Discovering Desiccants

Posted in: General Information 25th March 2019

We've all seen the silica gel sachets thrown in the box of a new pair of shoes. But did you know that desiccant tablets and sachets are used to control the moisture and humidity inside packaging, particularly for pharmaceutical products? Here, Oliver Pittock, managing director at medical packaging experts, Valley Northern, explains the importance of desiccants and how it keeps our medicine safe.

You might think that the silica gel sachets that you find in a box of new shoes or tucked away in a pocket in a new handbag are meaningless. But these small sachets are actually vitally important, particularly when it comes to protecting pharmaceutical and medical products from moisture and humidity.

Moisture is one of the most damaging factors that can affect pharmaceuticals, both in drug production as well as in transit and storage. Moisture that is retained in medication packaging or containers can cause a lot of problems, including degradation of active substances, reduction of drug potency and the development of mould and mildew.


Desiccant formulas

Desiccants come in a variety of forms. The most common types used in pharmaceutical management is silica gel and molecular sieve.

Silica gel was initially patented in 1919 but was used widely during World War II for dehydrating pharmaceutical supplies. Silica gel uses hygroscopic salts, such as calcium chloride and perchlorates and can absorb up to 40 per cent of its weight, without increasing in size.

Silica gel is also available in two types, a white, non-indicating version and a second that changes colour when moisture is absorbed. The colour changing version is clearly incredibly useful, particularly in the pharmaceutical industry that may have shipments in transit or stored for long periods of time, as it indicates when the desiccant has stopped working.

A molecular sieve is a material with pores that can reduce moisture levels to almost zero. Molecular sieve products are used in applications where moisture needs to be completely removed.


Safety first

Despite not being toxic, non-indicative silica gel could cause irritation to the throat and nose if ingested and can be considered a breathing and choking hazard. Indicative silica gel, which can sometimes contain toxic additions such as methyl violet or cobalt dichloride are considered a substance of very high concern (SVHC).

As a result, it is important to use silica gel that meets international standards. Many suppliers, like Valley Northern, offer Food and Drug Administration (FDA) approved silica gel sachets.

Some organisations prefer to use desiccant canisters or capsules, which can not only absorb the moisture but also absorb odour. The canisters often also feature welded end caps, which mean they can prevent dirt and dust from encroaching the bottle or container and contaminating the contents.

So, don’t just dismiss the importance of those small silica packets when you next open a new box of shoes or pharmaceutical products in your pharmacy store room. They may be small and inconspicuous, but they are protecting the contents from potential ruin. 

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