Page 67 - Dosage 1-part2 -ebook_Neat

30/10/2025, 00:02 Pharmaceutical Solutions & Sterile Dosage Forms

Benzalkonium chloride is the most common preservative used in ocular preparations.

NOTE: Phenol and benzyl alcohol are not used (very irritant).

Sterilization techniques

Formulations are preferably sterilized in their final containers by autoclaving. Alternatively,
filtration can be used (Except for …….)
All primary packaging components must be sterile (gas or irradiation).
Most ophthalmic products are aseptically manufactured and filled into previously sterilized
containers in aseptic environments using aseptic filling and capping technique.

2. Clarity

Eye drops should be free of any foreign particle.
Large particles will cause eye injury.

3. Tonicity

Eye drops are made isotonic with lachrymal fluid (exert osmotic pressure equal to that of tear
fluid generally agreed to be equal to 0.9% NaCl).
Non-isotonic solutions are irritant.
Commonly used ingredients to adjust isotonicity:

NaCl, KCl, buffer salts, dextrose, glycerin, propylene glycol, mannitol

NOTE: borate buffer system has good antimicrobial properties that can boost anti-microbial
efficiency of some preservatives.

4. pH 64/77

Normal tears have a pH of 7.2-7.4 and possess buffer capacity.

Any formulation having a different pH than 7.4 will be neutralized by normal buffers of the tears.

Adjusting the pH is important as pH affects:
Stability of the formulation & Efficacy of the preservative.

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