Blister Packaging Testing Methods

Introduction

Blister packaging or press through packaging (PTP) is a widely used packaging technique in the pharmaceuticals industry, especially for the mechanized packaging of solid medicines. It represents 30% of the worldwide market for pharmaceutical packaging. The following are the key benefits of blister packaging:

Allows medicine to be stored in stable and reliable condition

Facilitates minor amount and serial packaging

Provides convenient, portable, hygienic, and safe packaging

More versatile and allows for long-term storage

Features functions such as counter forgery and identification

Testing Specifications for Blister Packaging

Blister packaging is mainly used for solid drugs, preventing the drugs from exposure to microorganism, foreign matter, moisture, and air and avoiding the leakage, release, or evaporation of the APIs present in the drugs.

Material testing is essential due to the possibility of the direct contact of the drugs with blister packaging materials such as PVC/PVDC laminated sheets, PVC sheets, and PTP aluminum foil. The testing parameters include barrier property, appearance, hygiene indexes, and mechanical properties such as impact resistance strength, tensile strength, thermal tensile ratio and much more. This article discusses the testing of key characteristics of blister packages.

Barrier Property Testing

Barrier property testing includes testing of oxygen transmission rate and water vapor transmission rate. The testing procedure for oxygen transmission rate in aluminum foil packaging is not described in the standards. However, if the number of pinholes meets the specifications outlined in the standards, it can be taken as a measure of the oxygen transmission rate requirement for a specific packaging. High precision instruments must be used for testing due to the high barrier properties of PVC and aluminum.

It is not possible to test the entire blister package on the current whole package testing fixtures, due to the small sizes of the package. The values obtained from the film barrier property testing significantly differ from the actual water vapor transmission rate and oxygen transmission rate of the packaging materials due to force of the aluminum foil, thermal tensile ratios of the materials, and the uniformity of the adhesives.

For that reason, a specially designed fixture is used for blister sample preparation to test the whole blister’s barrier property (Figure 1). Testing of rates of water vapor transmission and oxygen transmission is performed using sensor method and equal pressure method, respectively. The flow velocity is carefully adjusted during the testing to prevent the impact on the sample status caused by the change in the gas quantity and the subsequent change in the pressure inside the blister.