CNS Effects of Sumatriptan and Rizatriptan

Abstract

CNS effects of sumatriptan and rizatriptanDear sir In their recent article, van der Post et al. (1) reported results from a study in which rizatriptan 10 mg and sumatriptan 100 mg were found to have minimal CNS effects, compared with temazepam 20 mg, on a battery of psychometric tests administered to 17 healthy women. Rizatriptan produced slightly greater impairment than sumatriptan, and the authors suggested that rizatriptan effects may have been underestimated because of encapsulation. The clinical relevance of these small differences between rizatriptan and sumatriptan in healthy women is unclear. To investigate this issue, we retrospectively analysed adverse event data from a large randomized, double-blind, placebo-controlled study which directly compared rizatriptan 10 mg with sumatriptan 100 mg for the treatment of a migraine attack (2). Supplies of rizatriptan and sumatriptan were not encapsulated. We looked at the percentages of migraine patients with any CNS adverse event, or with specific CNS adverse events of dizziness and drowsiness (the 2 most common CNS adverse events following triptan use). The results are shown in Table 1. There was no evidence that rizatriptan resulted in more CNS adverse events than sumatriptan. In fact, a slightly higher percentage of patients taking sumatriptan reported any CNS adverse event compared with patients taking rizatriptan. Both rizatriptan and sumatriptan were associated with an increase in CNS adverse events compared with placebo, but most events were of mild or moderate severity and were short-lasting. A study which directly compared rizatriptan 10 mg with the lower, 50-mg, dose of sumatriptan also found similar percentages of patients with CNS adverse events in the active treatment groups (3). These results suggest that, clinically, rizatriptan and sumatriptan have similar CNS effects.

Does sumatriptan cross the blood–brain barrier in animals and man?

“…The CNS adverse events of triptans can, however, be partly ascribed to migraine symptoms being unmasked by effective treatment since responders to eletriptan had more CNS AEs than non-responders to eletriptan [45]. However, in one large RCT [46] any CNS adverse events were more frequent after sumatriptan 100 mg (29.6%) ( n  = 386) than after rizatriptan 10 mg (22.5%) ( n  = 385) [47] despite the fact that the two drugs were equipotent for headache relief after 2 h [46]. In addition, rare cases of central nervous system AEs such as akathesia, acute dystonia and pathological laughter have been described after subcutaneous and oral sumatriptan used in the treatment of migraine and cluster headache [48–50].…”