No Reinforcement
Cocaine: Blocked From the Brain
TA-CD is a vaccine designed to elicit production of antibodies to bind cocaine molecules in the blood stream and prevent them from
entering the brain. This eliminates the drug's psychoactive effect. By blunting the pleasurable experience associated with
cocaine, TA-CD can reinforce a treatment plan including substance-abuse counseling and related therapy. "Vaccines are a very
rational approach for a substance with the profound reinforcing effects of cocaine," says Barbara Mason, professor, Committee
on the Neurobiology of Addictive Disorders at Scripps Research Institute in La Jolla, CA. "But you have to have patients who
are willing to take the drug. I'm thinking niche drug instead of wide-scale treatment."
Head to Head
Migraine: As Effective as Rizatriptan
Migraine afflicts almost one in five women and more than one in 20 men. Roughly two of three patients who suffer these debilitating
headaches experience relief from Maxalt (rizatriptan), the current standard, which Merck launched in 2003.
In a head-to-head Phase IIb comparison MK 0974 was as effective as rizatriptan in relieving pain two hours after administration, according to Alan Rapoport, MD, clinical
professor of neurology at UCLA Medical School and founder/director-emeritus of the New England Center for Headache in Stamford,
CT. Among 420 patients, 68.1 percent of those taking 300-milligram doses of MK 0974 reported no pain after two hours, compared
with 69.5 percent of patients taking rizatriptan. At the 24-hour mark, 39.6 percent of MK 0974 patients were pain free compared
with 18.4 percent of rizatriptan patients. Phase III trial results are expected within a year, according to Rapoport.
Both MK 0974 and BIBN 4096 are calcitonin gene-related peptide (CGRP) receptor antagonists. (Rizatriptan is a selective agonist at serotonin 1D and
serotonin 1B receptors.) BIBN 4096 proved efficacious and safe in a 2004 Phase II clinical trial and was celebrated as a breakthrough
in the New England Journal of Medicine. But it has not moved forward in the clinic for three years, and it is an injectable—not desirable in a headache drug. MK
0974 is a tablet taken by mouth.
Rapoport and other clinicians hope that many patients who do not respond to triptans will get relief from CGRP antagonists.
"MK 0974 is clearly effective against migraines," Rapoport said. "But there is still a lot we don't know about how exactly
it works."
Making Cocktails
HIV: Mix-and-Match Therapies
No new HIV drug is conceived as a monotherapy. As new molecules and mechanisms, emerge, the first question is how they fit
into existing therapies."HIV patients have very different needs when it comes to viral suppression, side effects, and so on,"
said Sylvia Eash, an analyst at Decision Resources. "New drugs are tested in treatment-experienced and treatment-naïve patients—and
always in combination with other drugs."
Bevirimat is the first drug to inhibit the growth of an HIV particle by preventing a precursor protein from maturing into capsid, one
of the key proteins of the mature virus. Panacos has had some difficulties in creating a capsule version of the drug, which
has been tested mostly in liquid form.
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