New Gains for Pain - Pharmaceutical Executive


New Gains for Pain
The palliative-care market is set to explode. Here's an overview of what to expect.

Pharmaceutical Executive

Although Lyrica's approval in the European Union and approvable status in the United States is good news for Pfizer, another drug from rival Eli Lilly recently received a lot of press when it became the first medicine to be approved by FDA specifically for neuropathic pain associated with diabetic peripheral neuropathy. Cymbalta (duloxetine), a serotonin and norepinephrine reuptake inhibitor, had been given a six-month priority review and had also been approved one month earlier for major depression in adults. In the past, antidepressants were often prescribed off-label as first- and second-line pain treatments.

Despite Cymbalta's first-to-market edge in the United States, Navigant's consultants predict that after it gets FDA approval, Lyrica will eventually lead expansion of the worldwide neuropathic pain market, a segment expected to reach $3.5 billion by 2009. Last year, Neurontin, Lyrica's predecessor, alone accounted for $2.7 billion in sales, and Lyrica will likewise achieve blockbuster status.

New Approaches Although opioids and NSAIDs—which have been around for decades—are the standard treatments for most pain indications, there are several emerging therapeutics with new mechanisms of action. This is particularly true in the neuropathic pain segment, an area in which opioids and NSAIDs have shown limited efficacy.

Elan's Prialt (ziconotide) is a synthetic form of a Conus snail venom peptide (conotoxin M-VII-A) and acts as an N-type neuron-specific calcium channel blocker. Under clinical development for chronic pain relief—including cancer, neuropathic, and postoperative pain—it is expected to provide an important new treatment option for neuropathic pain sufferers.

GW Pharmaceuticals' Sativex, a cannabinoid receptor agonist (similar to the compound in marijuana), is being developed for the UK (cancer pain, neuropathic pain, postoperative pain) and Canadian (pain, neuropathic pain) markets. Consisting of a whole plant medicinal cannabis extract, Sativex is administered as a mouth spray.

GlaxoSmithKline's Lamictal is an anticonvulsant with a novel chemical structure measured against other available drugs in its class and is thought to act as a glutamate antagonist. It is currently approved for the treatment of bipolar disorders, partial seizures, and Lennox-Gastaut syndrome in various countries and is in Phase III for neuropathic pain in the United States.

Other novel drugs expected to enter the pain market during the next five years include Novartis' Aredia (pamidronate), DOV Pharmaceutical's bicifadine, and Allergan's Botox (botulinum toxin A). Aredia, a bisphosphonate, is currently used off-label for cancer pain when cancer has metastasized to bone. Aredia is a potent inhibitor of bone resorption, thereby maintaining bone mineral density. It is thought to prevent the attachment of osteoclast precursor cells to bone. It is currently marketed for osteoporosis and other bone disorders, and is in Phase III in the US for the management of malignant bone pain. It is also under development for similar indications in Japan (Phase II) and Switzerland (unidentified clinical phase).

Bicifadine is a novel analgesic with an unidentified mechanism of action. It is understood, however, to enhance and prolong the activity of norepinephrine and serotonin and is a functional antagonist at a subset of excitatory glutamate receptors. It is under development for a broad pain indication and has been under clinical investigation for several different pain conditions, including moderate to severe postsurgical dental pain and chronic lower-back pain.


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