Elastomeric Pharmaceutical Stoppers Gamma Irradiation Resistance
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Solution Overview
Problem
Pharmaceutical stoppers and seals made from conventional elastomers are vulnerable to deterioration during gamma irradiation sterilization, leading to changes in physical properties such as hardness, compression set, and tensile strength, which can impact their performance.
Innovation Solution
Development of elastomeric polymers and compounded elastomers with reduced leachables and improved resistance to gamma irradiation, specifically using a method involving a mixture of C4 to C7 isoolefin monomers, styrene-based monomers, and optionally C4 to C14 multiolefin monomers, with 5 to 15 wt% styrene-derived units, that maintain their physical performances after gamma irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional elastomers are used for pharmaceutical stoppers, then good sealing and needle penetrability are achieved, but the material deteriorates during gamma irradiation sterilization leading to changes in physical properties
Solution Approach 1:
The patent changes the chemical composition parameters of the elastomer by incorporating specific amounts of styrene (5-15 wt%) and halogenated styrene (0.1-5 wt%) units into the polymer chain. This compositional modification enables the material to maintain dimensional stability and physical properties after gamma irradiation while retaining good sealing and needle penetrability characteristics.
Solution Approach 2:
The patent creates a composite elastomeric material by combining isobutylene polymer backbone with styrene and halogenated styrene comonomers. This composite structure integrates the advantages of different monomer units: isobutylene provides gas barrier and elasticity, while styrene units provide gamma irradiation resistance and dimensional stability.
2Object-generated harmful factors
If halobutyl polymers are used to improve gas and moisture barrier, then extractable and leachable levels are reduced, but the material remains vulnerable to gamma irradiation deterioration
Solution Approach 1:
The patent modifies the chemical structure parameters by introducing styrene and halogenated styrene units into the halobutyl polymer chain. This structural change maintains the low extractable and leachable characteristics of halobutyl while adding gamma irradiation resistance, allowing the material to withstand sterilization without significant property changes.
3Object-generated harmful factors
If BIMSM elastomer is used to achieve high cleanliness and drug compatibility, then oxidation and heat resistance are improved, but the material lacks sufficient gamma irradiation resistance
Solution Approach 1:
The patent adjusts the compositional parameters of BIMSM elastomer by optimizing the ratio of isobutylene to styrene units and incorporating halogenated styrene. This parameter optimization enhances the polymer's resistance to gamma irradiation-induced chain scission and crosslinking, improving dimensional stability while maintaining the inherent cleanliness and drug compatibility of BIMSM.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The described method ensures that the elastomeric pharmaceutical articles retain at least 80% of their original tensile strength and 100% modulus after gamma irradiation, providing improved stability and performance for pharmaceutical stopper and seal applications.
Implementation Method 1
subjecting the elastomeric compound to gamma irradiation
Implementation Method 2
an x-ray machine doses the material with ionizing energy. In gamma irradiation, Cobalt-60 or Cobalt-137 isotopes are used to generate a radiation source
Data Source
AI summary
Elastomeric polymers and compounded elastomers having reduced amounts of leachables and improved resistance to γ-irradiation sterilization suitable for pharmaceutical stopper and seal applications. These polymers and compounded elastomers maintain their physical performances upon being exposed to γ-irradiation over time and typical use conditions. The polymer is prepared by reacting a mixture of i) a C4 to C7 isoolefin monomer, ii) a styrene based monomer, and optionally iii) a C4 to C14 multiolefin monomer wherein the polymer contains 5 to 15 wt % of styrene derived units.