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| |  Central Brain Sites Hold the Key to Effective Migraine Remedies BUENOS AIRES, ARGENTINA -- September 17, 1997 -- Data presented at the World Congress of Neurology points to growing evidence of the importance of central sites in the brain in the mode of action of new 5-HT IB/ID receptor agonists, the new acute anti-migraine therapies such as zolmitriptan . Research is going on in a number of areas relating to the mechanisms of migraine and of its treatment, highlighting the crucial role which central sites in the brain may play in effective acute migraine therapies. 5-HT (5-hydroxytryptamine) is found throughout the body and mediates a wide variety of physiological effects, including the perception of pain, depending on the receptors to which it binds. The newer 5-HT IB/ID agonists, such as zolmitriptan and sumatriptan, which have the ability to act both centrally as well as peripherally within the brain, may confer clinical advantages over products which do not act centrally. Walls of the blood vessels supplying the brain are selectively permeable, forming a barrier to infecting micro-organisms and chemical substances. Accordingly, newer 5-HT IB/ID agonists with a higher lipophilicity are able to cross the blood brain barrier and access brainstem components involved in processing cranial pain. This highlights the role which central neuro-inhibitory actions play in migraine. In addition, zolmitriptan exhibits a favorable oral bioavailability together with robust pharmacokinetics and therefore a greater proportion of this particular drug reaches the systemic circulation and is available for distribution to the central site of action in the brain. All these properties distinguish zolmitriptan from sumatriptan which exhibits a low bioavailability and doesn't cross the intact blood brain barrier. However, speaking at the WCN, Professor Jean Schoenen, Research Director and Clinical Professor, University Department of Neurology, Liege, Belgium, said it is not sufficient for a compound to cross the intact blood brain barrier and modify the central nervous system (CNS) functions relevant to the migraine pathway. It must also be proved that these attributes improve its efficacy as an anti-migraine therapy. Moreover, these attributes cannot be achieved at the expense of an increase in CNS-related adverse events. In a head-to-head clinical trial comparing zolmitriptan with sumatriptan, this was not the case, with the incidence of CNS-related adverse effects reported being similar in both treatment groups. Professor Schoenen explained the most favorable profile for a migraine treatment appears to be a moderate degree of lipophilicity and, therefore, a moderate penetration into the central nervous system. This indicates that a 5-HT(1) agonist such as zolmitriptan will offer the optimal benefit for migraine sufferers.
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