What pharmacies should know about USP standards

In retail pharmacy, the requisite water for use during reconstitution and non-sterile compounding has never been entirely clear.  While labels on medications for reconstitution will indicate a specified volume of water for reconstitution, the level of water quality required by a manufacturer is not clearly stated. Pharmacies and state boards of pharmacy typically rely on best practice standards published by USP and as specifically interpreted from USP 795 Nonsterile Compounding and USP 1231 Water for Pharmaceutical Purposes.

Until recently, standards for achieving USP 1231 pharmaceutical-grade water for special pharmaceutical purposes left much to interpretation. Water considered ideal drinking water by the  EPA and World Health Organization seemingly satisfied the definition of purified water as outlined on USP 1231.

But with the proposed revisions to USP 795 that have been published for comment, along with information provided by USP’s expert committee on water, we now have a very clearly defined standard for purified water to be used in non-sterile compounds and medications that require reconstitution.

The revision proposal, while not yet official, states: “Purified water, or an equivalent quality of water, must be used to reconstitute conventionally manufactured nonsterile products when water quality is not stated in the manufacturer’s labeling.”

Given these parameters, there are three suitable methods to consistently meet the USP standard for purified water for reconstitution and nonsterile compounding — reverse osmosis water filtration systems with stand-alone deionizing and antibacterial filters; sterile, enclosed pharmaceutical-
grade bottled or bagged water; and Vapor distillation systems.

While each of these methods has its benefits and drawbacks, a reverse osmosis system is the most cost-effective and easy-to-maintain system to employ in retail pharmacy. The cost per milliliter of water dispensed with a reverse osmosis system is a fraction of what it costs to use and maintain sterilized bottled/bagged water or a vapor distillation system. Also, a standard 4- or 5-stage reverse osmosis system, without a standalone deionizing filter, will struggle to maintain acceptable conductivity levels over time.

How seriously should retail pharmacy take USP standards for water quality when it comes to non-sterile compounding and reconstitution? Will state boards of pharmacy begin requiring testing of water quality during routine inspections? That remains to be seen. Standards are developed based on knowledge centered on the best science available at the time and expertise from academicians, healthcare professionals, healthcare industry and other stakeholders.  USP, the FDA, and boards of pharmacy collectively have said their top priorities revolve around standardization and ensuring public health. The hope and promise of standardization is striking a balance between quality and safety, without overregulating or underregulating, and maintaining reasonable cost and accessibility to the patient.

As pharmacies navigate and understand the ever-changing regulatory landscape, they must be sure the products and services they offer to their customers evolve as well. Complying with USP’s purified water guidelines means pharmacies from every part of the country dispense a uniform product, irrespective of their water supply.

Ursula Chizhik is vice president of quality and regulatory affairs at FlavoRx.