Water for medical use refers to purified water specially processed to meet strict quality standards for medical and pharmaceutical applications. It is used as a solvent, diluent, or cleaning agent in medical devices, laboratory procedures, and pharmaceutical formulations. Its production ensures sterility, absence of contaminants, and compliance with regulatory standards such as those set by pharmacopoeias (e.g., USP, EP, JP).

Chemical Composition and Structure

• Chemical Formula: H₂O
• Purity: Free from pyrogens, microorganisms, ions, organic impurities, and particulates.
• pH: Typically neutral (6.5–7.5).

The structure and chemical properties of water (polar molecule with hydrogen bonding) make it an ideal universal solvent, allowing it to dissolve a wide range of substances for medical applications.

Types of Water for Medical Use

1. Purified Water (PW):

   • Non-sterile water used in cleaning equipment and preparation of some non-parenteral formulations.

2. Water for Injection (WFI):

   • Sterile water used for the preparation of injectable solutions. Free of pyrogens and suitable for parenteral use.

3. Sterile Water:

   • Water that has undergone sterilization, used directly in medical procedures or as a diluent for drugs.

4. Bacteriostatic Water:

   • Contains antimicrobial agents to prevent microbial growth, often used for multiple-dose vials.

Physicochemical Properties

• Appearance: Clear, colorless, and odorless liquid.
• Specific Conductivity: < 1.3 µS/cm at 25°C (for WFI).
• Total Organic Carbon (TOC): Strictly controlled to ensure absence of organic contaminants.
• Bacterial Endotoxins: < 0.25 EU/mL (for WFI).

Production Process

1. Pre-treatment:

   • Source water undergoes filtration and softening to remove large particulates, ions, and organic matter.

2. Purification:

   • Techniques include reverse osmosis (RO), deionization (DI), and ultrafiltration to eliminate dissolved ions and impurities.

3. Distillation:

   • Produces high-purity water (e.g., WFI) by removing pyrogens and volatile impurities.

4. Storage and Distribution:

   • Stored in sanitized stainless-steel tanks and circulated in closed systems to maintain sterility and prevent contamination.

Applications

Medical

1. Parenteral Use:

   • As a solvent or diluent in the preparation of injectable drugs and intravenous solutions.

2. Cleaning and Sterilization:

   • Used to rinse surgical instruments, clean wounds, and sterilize medical equipment.

3. Dialysis:

   • Essential in hemodialysis for the preparation of dialysate solutions.

Pharmaceutical

1. Formulations:

   • As a vehicle for the preparation of oral, topical, and injectable pharmaceutical products.

2. Laboratory Use:

   • Utilized in microbiological testing, reagent preparation, and analytical procedures.

Industrial

• In the production of medical devices and as a rinse in cleanroom environments.

Regulatory Standards

Water for medical use must comply with pharmacopoeial standards, such as:

1. United States Pharmacopeia (USP): Specifications for purified water, WFI, and sterile water.
2. European Pharmacopeia (EP): Defines microbiological limits and chemical purity.
3. Japanese Pharmacopeia (JP): Provides guidelines for pharmaceutical-grade water.

Additional standards may apply depending on regional regulations and specific medical applications.

Environmental and Safety Considerations

• Sustainability:

  • Production systems aim to minimize water wastage during purification processes.

• Safety Profile:

  • Non-toxic and hypoallergenic. Special attention is given to maintaining sterility to prevent microbial contamination in sensitive medical environments.

• Storage and Handling:

  • Must be stored in sterile, sealed containers. Systems are regularly validated to ensure compliance with sterility and purity standards.

Conclusion

Water for medical use is a critical component in medical and pharmaceutical industries, supporting the safe preparation and administration of drugs, devices, and procedures. Its rigorous production and strict compliance with quality standards ensure reliability and efficacy in healthcare applications.

References__________________________________________________________________________

Pontoriero G, Pozzoni P, Andrulli S, Locatelli F. The quality of dialysis water. Nephrol Dial Transplant. 2003 Aug;18 Suppl 7:vii21-5; discussion vii56. doi: 10.1093/ndt/gfg1074. 

Abstract. Introduction: Every week, haemodialysis patients are exposed to approximately 400 l of water used for the production of dialysis fluids which, albeit with the interposition of a semi-permeable artificial membrane, come into direct contact with the bloodstream. It is therefore clearly important to know and monitor the chemical and microbiological purity of dialysis water. Methods: In this review, we analyse the sources of chemical and microbiological water contamination, and the problems involved in water purification systems and modalities. We also analyse the compliance of dialysis units with the microbiological standards established by the most widely accepted guidelines relating to the quality of dialysis fluids. Results: The risk of chemical contamination is due mainly to the primary pollution of municipal water, whereas the most important microbiological problem is the control of bacterial growth in the water treatment and distribution system. Dialysis water treatment implies various levels of pre-treatment, a final purification module (which, in many cases, is reverse osmosis: RO) and a hydraulic circuit for the distribution of the purified water. RO-based treatment systems produce water of optimal chemical and microbial quality, and so dialysis units need to concentrate on maintaining this quality level in the long term by means of effective maintenance and disinfection strategies. The most widely accepted standards for water purity are those recommended by the Association for the Advancement of Medical Instrumentation and the European Pharmacopea, which respectively allow bacterial growth of <200 and <100 c.f.u./ml, and an endotoxin concentration of <2 and <0.25 IU/ml. However, a number of multicentre studies have reported that 7-35% of water samples have bacterial growth of >200 c.f.u./ml, and up to 44% have endotoxin levels of >5 IU/ml. Conclusions: The results of multicentre studies indicate that the microbial quality of dialysis fluids is still a too often neglected problem, particularly as there is evidence of a possible relationship between dialysis fluid contamination and long-term morbidity. The time has now come to take advantage of innovations in water treatment processes and improvements in dialysis machines in order to modify clinical practices and start improvement processes aimed at decreasing the risk of microbial contamination to the minimum, as it has already been successfully done in the case of chemical contamination.

Mabic S, Kano I. Impact of purified water quality on molecular biology experiments. Clin Chem Lab Med. 2003 Apr;41(4):486-91. doi: 10.1515/CCLM.2003.073.

Abstract. Purified water is a reagent used in a variety of molecular biology experiments, for sample and media preparation, in mobile phases of liquid chromatography techniques, and in rinsing steps. The combination of several technologies in water purification systems allows delivering high-purity water adapted to each application and technique. Through a series of examples, the importance of water quality on biotechnology experiments, such as single nucleotide polymorphism (SNP) analysis by denaturating HPLC, RNA preparation and PCR, is presented. Results obtained on DNA mutation and single nucleotide polymorphism analysis using the denaturating HPLC (DHPLC) technique highlight the benefits of organic removal by UV photooxidation process. Comparative gel electrophoresis data show that ultrafiltration is as efficient as diethylpyrocarbonate (DEPC) treatment for suppressing RNase activity in water. Gel electrophoresis and densitometry measurement also point out the benefits of ultrafiltration to carry out reverse transcriptase-polymerase chain reaction quantitatively.

Anindita De, Singh NB, Guin M, Barthwal S. Water Purification by Green Synthesized Nanomaterials. Curr Pharm Biotechnol. 2023;24(1):101-117. doi: 10.2174/1389201023666220507030548. PMID: 35524657.

Marius M, Vacher F, Bonnevay T. Comparison of bacterial endotoxin testing methods in purified pharmaceutical water matrices. Biologicals. 2020 Sep;67:49-55. doi: 10.1016/j.biologicals.2020.07.001. Epub 2020 Aug 2. PMID: 32753293.

Tsompou A, Kocherbitov V. The effects of water purity on removal of hydrophobic substances from solid surfaces without surfactants. J Colloid Interface Sci. 2022 Feb 15;608(Pt 2):1929-1941. doi: 10.1016/j.jcis.2021.10.040.