Drug stability refers to the ability of a drug product to retain its properties over time. There are several types of stability, including physical, chemical, and microbiological stability. Chemical stability can be impacted by degradation pathways like oxidation, hydrolysis, and decarboxylation. Photodegradation from sunlight can also impact stability, leading to discoloration or loss of properties, so photostabilization techniques are used. Accelerated stability studies subject drug preparations to high stresses like heat, humidity, and light to rapidly predict a product's shelf life.

1. Drug Stability
By
Kiran C. Rodge
Shivlingeshwar college of Pharmacy, Almala,
Tq-Ausa,Dist-Latur,Maharashtra

2. Definition of Stability
 Time lapse during which the drug product retains the same
properties that it possessed at the time of manufacture.

3. Significance of stability
• To study chemical Degradation
• During Decomposition
• To study Physical Degradation

4. Types of Stability
• Physical stability
• Chemical Stability
• Microbiological Stability
• Therapeutic Stability
• Toxicological Stability

5. Physical stability
Degradation pathways
1) Loss Of water
2) Absorption Of water
3) Loss Of Volatile Constituents
4) Crystal Growth
5) Polymorphism
6) Colour Changes

6. Chemical stability
Degradation pathways
1) Oxidation
2) Hydrolysis
3) Decarboxylation
4) Isomerism
5) Epimerization
6) Polymerization

7. Oxidation

8. Oxidation

10. Hydrolysis

12. Decarboxylation

13. Isomerism

14. Epimerization

15. Polymerization

16. Photodegradation
Photodegradation is degradation of a photodegradable
molecule caused by the absorption of photons, particularly
those wavelengths found in sunlight, such as infrared radiation,
visible light, and ultraviolet light.

17. Effects of Photodegradation & Need
for Photostabilization
 Loss in physical properties
 Discolouration
Hence in order to avoid such problems in the service
life of any product we give Photostabilization effect to
the polymer.

18. Photostabilization
Photostabilization is the retardation or elimination of the
Photodegradation of any polymer.
Stabilizers are classified as:
 Light screeners
 UV absorbers
 Excited state quenchers
 Peroxide decomposers
 Radical scavengers

19. Accelerated Stability Studies
Accelerated Stability Studies Stability study to predict the shelf
life of the product, by accelerating the rate of decomposition,
preferably by increasing the temperature of reaction conditions.
With the advancement in branch of kinetics, shelf life of a
dosage form can be predicted within months based on
accelerated stability reports
Preparations are subjected to high stresses during stability
testing.
Common high stresses include :
 Temperature
 Humidity
 Light