Page 17 - Drug Discovery and Development: Prospects and Challenges

cancer (USD 10.69 billion) products. At the time of this writing, the COVID-19 vaccine is being
developed by Johnson & Johnson using vector technology and it is scheduled for release in the first
quarter of 2021 for emergency use (Figure 4) (Pharmaceutical Technology, 2021). In terms of
individual drugs, Humira by Abvvie was the best-selling pharmaceutical drug in 2020 with USD 20.4
billion in sales. Approved in 2002 in the United States, Humira is a prescription drug that is used to
treat rheumatoid and psoriatic arthritis through subcutaneous injection. The drug is also used to treat
autoimmune diseases, such as Crohn's disease, ankylosing spondylitis, ulcerative colitis, psoriasis,
uveitis, and others. Besides Humira, the highest selling pharmaceutical products include Eliquis and
Revlimid, which are used to treat multiple chronic conditions or cancer (Figure 5) (Pharmaceutical
Technology, 2021).
60
50
40
30
20
10
0
GlaxoSmithKline
Johnson & Johnson Pfizer Roche Novartis Revenue (bn) Sanofi AbbVie Takeda Shanghai…
Merck & Co.

Drug Discovery and Development: Prospects and Challenges / 7
Figure 4: Top ten pharmaceutical companies with the highest revenue in 2020
Sales in billion U.S dollars
25
20
15
10
5
0
Keytruda (Merck & Co.)
Humira (Abbvie) Revlimid (BMS) Eylea (Bayer/Regeneron) Opdivo (BMS/Ono Pharm.) Imbruca (Abbvie) Biktarvy (Gilead)
Xarelto (Bayer/J&J)
Stelara (Janssen Biotech)
Eliquis (BMS/Pfizer)

Figure 5: The leading pharmaceutical product sales in 2020
Figure 5: The leading pharmaceutical product sales in 2020

Brothers and sisters,
Ladies and Gentlemen, 11
Source of Drugs
The available drugs in the market today are derived from various
sources, including natural, synthetic, biosynthetic, and recombinant
technology. The natural source of drugs includes those from plants,
animals, marines, and minerals, as well as microbiological sources.
Given its long history as an effective remedy for a variety of ailments,
plant-derived compounds have been used in the clinical setting with better
patient acceptance and tolerance. To date, about 35,000–70,000 plant
species have been tested for their medicinal use. In particular, plants that
possess ethnopharmacological properties have been the major sources
of medicine in the development of early drugs. According to Fabricant
and Farnsworth, 80% of the 122 plant-derived medicines are used for
ethnopharmacological purposes (Fabricant & Farnsworth, 2001).
When a new disease or clinical condition emerges and could not be
treated with any currently available medication, this trigger a motivation
to initiate a drug discovery project (Hughes et al., 2011). The early
stage of drug discovery begins with the ethnopharmacological approach
by random selection or chemotaxonomic approach (Figure 6). The
plant sample is obtained using conventional extraction methods, such
as maceration, percolation, soxhlet extraction, and non-conventional