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Tag "cgrp"

A good predictor of response to Botox injections in chronic migraine patients has been found by Spanish researchers.

While Botox is a very effective treatment for chronic migraines and possibly other types of headaches and pain, it does not help everyone. Approximately 30% of patients with chronic migraine headaches do not respond to Botox. We usually try at least two sets of injections three months apart before considering the patient to be a non-responder. Considering that Botox is an expensive treatment, it would be very useful to know beforehand which patients will respond and which will not. Besides the cost, it would also save patients time, during which they could be trying other treatments.

Some studies show that having a constricting headache or pain in the eye is usually a positive predictor of response to Botox. On the other hand, exploding headache (that is when the pain is felt pushing from the inside out), is less likely to respond to Botox injections. However, these are very subjective descriptions and predictions based on them are not that reliable.

A new study by Spanish researchers just published in the journal Headache reported that the levels of CGRP (calcitonin gene-related peptide) and VIP (vasoactive intestinal peptide) in patients’ blood are good predictors of response to Botox in chronic migraine sufferers. These two chemicals, which circulate in the blood and perform various important functions in the brain have long been the subject of scientific research. Actually, we think that Botox works by blocking the release of CGRP from the peripheral nerve endings. Dr. Julio Pascual and his colleagues measured the levels of these two chemicals in chronic migraine patients before they were treated with Botox. Botox was administered according to the standard protocol every 12 weeks for at least two treatment cycles. A patient was considered a moderate responder when both: 1) moderate-severe headache episodes were reduced by between 33 and 66%; and 2) subjective benefit on a visual scale from 0 to 100 was recorded by the patient of between 33-66%. Patients were considered to be excellent responders when both items improved by more than 66%. Those without improvement of at least one-third in the two items were considered as nonresponders.

The study involved 81 patients with chronic migraine and 33 healthy controls. CGRP and VIP levels were significantly increased in the chronic migraine population vs controls. CGRP and, to a lesser degree, VIP levels were significantly increased in responders vs nonresponders. The probability of being a responder to Botox was 28 times higher in patients with a CGRP level above the threshold.

The measurement of CGRP and VIP is done only by research institutions and is not yet offered by commercial laboratories. However, considering how much money can be saved by not giving Botox to those who are unlikely to respond, these tests should become widely available once these findings are confirmed by other researchers.

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A new treatment for migraines is very effective and well tolerated, according to a paper published in Neurology.  Two years ago I mentioned on this blog that this new migraine drug did well in Phase II trial and now the results of Phase III also appear to be very positive.   The study was double-blind and placebo-controlled and involved more than 1,200 patients.  The drug’s chemical name is telcagepant and it belongs to a new family of migraine drugs, CGRP antagonists.   They work on a different receptor than the triptans (sumatriptan or Imitrex and similar drugs) and appear to be as effective.  Possible advantages of this drug are that it may work when triptans are ineffective and it does not appear to constrict coronary blood vessels, which can happen, albeit rarely, with triptans.

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Scientists in Trieste, Italy suggested a new approach to the treatment of migraine headaches.  They hypothesized that combining two different approaches would yield better outcomes than either one alone.  A neurotransmitter CGRP antagonists appear to be effective in the treatment of an acute migraine.  Merck has a product in late stages of development that works through this mechanism and hopefully will be the first of a new class of migraine drugs.  Based on laboratory research the Italian group suggests that combining a CGRP antagonist with a blocker of nerve growth factor may result in a more effective treatment.  This fits with a new trend in treatment of many conditions – combining drugs that work in different ways, rather than trying to always use a single medication.

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