Degradation of Pharmaceutical Products II Flashcards
Dr. Cardoso
With a suitable example, explain photodegradation.
Photodegradation is the process by which a substance is chemically broken down or altered due to exposure to light, particularly ultraviolet (UV) light.
- Light can activate oxygen molecules, increasing the rate of oxidation.
- Or direct photodegradation can break bonds between molecules
Example: Retinol, Riboflavin, Nifedipine, Nicardipine, Chloroquine and Primaquine
Highlight the methods of preventing photodegradation of pharmaceuticals.
- Use opaque containers
- Use coloured containers: Yellowish-green glass is the best protector against UV.
- Addition of antioxidant e.g. Sodium metabisulphite
Why are metal containers rarely used.
Because they are highly reactive
The conventional method employed
to predict the propensity for dehydration uses _________, which is related to _______________.
dehydration temperature
How tightly water molecules are bound to the crystal lattice.
What is dehydration? Give 2 examples of drugs that undergo dehydration.
Dehydration is the elimination of a water molecule from a molecular structure.
Examples: Prostaglandin E2 and Tetracycline
[Equation?]
Other kinetic factors that affect dehydration behaviour are:
i. Intermolecular interactions
ii. Drug-substance-to-water molar ratio
How do you prevent dehydration?
Store in a cool place with regulated humidity.
What is isomerisation?
This is the conversion of a drug into its optical or geometric isomers, which have the same molecular formula, but different structural arrangements.
E.g. conversion of D-glucose-6-phospate to D-fructose-6-phosphate by phosphoglucoisomerase
What are the types of isomerism?
- Optical isomerism
- Geometric isomerism
With examples, explain the types of optical isomerism.
- Racemization: This is the conversion of a chiral molecule to a mixture of equal amounts of its enantiomers, known as a racemic mixture.
E.g. S-thalidomide helps with morning sickness, while R- thalidomide causes birth defects.
Atropine is a mixture of (-) and (+) hyoscyamine - Epimerization: Epimerization is a change in stereochemistry that occurs at one chiral center in a molecule that has more than one chiral center.
E.g. Under prolonged storage solution containing ergometrine is decomposed to ergometrinine
- Pilocarpine to Isopilocarpine
- Tetracycline to Epi-tetracycline
What is geometric isomerism? Give an example.
Geometric isomerism is a kind of stereoisomerism that occurs due to the restricted rotation about carbon-carbon double bonds or carbon-carbon single bonds in cyclic compounds.
E.g. Formation of cis- and trans- Vitamin A
How do you prevent isomerism?
- Avoid Basic Conditions for Carbohydrates
Mention 5 primary functions of packaging.
- Product identification
- Product promotion
- Product protection and stability
- Product instructions
- Ease of use
What is pharmaceutical packaging?
Pharmaceutical packaging is the science and technology of enclosing pharmaceutical products in suitable materials for protection, stability, identification, distribution, storage and therapeutic use.
What are the types of packaging?
i. Primary packaging: This is the material that first encloses the product, and has direct contact with the product. E.g. blister packs, bottles, plastics containers (screw cap). It is usually is the smallest unit for distribution.
ii. Secondary packaging: This is the intermediate packaging. It is used to group the primary packaging together e.g., cardboard boxes.
iii. Tertiary packaging: Used for bulk handling and shipping e.g. barrels, containers and cartons.
