How eye drops are prepared pharmaceutically ?

Preparation of eye drops


1. Preparation of bactericidal or fungicidal vehicle


2. Solution of medicament and adjunct


3. Clarification


4. sterilization

Preparation of bactericidal or fungicidal vehicle

Phenyl mercuric nitrate or Acetate are incompatible with aluminum
and strongly absorbed by rubber


Solutions of Phenyl mercuric salts lose potency in polythene containers


Phenyl mercuric nitrate tend to deposit mercury on storage.

Chlorhexidine acetate slightly degrades in autoclaving and is inactivated by cork.


Benzalkonium chloride is absorbed by PVC.


All these solutions require protection from light.


Dissolution of medicaments and adjuncts

Chloramphenicol eye drops: the antibiotic is more soluble in borax
boric acid vehicle (pH 7)


Heating assists the dissolution of preservative. But the solution must be
cooled before dissolving antibiotic.


Clarification:

Microporous plastic membrane filter (0.8micrometers: Millipore AA grade)


Sterilization:

Heating in an autoclave


Maintaining at 98 – 1000C for 30 minutes in the presence of a bactericide
for the drugs like chloramphenicol, cocaine hydrochloride, neomycin sulphate and
physostigmine sulphate in an electrically heated anodized aluminum water bath.


Filtration: filters should retain Pseudomonas aeruginosa (1.5 x 5µ)


Millipore GS type: 0.22µ ± 0.02 µ; HA type: 0.45 µ ± 0.02 µ


Filter diameters: 13mm (suitable for few 10ml portions), 25mm
 (suitable for 100-1000ml), 90mm (few liters).
A pressure difference of 1.3 to 1.7 bars preferred.