Biopharmaceutical Exam Flashcards
What are three factors decreasing GI absorption of protein drugs?
- size limits epithelial permeability
- chemical hydrolysis
- enzymatic proteolysis
What are two factors affecting protein toxicity (safety)?
- dose-related pharmacological activity
2. off-target toxicity related to immunogenicity of protein
When does aggregation occur?
denaturing leads to exposed hydrophobic residues that can associate with other protein molecules
What are four (4) processes that can cause denaturation?
- temperature
- surface interaction
- agitation
- foaming
Name five (5) excipients used in biopharmaceuticals?
- Tween 80
- albumin
- sucrose
- EDTA
- TRIS
Why is Tween 80 used in biopharmaceuticals?
surfactant and stabilizer against aggregation
Why is albumin used in biopharmaceuticals?
protein and stabilizer against surface-mediated aggregation
Why is sucrose used in biopharmaceuticals?
diasaccharide used to stabilize lyophilized protein formulations
Why is EDTA used in biopharmaceuticals?
metal ion chelator used to protect against oxidative instability
Why is TRIS used in biopharmaceuticals?
buffer used to control pH
What is the major limitation of using prokaryotic cells for protein production rather than eukaryotic cells?
prokaryotic cells are incapable of post-translational protein modification (e.g. glycosylation)
Why are protein drug substances frozen?
Bulk protein drug substance are frozen to stabilize before final drug product formulation.
What are the pros and cons of freezing (frozen liquid) vs freeze-drying?
- Freezing is less time-consuming
- Freezing is less costly
- Freeze-drying provides greater stability.
What are two (2) reasons protein drug substanced are lyophilized [freeze-dried]
- protect against hydrolysis [chemical]
2. protect against physical instability from solutoin [physical]
List seven (7) sources of biopharmaceutical contamination
- particulates
- leachables
- bacteria
- mycoplasma
- virus
- pyrogens
- endotoxins
List the advantages and disadvantages of live attenuated vaccines
- adv: possibility of life-long immunity
2. disadv: revert to virulent form
List the advantages and disadvantages of inactivated (killed) vaccines
- adv: no risk of reversion
2. disadv: require booster administration and adjuvants
List five (5) types of vaccines
- subunit vaccine
- polysaccharide
- recombinant
- live-attenuated
- inactivated
List an example of a subunit vaccine
Pertussis
List two (2) examples of a polysaccharide vaccine
- streptococcal pneumonia
2. typhoid
List two (2) examples of a recombinant vaccine
- hepatitis B
2. HPV (papilloma)
List eighth (8) examples of live-attenuated vaccines
- oral polio
- measles
- mumps
- rubella
- influenza
- smallpox
- typhoid
- anthrax
List five (5) examples of inactivated vaccines
- cholera
- pertussis
- inactivated polio
- influenza
- hepatitis A
What is the antigen production host for a viral vaccine?
- Cell cultures
2. Eggs (chicken)
What is the antigen production host for a bacterial vaccine?
- bacterial fermentation
2. yeast fermentation
What are two (2) reasons adjuvants are used in vaccine formulations?
enhance immune response by:
- increasing antigen uptake
- inducing the production of cytokines and complements
What is thimerosal?
mercury-containing microbial preservative that has historically been used in vaccines
What are the safety concerns for thimerosal?
potential toxicity in children
From what vaccines was thimerosal removed?
Vaccines recommended for children – single-dose vaccines.
In what vaccines does thimerosal remain?
Multi-dose vaccines, including influenza.
What is the function of gelatin in vaccinations?
stabilize vaccine against physical instability
What are the safety concerns of gelatin?
one in 2 million children experience hypersensitivity reaction to gelatin
What three (3) amino acids are basic?
- Arginine
- Lysine
- Histidine
- terminal amines
What two (2) amino acids are acidic?
- Aspartic acid
- Glutamic acid
- terminal acids
What amino acids are susceptible to oxidation?
- Methionine
2. Cysteine
What amino acids are susceptible to carbonyl amine reactions (e.g. glycation)?
- Lysine
2. Terminal amines
What amino acids are susceptible to deamidation?
- asparagine
2. glutamine
How does a second structure in a region of “susceptible to degradation” affect rate of degradation?
Secondary structure decreases rate of degradation.
What is the primary structure?
Sequence of amino acids
What is secondary structure?
Alpha helices and Beta-sheets – amino acid configuration; weak interactions.
What is tertiary structure?
three dimensional globular sturcture, native and denatured conformations
What is quaternary structure?
intermolecular interactions such as aggregation and association (dimers, hexamers, polymers)
Describe the general trend of protein solubility?
Proteins tend to be ionized at extreme pH. There is a certain pH that is the “isoelectric point,” at which net charge is zero and solubility is at minimum.
What are three benefits of directions of use in protein pharmaceuticals?
- avoid aggregations/precipitations problems (temperature, surface interaction, foaming, agitations etc.)
- avoid chemical instability
- avoid incompatibilities
What are three (3) strategies for preventing proteins from degrading?
- refrigeration
- freeze-drying
- placing a nitrogen headspace over a drug in a tightly sealed container
What are four (4) examples of physical instability?
- insolubility
- foaming
- catastrophic aggregation
- gelation
Does dissolving a protein in D5W increase protein stability?
No.
