Planning Stability Studies During
Product Development,
Subcontracting
Bob Seevers, Ph.D.
The Role of Stability in Drug
Development
• Stability studies play a central role in drug
development
• Permit understanding of the molecule
• Essential for developing analytical methods
• Essential for selecting packaging for drug
substance and drug product
• Essential for choosing storage conditions for
drug substance and drug product
The Role of Stress Testing
• Identification of degradation pathways
• Identification of degradants
• Determination of which type(s) of stress affect
the molecule
– Photostability
– High Temperature
– Low Temperature
– Oxidation
– pH extremes
Photostability
• Light can affect drugs, causing chemical changes
• ICH Q1B guidance spells out how to do photostability
tests
• Light sources
– Combination of visible and UV light
• Procedure
– Samples should be exposed to light providing an overall
illumination of not less than 1.2 million lux hours and an
integrated near ultraviolet energy of not less than 200 watt
hours/square meter
– Standards given identical exposure, but protected by light
barrier such as aluminum foil
Temperature Extremes
• Studies are typically done in increasing 10°C
increments (40°C, 50°C, 60°C, etc.) until
significant degradation is observed
• Freeze/Thaw studies
– Particularly important for proteins and other
biomolecules
– Example: insulin forms aggregates on freezing
Oxidation
• Typically done by placing the drug substance
in aqueous solution with hydrogen peroxide
• Goal is significant degradation
– Can identify degradants
– Determine whether protective packaging is
required
– Determine if an antioxidant should be considered
for the drug product formulation
pH Extremes
• Typically done by adding drug substance to
buffered aqueous solutions at pH values from 110.
• Can be complicated by limited solubility of the
drug substance under different pH conditions
• Again, the goal is significant degradation
– Determine degradants
– Decide if the molecule will survive passage through
the stomach
• Is enteric coating necessary?
• Should the drug be given by injection?
Degradation Reactions
• Oxidation
– Thiols (R-SH) form disulfides (R-SS-R)
– Alcohols (RCH2-OH) form aldehydes (RHC=O) and acids
(RC02H)
– Amines (R3N) can form amine oxides (R3N+–O-)
• Hydrolysis
– Usually caused by high or low pH
– Esters (RCO2R) form acids and alcohols (RC02H +
ROH)
– Amides (RCONHR) form acids and amines (RC02H +
RNH2)
Accelerated Stability
• Stability study run under more stressful
conditions than expected for long term
storage
• Different from stress studies in that the goal is
to get a quick understanding of what may be
expected from a long term study
Long-term conditions
Accelerated Conditions
Room temperature (25-30°C)
40°C/75%RH
Refrigerated (5°  3°C)
25°C/60%RH
Freezer (-20°C 5°C)
5°  3°C
Developing Analytical Methods
• Results of stress studies provide degradants
• These need to be identified and quantitated
• Selection of method
– Typically High Performance Liquid Chromatography (HPLC)
– Several types of solid phases available
• But it is essential to have some method available to
evaluate the results of stress studies
• Thus, stability studies and analytical method
development work together
– Start with drug substance molecule and separately
synthesized possible degradants to determine method
effectiveness
Methods Must be Stability-Indicating
• Analytical methods must effectively separate and
permit quantification of degradants
• Any significant changes in drug substance or drug
product quality over time must be detectable
– Increase in degradants
– Change in dissolution behavior
– Change in stereochemistry
• cis to trans or vice-versa
• optical isomers interconverting
How much stability data is needed?
• Pre-clinical
– Toxicology studies
– Analytical method development
– Stability of the drug substance in the form used for
testing must be demonstrated for the time frame of
the studies
• for tox studies this is typically a solution or suspension that
may be used for a period of days or weeks
• for analytical development this is usually a solution in the
solvent used to elute the column selected; such a solution
may be used for an extended period of time, if stable or
made fresh daily, if necessary
How much stability data is needed?
• Phase I
– Initial human studies
– Goal is to understand how well the drug is
absorbed in vivo and determine whether it is
reaching the selected target
– Studies may begin with only a small amount of
stability data for the drug substance and limited or
no stability data for the drug product
– If the drug substance is not stable, then more data
are needed as well as drug product data
How much stability data is needed?
• Phase II
– Goal is to determine dosing and get a limited sense of the
effectiveness of the drug
– By this point in drug development there is usually more
stability data available for the drug substance
– New routes of synthesis of the drug substance can lead to
different patterns of change on stability due to the
presence of different impurities, especially metals
– Stability data for the drug product in a formulation that
should be the same or close to the intended commercial
formulation is obtained
– Stability is obtained concurrently with clinical studies
– Failures on stability must be investigated promptly and
appropriate action taken, possibly including recalling the
drug from clinical sites.
How much stability data is needed?
• Phase III
– Large clinical studies to demonstrate the drug’s
safety and effectiveness
– Registration stability is typically done during this
time
• Final route of synthesis for drug substance
• Final formulation for drug product
• Final packaging for drug substance and drug product
How much stability data is needed?
• At the time of Marketing Application
Submission
– ICH Q1A and WHO guidance recommend a
minimum of 12 months long-term stability and 6
months accelerated
– This is a requirement in Europe
– This is negotiable in the US
– Expectations in other countries are similar
Drug Product Stress Studies
• Extreme temperatures
– determines whether excipients in the drug product
formulation will react with the drug substance
– key to dealing with temperature excursions experienced by
the drug product during distribution
• Freeze/thaw
– important if the drug product is at risk for experiencing
temperatures <0°C
• Shock and Vibration
– all products will undergo some amount of shock and
vibration in the distribution process; how will this affect
their quality
Determining Shelf-Life for Clinical Trials
• Phase I
– Shelf-life is typically extrapolated based on limited
stability data for the drug substance
– In cases where the drug substance shows
significant change, then drug product stability is
required before human studies begin
Determining Shelf-Life for Clinical Trials
• Phase II and Phase III
– Shelf-life is based on stability from previous work
and ongoing studies on current formulation
– Longer shelf-lives are generally needed due to
more extensive clinical studies
– Stability studies are done concurrently with
clinical studies
– Shelf-life can be extended as more stability data is
obtained
Registration Stability Studies
• Information from ICH Q1A and WHO guidances
Long-term conditions
Stability Conditions
Room temperature (25-30°C)
25°C/60%RH or 30°C/65%RH or 75%RH
Refrigerated (5°  3°C)
5°  3°C
Freezer (-20°C 5°C)
-20°C 5°C
• Intermediate conditions: 30°C/75%RH if 25°C
used for long-term and significant change
occurs
Selection of Long Term Stability Conditions
• ICH Q1F attempted to define a single long
term condition for all countries in climatic
zone IV (hot and humid) of 30°C/65%RH
• This was not acceptable to all countries and
Q1F was withdrawn
• WHO has asked countries to choose between
30°C/65%RH and 30°C/75%RH
• WHO 2009 guidance lists 200 countries and
their choice or WHO’s best estimate
Selection of Long Term Stability Conditions
• Practical implications of the complex Zone IV
situation
• Most drug companies do their first registration in the
US and Europe: Zone II countries with 25°C/60%RH
stability data
• Since generation of both 30°C/65%RH and
30°C/75%RH stability data is a double expense a
choice must be made
• Since all Zone IV countries will accept 30°C/65%RH
data, this has become the default
Stability of Comparators
• Comparators are used in clinical trials to test the new
drug against standard therapy
• For a blinded trial, the comparator must be disguised,
typically by overencapsulation
• The blinded comparator must be studied on stability
– Dissolution
– Degradation
• If compendial methods are not available, tests must be
developed
• Shelf-life for comparator cannot exceed manufacturer’s
expiration date
Stability of Placebos
• Placebos must be evaluated on stability
• Appearance is the only attribute that needs to
be tested
• If the appearance changes over time, the
blinding of a study may be broken
• Placebos can be given a long shelf-life based
on available data; if the color doesn’t change
over 12 months, it is not likely to change over
36 months
Subcontracting Stability Studies
• This is often done to firms that can provide
services
– Stress Testing
– Analytical development
– Stability chamber storage
– Stability testing
• It is essential to ensure that data from the
contract lab is reliable
Auditing Stability Labs
• Check their Quality Systems
– Organization and Personnel
– Laboratory Controls
– Production and Process Controls
– Buildings and Facilities
– Material Handling
– Records, Reports, and Documentation
• Create a Quality Agreement that clearly spells
out expectations on both sides
Summary
• Stability studies play a central role in drug
development
– Permit understanding of the molecule
– Essential for developing analytical methods,
selecting packaging and storage conditions for
drug substance and drug product
• Stability data submitted to Health Authorities
to support registration must be reliable