The free acid () and monohydrated calcium salt () forms of HMB have different pharmacokinetics. HMB-FA is more readily absorbed into the bloodstream and has a longer elimination half-life (3 hours) relative to HMB-Ca (2.5 hours). Tissue uptake and utilization of HMB-FA is  higher than for HMB-Ca. The fraction of an ingested dose that is excreted in urine does not differ between the two forms.