Abstract: As blister packages for pharmaceutical drugs become more popular because of their many benefits, such as protecting drugs over long shelf-life, portability, and being tamper resistant. For shelf life, blister packaging provides a barrier protection against contamination, particularly water vapour and oxygen. To control the quality of blister packaging and identify proper shelf life of pharmaceutical drugs, we need have knowledge of permeability characteristics of blister packaging.

Keywords: Blister packaging, permeability characteristics, oxygen barrier property, water vapor barrier property, Labthink, oxygen transmission rate, water vapor transmission rate tester

Blister packaging plays an important role especially for oral- and solid-dosage forms because of their many benefits, such as portability, being tamper resistance, greater efficiency, cost reduction and protecting drugs over long shelf-life.

Pharmaceutical substances are getting more and more sophisticated, and also tend to get more and more sensitive to environmental influences like the attack of moisture and oxygen. The exposition of tablets and capsules to oxygen and/or moisture can have serious effects:

• Softening and disaggregation (mechanical corrosion)
• Chemical hydrolysis of the active ingredients (decrease of potency and/or forming of toxic compounds)
• Oxidation of the active ingredients (decrease of potency and/or forming of toxic compounds)
• Worst case, fatality can be the result of missing medication or decomposition of the product.

To avoid or reduce such negative influences, the drugs must be protected by an effective barrier packaging. The first step in finding blister packaging solutions is to find out what you need. Evaluate your product to see how much protection is necessary.

Water Vapor Transmission Rate

Water Vapor Transmission rate is a measure of the passage of water vapor through a membrane. It is the rate of water vapor transmission per unit area per unit of vapor pressure differential under test conditions. It is an index of the ability of materials barrier water vapor. Higher water vapor transmission rate, poorer water vapor barrier property, shorter shelf life of products

Oxygen Transmission rate

Oxygen Transmission Rate (OTR) is the steady state rate at which oxygen gas permeates through a film at specified conditions of temperature and relative humidity. Value is expressed in cc/100 in2/24 hr in US standard units and cc/m2/24 hrs. in metric (or SI) units. It usually depends on the type of material, pressure, temperature and thickness of materials. Same as water vapor transmission rate, oxygen transmission rate is also an index of the ability of materials barrier oxygen.

Water Vapor & Oxygen Transmission Rate Measurement

Before choosing your blister packaging materials or find blister packaging barrier solutions, you need to know what is the water vapor transmission rate (if the pharmaceutical drugs are sensitive to water vapor) and oxygen transmission rate (when drugs are sensitive against oxygen), then evaluate your product to see how much protection is necessary.

Oxygen Transmission Rate Testing Method

Current testing method for oxygen transmission rate is equal pressure method, also known as Coulometric method. Usually, there are two chambers in this testing method. One chamber contains oxygen or air and the other chamber is slowly purged by a stream of nitrogen. Due to the concentration difference between the two chambers, oxygen molecules permeate through the specimen into the nitrogen side and are taken to the coulometric sensor where it produces corresponding amount of electrical signals. The oxygen transmission rate is then obtained by analyzing and calculating the signals.

Water Vapor Transmission Rate Testing Method

Currently, there are several testing methods for water vapor transmission rate testing, such as cup method, infrared sensor method, humidity sensor method and electrolytic sensor method. The most used method is wet cup method described by ASTM E96. Under a certain test temperature and humidity difference, measuring the weight changes of the test dish in different time, water vapor transmission rate and other parameters can be obtained.

We recommended you Labthink water vapor transmission rate testers or oxygen transmission rate testers, they can give you an accurate testing data for your blister packaging materials or finished blister packages. You can get all the instruments based on different testing method according your requirement from Labthink. The company is famous with their professional and high accuracy in the testing industry. You can visit their website www.labthinkinternational.com.cn for more information