Efficacy and adverse events of subcutaneous, oral, and intranasal sumatriptan used for migraine treatment: a systematic review based on number needed to treat.

OBJECTIVES: To evaluate the efficacy, speed of onset, and adverse events of 6 mg subcutaneous, 100 mg oral, and 20 mg intranasal sumatriptan in the treatment of migraine attacks.
DESIGN: Systematic review of placebo-controlled randomized clinical trials. DATA SOURCES: Thirty trials up to April 1997 retrieved from a systematic literature search (Medline, review papers, handsearching of journals, congress proceedings, manufacturer's database); no restriction on language. OUTCOME PARAMETERS: Numbers needed to treat (NNT) were calculated for relief of headache and for adverse events (when data were available). Therapeutic gain was used to evaluate speed of onset of action.
RESULTS: Subcutaneous sumatriptan was more efficacious, combined number needed to treat 2.0 at 1 h, than oral (3.0 at 2 h) and intranasal sumatriptan (3.1 at 2 h). For adverse events, the NNT was 3.0 for subcutaneous and 8.3 for oral sumatriptan. Only limited data on adverse events for intranasal sumatriptan were available. Therapeutic gain analysis during the first 2 h showed that subcutaneous sumatriptan was the fastest-acting form of administration.
CONCLUSIONS: Subcutaneous sumatriptan in a dose of 6 mg is significantly more efficacious than 100 mg of oral sumatriptan, but causes more adverse events than oral sumatriptan. Subcutaneous sumatriptan is the form with the quickest onset of action. Intranasal sumatriptan has the same efficacy as oral sumatriptan and a quicker onset of action than the oral form, but with a limited therapeutic effect for the first 30 min after administration.