Products
Purified water is available in pharmacies and drugstores. Specialty retailers can either make it themselves or purchase it as a finished product from specialized suppliers.
Structure and properties
Water (H2O, Mr = 18.015 g/mol) exists as a clear, colorless liquid without odor or taste. Purified water is prepared from drinking water by the following methods:
- Distillation
- Ion exchanger
- Reverse osmosis
- Other suitable method
It must not contain fecal germs, preservatives or additives and must meet the other physical, chemical and microbial requirements of the pharmacopoeia. Purified water has a limited shelf life. Freshly opened bottles expire after one day at room temperature and after one week in the refrigerator.
Indications for use
Purified water is used in the pharmaceutical industry for the preparation of drugs that do not need to be sterile or pyrogen-free. These include, for example, oral solutions, syrups, extracts, creams for external use and liniments (selection). It can also be used to clean equipment and containers, provided they do not have to be sterile/pyrogen-free. Ordinary drinking water is hardly used in pharmacy. An exception is the preparation of antibiotic suspensions for children. Drinking water contains, for example, calcium and magnesium salts, which may be incompatible with active pharmaceutical ingredients and excipients.
Precautions
Purified water rapidly becomes bacterially contaminated. Appropriate precautions must be considered during preparation, filling, and storage. The ideal procedure is well documented in the literature with detailed information. Furthermore, purified water should not be drunk.