It is an obvious phenomenon that a huge amount of money has been invested in drug research and development (R&D) in previous few decades but highly innovative novel medicines in large amounts has not been approved by the US Food and Drug Administration (FDA). Moreover, attrition rates are high. According to the experts, “technical success” and “target selection” are among the most important aspects to reduce attrition and increase R&D productivity.Experts are working on the secret behind the challenging R&D productivity, even after so many powerful tools have been devised to identify potential drug candidates. Why is this so that molecular mechanisms of the drugs are becoming clearer with each passage of time but novel approaches to treat them are still in fewer amounts?
There are two most important screening techniques in R&D, i.e. target-based screening and phenotypic screening, for the use of drugs against a particular disease. Target-based screening refers to the use of drug on the basis of the knowledge of molecular targets while phenotype refers to the visible characteristics of the organism. In case of target-based screening, we are often unaware of the actual mechanism and use drug on the basis of hypothesis.
Following are points related to certain drugs which can be researched on while considering R&D;
- Daptomycin is an anti-infective agent developed by Cubist by the name by Cubicin. Its molecular mechanism of action is not known.
- Docosanol is an anti-infective agent by Avanir Pharmaceuticals and available by the name of Abreva. Not only its target type but also its molecular mechanism of action is not known.
- Levetiracetam is used for psychiatric and neurologic conditions. It is available under the trade name Keppra and manufactured by UCB Pharmaceuticals. However, its target type and molecular mechanism of action, both are still unknown.
- Lubiprostone is used for Gastrointestinal disorders. It is available under the trade name of Amitiza and manufactured by Sucampo Pharmaceuticals. However, both the target type and the molecular mechanism of action are still not known.
- Nateglinide is used for the treatment of type-2 diabetes. It is available under the trade name of Fastic and Starlix. Its target type is still unknown.
- Pemirolast is used for allergic conditions. It is marketed under the trade names of Alamast and Alegysal. Both the target type and the molecular mechanism of action of this drug are unknown.
- Ranolazine is used for Cardiovascular conditions. It is marketed under the trade name of Ranexa by Gilead. Its target type and molecular mechanism of action both are still unknown.
- Rufinamide is used for certain CNS conditions. It has trade name of Inovelon by Novartis. Its target type and molecular mechanism of action are not known.
- Sinecatechins is an anti-infective agent. It has trade name of Veregen by Medigene. Its molecular mechanism of action and the target type both are not clear.
- Zonisamide is used for certain CNS conditions. Its trade name is Excegran by Dainippon Pharmaceuticals. Its molecular mechanism of action and the target type both are not clear.
David C. Swinney and Jason Anthony, (2011). How were new medicines discovered? Nature Reviews-Drug Discovery, doi:10.1038/nrd3480