Pain affects all of us sometimes and many of us all the time. Yet, the pharmacologic therapies available to alleviate pain have changed little in the last 50 years. Those who suffer from acute pain originating in the peripheral nervous system have the best chances of finding relief, while others suffering chronic neuropathic pain must often settle for partial or even minimal relief.
D&MD’s pain therapeutics report explores the progress in drug discovery and development for postsurgical, neuropathic, and psychogenic pain as well as pain related to cancer, AIDS, arthritis, head, and back.
Although the nonsteroidal anti-inflammatory drug (NSAID) field took a mighty blow from problems with COX-2 inhibitors and the failure of a number of compounds once thought promising to make it through the pipeline, some contenders remain standing, and several new drug targets have emerged in recent years.
D&MD’s pain therapeutics report estimates total pain therapeutic sector sales for 2005 of approximately $31 billion, with prescriptions accounting for about two-thirds of that total. It forecasts sales growth averaging 9% for the period ranging from 2006 through 2010.
Survey results within this report indicate that 29% of pain drug discovery programs address new targets. The incidence of programs addressing new targets is highest in big pharma, and development activity in the COX-2 area is strongly depressed. The survey sample size includes 32 scientists and managers in commercial pain drug discovery and development and is evenly divided among big pharma, small pharma, and biopharma. Other observations from the survey indicate that big pharma has been quite successful in generating new pain drug targets using genome-era technologies and respondents are predominantly optimistic that better drugs to treat neuropathic pain will enter the market in the next five years.
Although the basic pain research community has succeeded remarkably in identifying new molecular components of pain pathways, they have not yet been markedly successful in providing an overall systems biological context that allows rational targeting of pain drug candidates. The need for new pain drugs remains great, both from the perspective of inadequacy of existing therapies and current market demographics. However, several targets now show signs of yielding improved therapies, and it appears likely that in the near future patients and physicians will be able to select from a broadened menu of analgesics tailored to particular types of pain.
In vitro approaches to pain drug screening and evaluation are becoming increasingly popular with the introduction in recent years of equipment for moderate- and high-throughput screening of ligand-ion channel target interactions. Many of the targets currently in use for discovery and development of pain drugs are either ion channels or G protein-coupled receptors, although a number of others exist outside these two categories. Much of the pain R&D activity in process today deals with various forms of chronic pain, particularly the neuropathic variety.
The recent shrinkage of the COX-2 market removes a major growth factor from the pain drugs sector and while its reputation has been irreparably damaged, surviving members of the class will be used within two or three years for relatively short periods of time mainly by patients who clearly cannot tolerate other NSAIDs. The majority of patients who took COX-2 inhibitors without requiring them will get nearly equivalent analgesia from lower-priced generic or commoditized alternatives.
Deal activity in pain therapeutics during the past few years has been relatively light, with Merck & Co. and Pfizer standing out among big pharmas in the areas of product and company acquisitions.