Technical Customer Support

September 13, 2013

A Comparison of Halobutyl Elastomers

When choosing an elastomeric formulation for a stopper or plunger used to package parenteral drug products, there are several misconceptions related to the importance the elastomer class plays on the chemical and physical properties of the elastomer. Often we hear customers make general statements such as “chlorobutyl elastomers are better” or “bromobutyls have an advantage in property X.” In actuality, each elastomeric formulation is unique and has different properties that are independent of the class of elastomer.
If one were to generalize, most halobutyls have strikingly similar moisture vapor and oxygen transmission rates, durometer, compression set and tensile strengths. Differences in elastomeric properties often depend more on the amount and type of fillers, plasticizers, curing agents and antioxidants than the particular species of halogen used in the base polymer.

When choosing an elastomer for a generic drug product, is it necessary to stay within the same elastomeric class as the innovator? Based on our experience, there is no advantage to maintaining the same class of elastomer as the innovator because physical and chemical differences are on a formulation-specific basis. There is no indication from regulatory bodies that speed to market can be increased by maintaining the innovator elastomeric class. We have found that regulatory bodies are much more concerned that the generic drug manufacturer has an understanding of their packaging components through scientific processes and data generation that show the chosen packaging does not affect the safety, purity and efficacy of the drug product.

Ultimately, it is important to select an elastomeric formulation that will meet the needs of your drug product and its end use. There is no one-size-fits-all formulation, so component selection must be made with the critical quality attributes that are most important to each unique application in mind.