lecture 5 - quality control and dosing

what to test for quality control for small chemicals?

• identity

• purity/impurities

• assay/content

• stability

identity

confirm its the correct protein

purity

detect contaminants and aggregates

potency

ensure biological activity

stability

check structural and functional integrity over time

sterility 

must be free of microbial growth 

goal of QC

to ensure protein drugs are safe, pure, potent, and consistent before patient use.

what is a unique QC consideration for protein drugs compared to small molecules?

confirming biological function through potency assays

purity testing in protein QC typically includes monitoring for

aggregates and host cell residues

A monoclonal antibody approved with a dose of 200 mg for all adult patients represents which dosing approach?

fixed/flat dose 

1. A monoclonal antibody is prescribed at 5 mg/kg. Patient weight = 70 kg. What is the dose in mg for this patient? (Note: Round your answer to the nearest whole number and include units with your answer, e.g, 1 mg or 1mg) 

350 mg

1. A patient requires 0.5 IU/kg of a clotting factor. Patient weight = 60 kg. The vial strength = 500 IU/vial How many vials are needed? 

1 vial

1. A patient requires 0.8 IU/kg/day of insulin lispro. Patient weight = 75 kg. Insulin concentration = 100 IU/mL. How many mL should the patient receive per day? (Note: Round your answer to the nearest tenth and include units with your answer, e.g., 0.1 mL or 0.1mL)

0.6 mL

small changes in QC of protein drugs can have a big impact on 

• potency 

• immunogenecity 

• safety 

the FDA

does not have specific guidance for QC of all proteins, instead the manufacturers must follow a set of comprehensive regulations

QC testing: identity and structure

• confirms the product is the right protein

• peptide mapping: usp 1055 confirms the primary amino acid sequence

• amino acid analysis: 1052 confirms overall amino acid composition

• mass spectometry: confirms the intact mass of the protein

• glycosylation: analyzing glycan structure as it can affect potency, half life, and immunogenicity

QC testing: purity

• measures the levels of process-related and product related impurities

• host cell proteins (1132): measures residual proteins from the host organism used in manufacturing

• size exclusion chromatography (129) asses the purity and identify aggregates or fragments

• ensures aseptic products have no growth

QC testing: potency 

• determines the biological activity or function of proteins 

• measures the drug’s intended therapeutic effect 

• protein determination procedures (507 and 1057) 

• common methods: lowry assay, bradford assay, and uv spectrophotometry 

QC testing: safety

• ensures the drug is free from contaminants like endotoxins and viruses

• bacterial endotoxin test (LAL) (85)

• sterility test (71)

• particulate matter (787)

factors that cause instability

• aggregation

• precipitation

• adsorption to vial walls

• deamidation

• oxidation

• hydrolysis

• disulfide scrambling

how to detect instability 

• HPLC (aggregate identification)

• fold confirmation: circular dichroism spectroscopy 

• bioassays to check for potency 

protein therap dosing

they require individualized dosing

why do protein drugs require individualized dosing?

• distribution depends on body weight, surface area, or metabolic rate

• immune reactions can alter half-life

• nonlinear PK due to receptor mediated clearance

dosing approaches

• fixed (flat) dose

• weight based

• activity based

• individualized dose

fixed (flat) dose 

same dose for all adults 

weight based dose

scales with the patient weight

activity based dose

based on biological unit (iu/kg)

individualized dose

adjusted via therapeutic monitoring

aggregates and host cell residues 

major purity concerns and unique to biologics

weight based and activity based dosing

standard for biologics

zinc, pH, and aggregation

affect insulin’s performance and stability