What is a Generic Medication?
Before generic medicines we had ‘originator’ products which are medicines that are new and have been approved for marketing in Australia
Once the patent expires, ‘generic’ products can be marketed
A generic product is a medicine that, in comparison to the originator product:
Has the same quantitative composition of therapeutically active substances
Has the same pharmaceutical form
Is bioequivalent
Have the same safety and efficacy properties
What is Biological Medicine?
A medicine derived from a living system that may be either sourced from nature or produced using recombinant techniques
What are Biosimilars?
A biological medicine that contains a version of the active substance of an already authorised original biologic (reference product [originator]) that is similar in terms of quality, biological activity, tolerability and efficacy
Although highly similar, not identical versions of an already registered biological medicine
Why can’t we make exact copies of the proteins that are used as biological agent drugs?
Complex structures
What are Glycoproteins?
Protein with a sugar attached
What does Glycosylation affect?
Solubility, stability (susceptibility to proteolysis), antigenicity and orientation (structure of protein)
What are the 2 Categories of Glycoproteins?
N-Glycans
O-Glycosylation
Categories of Glycoproteins: What are N-glycans?
Covalently attached to proteins at the amide of asparagine
Categories of Glycoproteins: What is O-glycosylation?
Glycan is attached to the side chains of serine or threonine residues
Where does Glycosylation Occur?
Glycosylation occurs in endoplasmic reticulum and golgi apparatus - regulated by >200 enzymes
Most monoclonal antibodies are ____ sub-types?
IgG
What is the Molecular Weight of IgG?
150kDa
How many Amino Acids does IgG contain?
Contains over 1300 amino acids
How many Amino Acid Chains make up a single IgG molecule?
4 individual amino acid chains that make up a single IgG molecules
2 heavy chains (50kDa each) and 2 light chains (25 kDa each)
16 disulfide bridges
Heavy chain with one N-glycosylation site
Several O-glycosylation sites
What are Potential Problems with Biosimilars?
Altered biological activity
Changed pharmacokinetics
Altered stability
There is currently no system in place to determine formation of ADA prevalence (unregulated/unlimited switching from originator to biosimilar product) – can’t identify pattern of events
Brand substitution by pharmacists without reference to the prescriber is permitted for PBS prescriptions where?
The patient agrees to the substitution
The brands are identified as being interchangeable
The prescriber has not indicated on the prescription form that substitution is not to occur
Substitution is permitted under the relevant State or Territory legislation