Compendial Waters in International Pharmacopoeias
Water is employed as ingredient in many processes, formulations and products. The International pharmacopoeieas (USP, EP, JP) define as “Water For Injection” only the compendial water used as an excipient to parenteral solutions. ISPE Glossary distinguishes
– WFI in bulk: “Water for the preparation of medicines for parenteral administration when water is used as a vehicle”;
– Sterilized WFI: ” (Water) for dissolving or diluting substances or preparations for parenteral administration before use”.
The finished water meets all the chemical requirements for PW (Purified Water). With an additional bacterial endotoxin parameter, is the specific WFI character. Since endotoxins are produced by microorganisms that are prone to spread in the water, the equipment and the procedures used by the production lines to purify, store and distribute WFI must prevent the build-up of endotoxin and minimize microbial contamination in the system.
Distillation is the main way to produce Water for Injection
The main metod of WFI production is distillation; most pharmaceutical WFI is produced by this system. EP pharmacopoeia admits only distillation as a method for producing compendial Water For Injection. USP pharmacopoeia admits also a “purification process proven to be equal to or superior to distillation”, while JP pharmacopoeia admits, in addition to distillation, the reverse osmosis (RO) plus ultra filtration (UF). However, all three pharmacopoeias pose the same limit for the endotoxine level (0.25 euml), for TOC values, (ppb ≤ 500), for the bacterial load (<10, Colony-Forming Units / 100 mL) and for the value of conductivity (1.3 µS/cm@25°C).
There are two basic technologies, that have marked the history of the pharmaceutical industry: the Vapor Compression (VC) distillation system, by vapor compression stills, and the Multiple Effect (ME) distillation system, by multi stage stills.
The FIRST advantage of Vapor Compression is a higher energy efficiency
(low cost by quantity produced) (see our related site: vapor-compression-distiller.com).
The FIRST advantage of Multiple Effect distillation is less moving parts
(with lower maintenance requirement).