Comparative Bioavailability and Benefits on Mental Functions of Novel Extended-Release Caffeine Capsules against Immediate-Release Caffeine Capsules: An Open-Label, Randomized, Cross-over, Single-Dose Two-Way Crossover Study.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 36602880 · doi:10.1080/19390211.2022.2160529
What was done
An open-label, randomized, single-dose, two-sequence, two-period crossover trial evaluated the relative bioavailability and subjective mental effects of 200 mg sustained-release caffeine (SR-Caffeine, CaffXtend®) versus 200 mg immediate-release caffeine (IR-Caffeine) in 15 healthy fasting adults. Blood samples were drawn across 48 hours post-dose to measure pharmacokinetics, and subjective mental states were evaluated using the caffeine research visual analogue scale (Caff-VAS).
What was found
All 15 participants completed the study. SR-Caffeine significantly delayed mean t_max compared to IR-Caffeine (4.08 ± 2.13 h vs. 0.83 ± 0.39 h, p < 0.0001) and prolonged mean elimination half-life t_1/2 (7.07 ± 3.48 h vs. 5.78 ± 2.11 h, p = 0.04189). Total exposure was bioequivalent, with 90% confidence intervals within standard boundaries for ln-transformed AUC_0-t (89.89–120.50%) and AUC_0-∞ (94.49–123.82%). SR-Caffeine produced significantly better Caff-VAS scores for alertness, tiredness, jitteriness, and overall mood spanning 8 to 12 hours post-dose. No adverse events were reported.
Why it matters
This formulation demonstrates sustained caffeine delivery with bioequivalent total absorption, prolonging subjective alertness benefits through 8–12 hours without increasing acute jitteriness.
Limits
The sample size was very small (n = 15). The open-label design introduces significant risk of expectation bias for subjective mood and alertness ratings on visual analogue scales, and objective cognitive testing metrics were not reported in the abstract.
Cited by
- supports Peak alertness effects of caffeine occur approximately 30 minutes after ingestion.
- supports Caffeine concentrations in the body peak approximately 30 minutes after consumption.