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

Present study aimed compared pharmacokinetic profile of sustained-release CaffXtend® capsules (SR-Caffeine) with immediate-release caffeine capsules (IR-Caffeine), and the effect of SR-caffeine on memory, motivation, concentration, and attention. This open-label, randomized, single-dose, two-treatment, two-sequence, two-period, two-way crossover oral bioavailability study block randomized (1:1) healthy subjects (N = 15) to receive SR-Caffeine (200 mg) and IR-Caffeine (200 mg). Blood samples were collected at 0.25, 0.50, 0.75, 1, 1.5, 2, 3, 4, 5, 6, 8, 10, 12, 24, 36 and 48 h in each period. Primary study outcome included comparing relative bioavailability of SR-Caffeine 200 mg and IR-Caffeine 200 mg under fasting conditions, and changes in caffeine research visual analogue scale (Caff-VAS) scores (‘relaxed’, ‘alert’, ‘jittery’, ‘tired’, ‘tense’, ‘headache’, ‘overall mood’ and ‘mentally fatigued’) were also evaluated. Fifteen subjects completed the study. Mean tmax was 4.08 ± 2.13h for SR-Caffeine compared to 0.83 ± 0.39h for IR-Caffeine, (p < 0.0001). Similarly, mean t½ was 7.07 ± 3.48h for SR-Caffeine compared to 5.78 ± 2.11h for IR-Caffeine (p = 0.04189). However, total exposure was similar for SR-Caffeine and IR-Caffeine (90% CI: 89.89–120.50% to 94.49–123.82% for geometric least square mean of ln-transformed AUC0-t and AUC0-∞). In the Caff-VAS evaluation, the SR-Caffeine group showed significantly better scores for ‘jitteriness’, ‘tiredness’, ‘alertness’ and ‘overall mood’ for 8–12 h than the IR-Caffeine group. No adverse events were reported. Results demonstrated sustained release of caffeine over 24 h from SR-Caffeine as compared to IR-Caffeine, which showed significant improvements in the scores for ‘relaxed’, ‘alertness’ and ‘overall mood’ and significantly lower scores for the parameters-‘jittery’ and ‘tired’ for extended period.Clinical trial registration: CTRI/2021/06/034185