Page 79 - Community pharmcy practice E-book 2025

02/11/2025, 00:10 Otic & Ophthalmic Disorders | Dermatological Disorders

B. Ocular osmoprorectants (osmotic protective agents)

These substances work by entering the cells and helping to balance the internal osmotic pressure, thus

stabilizing cell volume, stabilizing proteins, and inhibiting inflammation.

Examples of ocular osmoprotectants include:

Polyols: Glycerin, erythritol, sorbitol, trehalose, inositol.

Other solutes as: L-carnitine, Betaine, glycine, taurine, proline.
Excipients

Preservatives: Benzalkonium chloride (BAK) is the most common preservative used in ocular
preparations.

Preservatives- free products are less likely to irritate the ocular surface than those with preservatives.

Long-term use of topical products containing BAK can lead to damage of conjunctival and corneal
epithelial cells (Not suitable for chronic diseases).

Preservative-free products or those with less toxic preservatives as Purite® are preferred in patients
with moderate to severe dry eye disease.

Mineral oils or vegetable oil as castor oil, flaxseed oil are used to mimic the lipid layer of tear film
and reduce evaporation.

Buffers: to adjust pH to 7.2-7.4 as in normal tears. Examples: Borate & phosphate buffers are the
commonly used in ocular formulations.

Tonicity adjusters: Commonly used ingredients to adjust isotonicity: NaCl, KCl, buffer salts, dextrose,
glycerin, propylene glycol, mannitol.

Administration guidelines for use of artificial tears

In most mild cases of dry eye disease, a regimen of at least twice-daily drops is a good starting point.
For more severe cases, the dosage can be increased to 3–4 times daily.
If the patient's clinical needs and response to therapy indicate the need for more frequent use, these
solutions may be given as often as hourly.
In many cases, use of artificial tears may be continued indefinitely, depending on patient response.
Preservative-free products or those with less toxic preservatives (e.g., Purite [sodium perborate]) are
preferred in patients with moderate to severe dry eye disease or those who are sensitive to such agents.
If using a suspension, shake the container well before instilling.
If using the suspension with another solution dosage form, place the suspension drop last because it has
prolonged retention time in the tear film.

78