Stability and packaging Flashcards
State the main types of chemical instability
Photodegration
Oxidation
Isomerisation/polymerisation
Hydrolysis
Formation of adduct and complexes
Polymorphic changes
Temperature
What is stability?
“Stability of a pharmaceutical product is a relative concept that is dependant on the inherent stability if the active substance, excipients and dosage form, plus the protectiveness of the container closure system and the recommended storage conditions.” Pharmaceutics 5th edition (Aulton & Taylor)
What issues are linked with stability?
Issues linked to:
The API.
The excipients.
The processing to make a medicine.
The packaging.
The storage conditions.
What are the main types of physical instability?
Appearance
precipitation/ particle size
Rheology
Water content
pH
SDF - tablet strength and dissolution
Suspension - redispersibility/resuspension
Other than physical and chemical instabilities what other instabilities are there?
Packaging related - adsorption, absorption, leaching
Microbiological
Incorrect storage of use
What are processing instabilities for SDFs only?
Oxidation
movement of particles in mixing.
movement of particles in granulation
Hydrolysis
use of aqueous granulating solution and extensive mixing
Relative Humidity of the air.
Thermal Instabilities
Drying of granulation
Generation of heat in compression
Use of heat in the coating process
Melting of suppository components
How can you avoid instabilities for SDFs?
IDENTIFY CAUSE
Air (oxidation)
Water (hydrolysis)
Thermal degradation
Light degradation
REMOVE CAUSE
Use nitrogen blanket over process
Avoid granulation
Remove the need for using heat
Determine problematic wavelengths and use special light fitting without the offending wavelength.
REDUCE EFFECT
Add anti-oxidants to formulation
Reduce water content in granulating solution
Dehumidify the environment
Use lower temperatures (non-aqueous granulation).
Minimise the length of time the materials are handled in the presence of light.
How do you overcome chemical instabilities for hydrolysis with liquid and semi-solid dosage forms?
form a complex
drug with appropriate solubility, but with enhanced stability.
Modify chemical structure
attach appropriate substituent groups to improve stability. Must ensure therapeutic effect is not affected.
Solubilise drug within molecules
Make an emulsion
How do you overcome chemical instabilities for oxidation with liquid and semi-solid dosage forms?
Removal of oxygen by
Using well filled containers.
Boiling water immediately before use.
Use of inert gases to displace air above the product.
protection from light
Energy from light can be used to power the oxidation process.
Packaging methods are used to protect from light.
Wraparound labels
Cartons
Opaque containers
Light resistant containers.
UV resistant films on clear glass containers.
pH control
oxidation produces hydrogen ions.
An acidic pH will help prevent oxidation
(pH 3 – 4).
Solubilisation
oxygen is less soluble in a oily component than in an aqueous.
So dissolving the drug in an oil to produce an emulsion will protect it from oxidation.
How do you overcome chemical instabilities for microbial spoilage with liquid and semi-solid dosage forms?
Include preservatives to prevent growth once product is in use.
Manufacture in a suitable environment.
Parabens and phenoxyethanol.
What are some packaging instabilities?
The drug is not sufficiently protected by the packaging.
Resistant to the ingress of air or moisture.
Sufficiently opaque for a photosensitive product.
Not sufficiently robust to prevent physical damage.
The packaging has materials which could leach out into the product.
Tends to be a problem with liquid products.
Contents of liquid filled capsules could interact with the gelatine.
Suppositories made using fatty bases could absorb components from the plastic packaging.
How is stability testing tested?
Performulation Studies
Stress testing (short time, high temps, high humidity) drug only. Looking for likely drug degradation pathways.
Binary Mixes
1:1 ratio of drug and excipients.
Tested at high temp or using DSC.
Can have tertiary mixtures.
Formulation and container development
Multiple times on various formulation.
Actual storage conditions, time and testing regime dependant on formulation
Post-authorisation studies
To support licencing applications (at least 3 batches, at least 1/10th of full scale, both actual time and accelerated conditions).
Also GMP studies ongoing for a proportional number of batches of product throughout full shelf-life.
What are the reasons for packaging?
Product identity
Protect product
patient compliance
Presentation of information
Tamper protection and child resistance
Patient loyalty
What primary packs are available for liquids?
Glass
Good protection from moisture if hermetically sealed.
Clear or amber glass - light protection afforded when using amber glass.
Round, classic metric bottle or fluted.
Three main types of glass. (type I, II or III)
Aluminium bottles
same moisture protection as glass, better light protection.
Internal surface must be lacquered to prevent interactions.
Not common in UK – more often in US.
Plastics
polyethylene terephtalate (PET), polyvinyl chloride (PVC), polypropylene, polyethylene, polyethers and their derivatives.
Opaque plastic bottles provide some light protection, but not as good as amber glass or metal containers.
Moisture protection dependant on polymer used.
What primary packs have you got for semi-solids?
Glass - jars only
only used when materials would react with plastics or as a marketing tool in cosmetics.
Used for dispensing of extemp preparations.
Plastic - both jars and tubes
As on previous slide.
Extensive testing required to ensure no incompatibilities are present.
Metal - both jars and tubes
Extruded aluminium used.
Lacquered internal surface
Plastic and aluminium composites - most common
What are the additional requirements for bottles?
Cap standard screw cap, ratchet style (child resistant) or tamper-evident (tear-off section or break-seal type).
Foil - tamper-evident seal
SHrink sleeve - tamper-evident
Ullage take up - (inserts to take up additional space in bottles).
What sealing methods are there?
Bottles and jars – screw caps or push on lids.
May have tamper evident seals attached to the neck (paper with plastic and foil).
Tubes have a number of closing options.
Aluminium tubes – single fold, double fold or saddle back fold.
Plastic and composite (metal & plastic) – heat sealed
Ampoules are heat sealed and vials have rubber seals with aluminium safety caps