One of the main differences between the individual medicinal products that we use to treat diseases and conditions lies in the size of their molecules. The group commonly known as small molecule products are produced through chemical synthesis, while the second group known as large molecule products (biologics) are produced through biological processes.
Molecules, as contained in the commonly used paracetamol and aspirin products, are considered small molecule entities and are stable compounds that are relatively easy to produce. In contrast, large molecule biologics (often used for chronic autoimmune conditions and in oncology) differ from chemically derived drugs in the following ways:
• Manufactured in living cell culture
• Unstable and sensitive to external conditions
• Complex in structure
Generally, biologic compounds are clinically very effective, but their complex nature results in more resources spent in research, development and manufacturing than the development of small chemical compounds. As a result, biologics are on average more costly to public and government funders than small chemical compounds.
In 2011 it was reported that in the United States, small molecule drug costs averaged US$1 (±R14.00) per day while biological treatment costs were on average US$22 per day (±R300.00).