml

Posology and administration 


Administration route: Ophthalmic.

Instill 1 or 2 drops into the eye (s), as needed.


Keep at a temperature between 15 °C and 25 °C. Protect  from freezing.


Box containing a 15 ml dropper bottle.

Side Effects


Nass is generally well tolerated. Some patients may experience blurred vision transiently, due to its viscosity.

General precautions

To avoid contamination of the container, the tip of the bottle must not touch any surface. Replace the cap after use. Do not use if the solution changes color or becomes cloudy. Stop using Nass and consult your doctor in case of eye pain, vision changes, continued redness or eye irritation. Use before the expiration date marked on the container. Sodium carboxymethyl cellulose can cause transient blurred vision that could affect the ability to drive vehicles or operate machinery; therefore the patient must wait for his vision to clear before performing these activities.

Use restrictions during pregnancy and lactation

There is no evidence about it so far. Carboxymethyl cellulose is not expected to be absorbed systemically; therefore, it is not expected to be excreted in human milk.

Drug interactions

There is no evidence about it so far.

Effects of carcinogenesis, mutagenesis, teratogenesis and fertility

There is no evidence about it so far.