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Endo Pharmaceuticals Pain Drug Falters Again in Phase III Studies

Oct 28, 2002
Reuters Health

Endo Pharmaceuticals Holdings Inc.'s said on Monday that it would discontinue development of its pain drug MorphiDex due to poor study results. The firm announced that the investigational product failed to meet the primary and secondary endpoints in a second phase III study.

The company was advancing MorphiDex, a combination of morphine and the N-methyl-D-aspartate (NMDA)-receptor antagonist, dextromethorphan, to treat chronic pain. The results disclosed on Monday involved a phase III trial that compared MorphiDex with immediate-release morphine sulfate in 327 patients.

"We are disappointed to report that investigators did not observe a statistically significant difference between the two groups regarding the primary endpoint of superior analgesia," Endo Chairman and CEO Carol Ammon told investors in a conference call. Ammon also noted the drug did not meet its secondary endpoint of a reduction in opioid analgesic tolerance.

While the outcome of a third phase III trial of MorphiDex should be available shortly, Ammon said the company had sufficient data to "suggest that we will not have enough evidence to support the filing of an amendment to the MorphiDex NDA."

In the double-blind trial results reported Monday, chronic pain patients were randomized into two arms at approximately 30 medical centers in the US. In the first, unblinded part of the study, all patients had their pain stabilized on MorphiDex.

If patients achieved satisfactory pain control on a stable dose of MorphiDex during the first period, they were then divided in a double-blind manner to receive a similar dose of morphine sulfate, either alone or in combination with MorphiDex. In the double-blind phase, investigators instructed patients to maintain the same daily dose of study medication for three months and not to take any additional pain medication. If patients were unable to maintain the same dose for any reason, they were discontinued from the study.

The company had advised in January 2002 that it would not seek US approval for MorphiDex until late 2002 because of slow enrollment in the drug's clinical trials. Endo previously had stated its intent to seek approval in mid-2002.

© 2002 Reuters Ltd