Page 57 - Dosage 1-part2 -ebook_Neat

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

2. Solvents for injection

Constitutes the highest proportion of the formulation.
Should be non-toxic and inert.

A. Aqueous vehicles:

A1. Water:

Water for injection (WFI) is completely free of pyrogens and of high chemical purity.
WFI can be prepared by distillation (BP) or reverse osmosis (USP).

A2. Water with Co-solvent:

Water-miscible solvents are mixed with water in some parenteral preparations (why?)
Enhance solubility of some drugs.
Act as stabilizers (reduce hydrolysis).

The most common used co-solvents: glycerin, ethyl alcohol, propylene glycol and PEG

Higher concentrations may be toxic, irritant and painful (ethanol)

Can be given both IV and IM.

B. Non-aqueous vehicles:

Major class of non-aqueous solvents is fixed vegetable oils.
Example: Corn oil, cottonseed oil, peanut oil and sesame oil, soyabean oil.

The oil in the product must be stated on the label as Some oils may cause sensitivity
reactions to some patients.
NOTE: Mineral, volatile and animal oils are never used in injections.

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