Pharmacokinetics of sumatriptan in non-respondent and in adverse drug reaction reporting migraine patients

Sumatriptan is a selectiveagonist of 5HT1 (1B/1D) receptors,which has proved to be effectiveand safe for the acute treatment ofmigraine attacks. Nevertheless, itsuse by migraine sufferers is stilllimited and some patients consideradverse reactions related to sumatriptan,especially chest symptoms,unacceptable even if not serious.Moreover, in clinical trials, almostone third and one sixth of patients,respectively, fail to experienceheadache relief either after oral orafter subcutaneous sumatriptanadministration. Our aim was to verifywhether differencies in sumatriptanpharmacokinetics couldexplain non-response and/oradverse drug reactions. Sumatriptanlevels were determined by HPLCwith electrochemical detection.Pharmacokinetic parameters werecalculated using a computer program(PK Solutions 2.0; non compartmentalPharmacokinetics DataAnalysis). After oral administration,sumatriptan is rapidly absorbed andsometimes displays multiple peaksof plasma concentration. This “multiplepeaking” gives rise to considerableinter-subject variability inthe time of reaching maximumplasma concentration.Pharmacokinetic parameters ofsumatriptan, both after oral andsubcutaneous administration, weresimilar in the three patient groups.Blood pressure and heart rate didnot show any significant differencesbetween groups. Pharmacokineticparameters and bioavailability ofsumatriptan did not seem to be correlatedeither to the lack of efficacyor the appearance of side effects.These results could depend on thelimited number of patients studied.