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What is the Relequa System?
 A unique analysis tool for moisture profiling
 Gives „new information‟ on moisture interactions
 Very sensitive
 Suitable for tablets, powders, ointments and gels
 Uses and determines Equilibrium Relative Humidity (ERH)
What is ERH?
A Brief History
 1957 – First described for microbial growth in food
 Built into US CFRs for microbial safety in food
 USP <1112>: Application of Water Activity Determination to Nonsterile Pharmaceutical Products
What is ERH?
More Recently:
 EP 2.9.39 “Water-Solid Interaction: Determination of SorptionDesorption Isotherms and of Water Activity
 Published April 2011
What is ERH?
“Equilibrium Relative Humidity”
The %RH of the air surrounding a
material at the equilibrium point of
moisture absorption/desorption
ERH Measurement
Measurement Process:
 Material is placed in a sealed, controlled vessel
 Material will then reach its ERH with in that environment
 System continuously monitors the conditions within vessel
 Data logging software records the change and speed of change
of %RH in the vessel
Relequa Applications
Humidity and Drugs
 Most drugs either have instant absorption or desorption of
moisture
 Moisture causes physical and chemical damage to the drug
 Packaging and storage can act as a protective barrier to protect
drug
 Moisture activity can occur at various different points during
drug development and production
Relequa Applications
Analytical Methods
Karl Fischer – Moisture Content Assay
 Powdered sample used for analysis
 Tablet or sample may require grinding before analysis
 Powder may absorb or release moisture during process
 Activity will lead to errors in Karl Fischer moisture measurement
Relequa Applications
Analytical Methods
Relequa Applications
ERH and Crystallinity
 Water vapour movement is driven by ERH
 Molecules of water at surface of materials affects ratio of
amorphous to crystalline regions
Relequa Applications
ERH and Crystallinity
From:
The Use of material
Generated Moisture
Profiling to Probe
Physical Form Change.
AAPS 2010, Seymour,
Forbes & Hulse, BFG,
Univ. Of Bradford
Relequa Applications
ERH and Crystallinity
From:
The Use of material
Generated Moisture
Profiling to Probe
Physical Form Change.
AAPS 2010, Seymour,
Forbes & Hulse, BFG,
Univ. Of Bradford
Relequa Applications
Stability Testing
Moisture release from stability samples
Relequa Applications
Conditioning – Effects on Stored Product
Relequa Working Model
ERH Model
External
%RH
Container
Wall
ERH
Vapour Pressure
Internal
%RH
Material
ERH
Relequa Working Model
ERH Model
External
%RH
Container
Wall
ERH
Vapour Pressure
Internal
%RH
Capsule
Shell
ERH
Powder
ERH
Relequa Summary
Relequa ERH Analyser
 Instant results
 Shows changes in the substance/product
 Non-destructive
 Empirical – Actual environmental conditions
 Save time and cost
The Future……
Relequa ERH Analyser & Elite Enclosures
Temperature plays a huge part in %RH
From:
Dr Peter Moir,
Tablets & Capsules, May 2007
The Future…...
Relequa ERH Analyser & Elite Enclosures
Questions or queries to ask yourself:
 The Relequa system monitors the ERH based on
environmental conditions of the chamber (lab conditions)
the
 If my drug is being used in differing climates, how can I be sure
my drug wont react differently to differing environmental
conditions?
 How can I ensure repeatability of results where ever and when
ever a test is done?
The Future…..
Relequa ERH Analyser & Elite Enclosures
Answer:
MODIFY OR FIX THE ENVIRONMENTAL
CONDITIONS
The Future…..
Relequa ERH Analyser & Elite Enclosures
Place the Relequa system inside a temperature and humidity
controlled enclosure
Thank you for your time
If you have any question then please contact us:
Mr Neil Gwinnutt
Elite Measurement Solutions
Tel: 01908 506819
Email: neilg@elitemeasurement.com