Many diseases occur as a result of defects or errors in the genes involved in producing essential enzymes or proteins in the body. The genes are coded in deoxyribonucleic acid (DNA), helical double-stranded molecules folded into chromosomes in the nucleus of cells. The Human Genome Project was created several years ago to sequence the human genome. This national effort has generated information on the role of genetics in congenital defects, cancer, disorders involving the immune system, and other diseases that have a genetic link.
The emerging genetic basis of disease is providing novel opportunities for the development of biotechnology-derived pharmaceuticals (biopharmaceuticals) to treat specific disorders. The use of recombinant DNA (rDNA) technology and its application to new drug development has revolutionized the biopharmaceutical industry.
Presently, most drugs that are used to treat disease are small-molecular-weight, well-characterized molecules that are generally manufactured by chemical synthesis. In contrast, biotechnology-derived drugs are very large-molecular-weight drugs (eg, proteins) that have complex chemical structures. In some cases, there is limited ability to characterize the identity and structure of the biopharmaceutical and to measure the activity of the clinically active component(s) such as the specific active moiety. These biopharmaceuticals are often manufactured by fermentation, using recombinant DNA or other biosynthetic approaches in which the manufacturing process, original cell lines, and purification process can have an impact on quality, safety and efficacy of the drug.
These large biopharmaceuticals have enormous potential to treat disease in novel ways previously unavailable to small drug molecules. As a result, biotechnology, or the use of biological materials to create specific biopharmaceuticals, has become an important sector of the pharmaceutical industry and accounts for the fastest-growing class of new drugs in the market. Nucleic acid, protein and peptide drugs, and diagnostics are the main drug products emerging from the biopharmaceutical industry.
The human genome produces thousands of gene products that prevent disease and maintain health. Many of these gene products may have therapeutic applications if supplemented to normal or supraphysiologic levels in the body. Most of the biologic molecules listed in Table 18-1 are normally present in the body in small concentrations but are used for certain therapeutic indications. For example, some diseases such as insulin-dependent diabetes result from insufficient production of a natural product, in this case insulin. For these patients, the treatment is to supplement the patient's own insulin production with recombinant human insulin (eg, Humulin). Similarly, human recombinant growth hormone (Protropin, Nutropin) and glucocerebrocidase (Ceredase, Cerezyme) are used to treat growth hormone deficiency and Gaucher's disease, respectively.
Table 18-1 A Sample of Approved Recombinant Drugs |Favorite Table|Download (.pdf)
Table 18-1 A Sample of Approved Recombinant Drugs
|Drug||Indication||Pharmacokinetics||Year Introduced, Company (Trade Name)|
Renal cell carcinoma
Half-life = 85 min; Cl = 268 mL/min
1992 Chiron (Proleukin)
Acute myocardial infarction...