Ten young healthy men and women ingested 1 of 5
conditions on different days using a double-blind, randomized, crossover design. The following
were ingested after a 10-hour overnight fast: 250 mg caffeine (C), 50 mg geranamine (G 50 mg),
75 mg geranamine (G 75 mg), 250 mg caffeine + 50 mg geranamine (C + G 50 mg), and 250 mg
caffeine + 75 mg geranamine (C + G 75 mg). Heart rate, systolic blood pressure (SBP), diastolic
blood pressure (DBP), and rate pressure product (RPP) were measured pre-ingestion and at 30,
60, 90, and 120 minutes post-ingestion. Plasma norepinephrine (NE) and epinephrine (EPI)
were measured pre-ingestion and at 60 and 120 minutes post-ingestion. Results: Heart rate was
unaffected by treatment, but blood pressure and RPP were higher with geranamine, generally in
a dose-dependent manner. The peak percent change from pre-ingestion in SBP (∼20%), DBP
(∼17%), and RPP (∼9%) was noted with C + G 75 mg at 60 minutes post-ingestion. Plasma NE and
EPI were relatively unaffected by treatment. Conclusion: We report for the fi rst time that acute
ingestion of 1,3-dimethylamylamine alone and in combination with caffeine results in an increase
in SBP, DBP, and RPP without an increase in HR. The largest increase is observed at 60 minutes
post-ingestion of C + G 75 mg. These changes cannot be explained by circulating NE and EPI.