The local investigators are responsible for conducting the study according to the study protocol, and supervising the study staff throughout the duration of the study. The local investigator or his/her study staff are also responsible for ensuring the potential subjects in the study understand the risks and potential benefits of participating in the study; in other words, they (or their legally authorized representatives) must give truly informed consent. They are responsible for reviewing all adverse event reports sent by the sponsor. (These adverse event reports contain the opinion of both the investigator at the site where the adverse event occurred, and the sponsor, regarding the relationship of the adverse event to the study treatments). They also are responsible for making an independent judgment of these reports, and promptly informing the local IRB of all serious and study treatment-related adverse events.

Protein-coding sequences (specifically, coding exons) constitute less than 1.5% of the human genome. In addition, about 26% of the human genome is introns. Aside from genes (exons and introns) and known regulatory sequences (8–20%), the human genome contains regions of noncoding DNA. The exact amount of noncoding DNA that plays a role in cell physiology has been hotly debated. Recent analysis by the ENCODE project indicates that 80% of the entire human genome is either transcribed, binds to regulatory proteins, or is associated with some other biochemical activity.

A biological target is anything within a living organism to which some other entity, like an endogenous ligand or a drug is directed and/or binds. Examples of common classes of biological targets are proteins and nucleic acids. The definition is context-dependent and can refer to the biological target of a pharmacologically active drug compound, the receptor target of a hormone (like insulin), or some other target of an external stimulus. The implication is that a target is «hit» by a signal and its behavior or function is then changed. Biological targets are most commonly proteins such as enzymes, ion channels, and receptors.

Studies published by diMasi et al. in 2003, report an average pre-tax, capitalized cost of approximately $800 million to bring one of the drugs from the study to market. Also, this $800 million figure includes opportunity costs of $400 million. A study published in 2006 estimates that costs vary from around $500 million to $2 billion depending on the therapy or the developing firm. A study published in 2010 in the journal Health Economics, including an author from the US Federal Trade Commission, was critical of the methods used by diMasi et al. but came up with a higher estimate of ~$1.2 billion.

It has been suggested that clinical trial participants be considered to be performing ‘experimental’ or ’clinical labour’. Re-classifying clinical trials as labour is supported by the fact that information gained from clinical trials contributes to biomedical knowledge, and thus increases the profits of pharmaceutical companies. The labour performed by those participants in clinical trials includes the provision of tissue samples and information, the performance of other tasks, such as adhering to a special diet, or (in the case of Phase I trials particularly) exposing themselves to risk. The participants in exchange are offered potential access to medical treatment. For some, this may be a treatment with the potential to succeed where other treatments have failed. For other individuals, particularly those situated in countries such as China or India, they may be given access to healthcare which they otherwise would be unable to afford, for the duration of the trial. Thus, the exchange which exists may serve to classify clinical trials as a form of labour.

Classical pharmacology is one of the approaches used for clinical trials on Ayurvedic drugs. In this approach, a folk medicines (e.g., Ayurveda) which has already been in use for many years and has anecdotal evidence of efficacy for the treatment of a disease (and is also presumed to be safe) is then tested for efficacy in a clinical trial. This method has been described as ’reverse pharmacology’ by Dr. Ashok Vaidya.

Transposable genetic elements, DNA sequences that can replicate and insert copies of themselves at other locations within a host genome, are an abundant component in the human genome. The most abundant transposon lineage, Alu, has about 50,000 active copies, while another lineage, LINE-1, has about 100 active copies per genome (the number varies between people). Together with non-functional relics of old transposons, they account for over half of total human DNA. Sometimes called «jumping genes», transposons have played a major role in sculpting the human genome. Some of these sequences represent endogenous retroviruses, DNA copies of viral sequences that have become permanently integrated into the genome and are now passed on to succeeding generations.

As such, most entry-level workers in medicinal chemistry, especially in the U.S., do not have formal training in medicinal chemistry but receive the necessary medicinal chemistry and pharmacologic background after employment—at entry into their work in a pharmaceutical company, where the company provides its particular understanding or model of «medichem» training through active involvement in practical synthesis on therapeutic projects. (The same is somewhat true of computational medicinal chemistry specialties, but not to the same degree as in synthetic areas.) Hence, although several graduate programs offer Ph.D. and postdoctoral training in medicinal chemistry, the broader education of a top-tier synthetic or physical chemistry graduate program most frequently provides the entry level skills sought for industrial medicinal chemistry.

At a participating site, one or more research assistants (often nurses) do most of the work in conducting the clinical trial. The research assistant’s job can include some or all of the following: providing the local institutional review board (IRB) with the documentation necessary to obtain its permission to conduct the study, assisting with study start-up, identifying eligible patients, obtaining consent from them or their families, administering study treatment(s), collecting and statistically analyzing data, maintaining and updating data files during followup, and communicating with the IRB, as well as the sponsor and CRO.

Structure-based drug design (or direct drug design) relies on knowledge of the three dimensional structure of the biological target obtained through methods such as x-ray crystallography or NMR spectroscopy. If an experimental structure of a target is not available, it may be possible to create a homology model of the target based on the experimental structure of a related protein. Using the structure of the biological target, candidate drugs that are predicted to bind with high affinity and selectivity to the target may be designed using interactive graphics and the intuition of a medicinal chemist. Alternatively various automated computational procedures may be used to suggest new drug candidates.