Moisture is unavoidable. It is in the air we breathe and the products around us. However, its presence, or lack thereof, in pharmaceutical products has a direct impact on the quality and, in some cases, the makeup of the products.
Measuring the amount of water within a particular product is difficult due to the complex intermolecular bonding properties that make up the substance matrix. Therefore samples are widely relied upon for moisture content analysis for all products; not just those within the pharmaceutical industry.
As water content will impact products differently, it must be monitored at every stage of the production and delivery process to ensure the quality of the products are not diminished and that the medicines act as they should.
What is water content in pharmaceuticals?
Water content, also known as moisture content, is a term associated with the amount of water held in a substance or material. In regards to the pharmaceutical industry, an in-depth understanding of the maximum moisture content allowable during the processes for each product is essential.
How does moisture content impact pharmaceuticals?
Moisture content impacts pharmaceuticals in a variety of different ways, depending on the ingredients and the form the medicine takes:
- Gel capsules: may dissolve under the presence of moisture
- Tablets, effervescent tablets, powders: the texture and properties may be impacted by moisture
- Urine or blood test strips: moisture present may result in misleading or false results
More broadly, moisture content can affect the quality and efficiency of the products, the shelf-life and usability. Therefore, moisture content must be carefully monitored.
Medicine that does not act in the way it is expected to has the potential to slow down recovery, with maximum consequences being life-threatening.
Improved method of water content analysis within the pharmaceutical industry
Measuring the water content of the raw ingredients is just as important as analysing the content held within the finished product. Methods of measuring water content within the pharmaceutical industry have mainly made use of Karl Fischer Titration and Loss-on-drying methods; however, a new technique was introduced in 2015.
Headspace Gas Chromatography
The Headspace Gas Chromatography measures volatile analytes. This method was suggested to work well on a wide range of pharmaceutical products, being more sensitive than other water content analysis methods.
Disadvantages of traditional methods included poor sensitivity and reproducibility, time-consumption and inability to be utilised on all products,
according to one of the authors of a paper related to the new method. He has stated that his new approach provides improved performance of the disadvantages mentioned.
In 2017, Gas Chromatography was positioned to challenge the Karl Fischer Titration method following the development of both new columns and detectors sensitive to water. The technique can be carried out with the headspace formats mentioned or via direct injection.
Preventing moisture in pharmaceutical packaging
In addition to measuring moisture levels throughout the manufacturing process, it is essential to continue measuring water content levels throughout the packaging and delivery process, as moisture within pharmaceutical packaging can also impact the products within. In addition to damaging the medicines, it can also produce an unpleasant odour which is off-putting to patients.
Approximately humidity ingress of roughly 65% can be attributed to pharmaceutical packaging. Weak spots such as the sealing surfaces and packaging walls must be considered when finding a solution to effective packaging that does not impact the quality of the products it holds.
Some solutions to packaging pharmaceuticals regarding moisture content control involves making use of:
- Molecular sieves or silica gels
- Drop-in sachets
- Activated carbon
- Desiccant capsules
These work to attract moisture, keeping it away from the products and simultaneously reducing odours stemming from moisture content within pharmaceutical packaging.
Whatever method is used to monitor the moisture content within pharmaceutical processes, it is crucial that analysis takes place during every stage, including the packaging process.