Page 28 - Laboratory manual for students FAR222 2019 20

FAR 222 Dosage Form II Laboratory Manual

COMMONLY USED ISOTONIC VEHICLES FOR OPHTHALMIC PRODUCTS

1. Isotonic sodium chloride solution
Sodium chloride 0.9 %w/v
Benzalkonium chloride 0.01 %w/v
(Sterile) distilled water q.s. ad 100 mL

2. Boric Acid Vehicle (pH 4.7), almost iso-osmotic with human tears
Boric acid 1.9 %w/v
Suitable preservative e.g. benzalkonium chloride 0.01 %w/v
(Sterile) distilled water q.s. ad 100 mL

3. Special boric acid vehicle
Boric acid 1.9 %w/v
Suitable preservative e.g. phenylmercuric nitrate/acetate 0.002 %w/v
Sodium sulfite, anhydrous 0.1 %w/v
(Sterile) distilled water q.s. ad 100 mL

4 Isotonic Phosphate Vehicle: Sorensen’s phosphate vehicle (pH range 5.9 to 8.0)

Sodium chloride
Volume of 0.0667 M Volume of 0.0667 M (2.39%w/v)
pH (1.04%w/v) sodium acid disodium hydrogen phosphate required for
isotonicity
phosphate dihydrate* (mL) dodecahydrate* (mL)
(g/100mL)
5.9 90 10 0.52
6.2 80 20 0.51
6.5 70 30 0.50
6.6 60 40 0.49
6.8 50 50 0.48
7.0 40 60 0.46
7.2 30 70 0.45
7.4 20 80 0.44
7.7 10 90 0.43
8.0 5 95 0.42
Sodium acid phosphate dihydrate, ∆Tf 1% = 0.207°C
Disodium hydrogen phosphate dodecahydrate, ∆Tf 1% = 0.127°C

* use the same salt in the preparation regardless of the hydrate form

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