The thigh may not be suitable as an injection site for patients self-injecting sumatriptan

The objective of our study was to evaluate the differences between injection sites in the midthigh and the upper lateral quadrant of the gluteal area regarding the effect, depth of subcutaneous tissue, side effects, and patient preference in patients with cluster headache who self-inject 6 mg (0.5 ml) of sumatriptan. Our open, prospective clinical study was performed at the outpatient department of a Swedish university clinic. There were 19 male and one female subjects, 34 to 68 years old, suffering from cluster headache. We measured the subcutaneous tissue depth by ultrasound. Subjects performed four self-injections of sumatriptan, two in the thigh and two in the gluteal area. We evaluated the subcutaneous tissue depth from the skin surface to the muscle fascia, the effect on headache, side effects, and patient preference regarding the injection site. Subcutaneous tissue depth laterally in the thigh was 2 to 12 mm (median, 4 mm) and in the gluteal area was 34 to 68 mm (median, 45 mm). The needle of the self-injector protrudes 5 to 6 mm. Forty thigh and 39 gluteal injections were recorded. The effect on headache was equal. Following injection in thigh the patients experienced more bleeding (p < 0.001, chi 2); local pain (p < 0.05, chi 2); and a feeling of oppression in the head, neck, and chest area (p < 0.05, chi 2); compared with injections in the gluteal area. Fifteen patients preferred the gluteal area as the injection site after the study, two patients had no preference, and three preferred the thigh. When using the self-injector in the lateral aspect of the thigh, intramuscular injection is liable to occur frequently in male patients. This may explain the differences in local and general side effects observed in this study. The upper lateral quadrant of the gluteal area is a more suitable injection site for male, and some female, patients when using the sumatriptan self-injector.