Abstract
Background: Dietary supplements purported to improve focus and “energy” often contain stimulants, which elevate both heart rate (HR) and blood pressure (BP). We evaluated the safety profile of the purine alkaloid methylliberine (Dynamine®) with regards to resting HR, BP, respiratory rate (RR), and body temperature (BT).
Methods: 6 men (aged: 24±4) and 6 women (aged: 22±3) ingested methylliberine (Dynamine®; Compound Solutions, Inc.) at 25mg (M25) and 100mg (M100), caffeine at 150mg (C150), M100+C150, M100 + theacrine (Teacrine®, Compound Solutions, Inc.) at 50mg (M100+T50), and M100+T50+C150. All conditions were assigned using a Latin square design, with approximately one week separating the six different assignments. HR, BP, RR, and BT were collected at baseline and 0.25, 0.5, 1, 1.5, 2, 4, 6, 8, 24, and 48 hours post-dose. Subjective mood was also recorded. Meal replacement bars and shakes were provided after hours 3 and 6.
Results: For SBP and DBP, condition effects were noted (p<0.05), with all three caffeine conditions higher than those without caffeine. Condition effects were noted for attentive (p=0.02) and energetic (p=0.02), with M100+C150 greater than M100+T50; and moody (p<0.01), with M100 and M100+T50 greater than M100+C150. Main effects of time were noted for HR (p<0.001), BT (p<0.01), SBP (p<0.01), DBP (p<0.01), and focused (p=0.02), but no statistically significant interactions were noted.
Conclusion: Methylliberine, alone or in combination with caffeine and/or theacrine, does not result in any significant increase in HR, BP, RR, or BT in healthy adults and has little impact on subjective mood. These findings should be considered with the understanding that subjects began testing in the early morning hours while in a fasted and rested state and were provided with two meals (hours 3 and 6) during the evaluation period, which may have impacted subjective mood.