Abstract Body (Do not enter title and authors here): Background: Growing evidence supports a therapeutic role for ketones in HFrEF. However, no pharmacokinetic (PK) studies are available to guide further investigation, and uncertainty exists regarding use with the ketogenic SGLT2i and dose-dependent effects.
Methods: We conducted a phase I trial of two doses of ketone ester (KE, 250 mg/kg and 500 mg/kg) in 20 HFrEF participants, stratified by SGLT2i use. Non-compartmental analysis assessed PK parameters of ketones. Paired t-tests and generalized linear mixed models assessed changes in mass-spectrometry based targeted metabolites, blood gas, and vital sign assessments up to 4 hours after dosing.
Results: The mean age was 66.0±14.8 years, 45% were women, 30% were non-White, and average EF was 33±13%. The median (25^th–75^th percentile) T_max, C_max, and T_1/2 for total ketones with 250 and 500 mg/kg doses were 1.01 (0.64-1.24) and 1.58 (1.06-1.99) hours, 2317 (2165-2491) and 3354 (3291-3538) µM, and 0.85 (0.66-1.24) and 2.04 (1.36-3.47) hours, respectively (Figure 1A). One hour after KE consumption, insulin levels robustly increased, while non-esterified fatty acids, branched-chain amino acids, and acylcarnitines decreased except for C2/C4-OH acylcarnitines, which increased (FDR-adjusted p-value<0.05). Increases in ketones and C2/C4-OH acylcarnitines were dose-dependent, while background SGLT2i was associated with blunting of the decrease across acylcarnitines. One hour post KE, heart rate initially rose by 4 (95%CI 2-6) beats/min, while systolic blood pressure (-7, 95%CI -12, -2 mmHg), pH (-0.07, 95%CI -0.08, 0.05), and bicarbonate (-3, 95%CI -4, -2 mEq/L) decreased, with dose-dependent acid-based effects (Figures 1B-C). These values returned close to baseline by 4 hours. Adverse events were infrequent and mild.
Conclusions: Acute KE ingestion is associated with rapid changes in several key metabolic pathways, with differential effects imparted by background SGLT2i (fatty acid metabolism) and dose (ketone metabolism). Hemodynamic effects were transient and irrespective of dose/SGLT2i, while acidotic effects were heightened with increasing dose. These data support the safety of combined KE and SGLT2i in HFrEF and provide grounding data for further trials.