Page 6 - Laboratory manual for students FAR222 2019 20

FAR 222 Dosage Form II Laboratory Manual

Thus, we require the addition of 2.3 %w/v anhydrous dextrose to make the sodium chloride
solution isotonic with serum.

Thus, the amount of anhydrous dextrose needed = 2.3 × 150 = 3.45
100
You require 3.45 g of anhydrous dextrose to prepare 150 mL of an infusion containing
0.5 %w/v sodium chloride isotonic.

iii. Preservatives

These must be included in all parenteral products presented in multi-dose containers, unless
the product monograph specifies otherwise. The preservative should be bactericidal and
fungicidal, and compatible with both the product and the container.

Commonly used preservatives are shown in Table 1.

Table 1 Commonly used Preservatives for Parenteral Products (Source: BPC 1973)

Preservative Usual concentration (% w/v)
Benzalkonium chloride 0.01
Benzethonium chloride 0.01
Benzyl alcohol 2.0
Chlorbutol 0.5
Chlorocresol 0.1 – 0.3
Cresol 0.3 – 0.5
Methyl hydroxybenzoate 0.18
Phenol 0.5
Phenethyl alcohol 0.5
Phenylmercuric acetate and nitrate 0.002
Propyl hydroxybenzoate 0.5
Thiomersal 0.01

iv. Buffers

These must be included in parenteral products which need pH adjustment. This could be
achieved by using common buffers as shown in the appendices; or using alkaline medium e.g.
sodium hydroxide or acidic medium e.g. hydrochloric acid to adjust the pH of solutions.

4