Pharmacokinetic Profile of the Calcium-salt and Free Acid Forms of β-hydroxy-β-methylbutyrate in Humans

HMB supplementation has been shown to have potential to optimize resistance training responses, which may have important implications for sport, exercise, and health. However, HMB literature shows uncertainties as to which is the superior pharmaceutical form of supplemental HMB (i.e., the calcium salt or the free acid form) in terms of pharmacokinetic profile and bioavailability when consumed by humans. This research project investigated the bioavailability and pharmacokinetics of two different forms of supplemental HMB, namely HMB calcium-salt (HMB-Ca) and HMB Free Acid (HMB-FA). Further, HMB-Ca was provided both diluted in water and encapsulated in gelatine capsules. This pharmacokinetics study adopted a crossover design, open-label design in which male and female participants visited the laboratory on 3 different occasions to receive one the 3 treatments: 1g of HMB; the equivalent of 1g of HMB-Ca in water; the equivalent of 1g of HMB-Ca in gelatine capsules. Venous blood samples were collected before and multiple time points after treatment ingestion, for a period of 12 hours in total. A pre-ingestion midstream urine sample was collected as well as a 24-h post-ingestion total urine sample. All plasma and urine samples were analysed for their HMB concentrations via LC/MS. Time to peak, maximum concentration, area under the curve, half-life time and slope of the incremental phase were calculated to examine the pharmacokinetic profile of HMB and compare the 3 different pharmaceutical forms.