The novel antimigraine drug 311C90 (Zomig; zolmitriptan) has a high selectivity for serotonin (5HT)1 receptors, mainly 5HT1B and 5HT1D subtypes, and in preclinical studies it has been shown to act on four different sites within the trigemino-vascular system (blockade of neurogenic inflammation by inhibition of peptide release, vasoconstriction, inhibition of neuronal depolarization at peripheral sites, and effects at central sites). Oral 311C90 has a favorable pharmacokinetic profile. It is rapidly absorbed, with 75% of maximal plasma concentration (Cmax) attained within 1 hour and good absolute oral bioavailability (approximately 40%). Clinical studies have shown 311C90 to be rapidly and consistently effective in relieving migraine headache, with initial doses of between 2.5 and 5 mg providing an optimal balance between efficacy and safety considerations. Moreover, the good tolerability of 311C90 is supported by clinical data showing that doses up to 10-fold the therapeutic dose (2.5 mg) did not raise any serious safety concerns, highlighting the favorable safety profile of this drug.