SNAC co-formulation produces significant enhancement of oral vitamin B12 bioavailability in rats

Gastrointestinal absorption of Vitamin B12 (B12) is limited by the active intrinsic factor (IF) receptor mediated transport process. The prevalence of vitamin B12 deficiency is high, particularly in older adults, and many are currently treated with parenteral therapy due to problems with absorption through oral routes. This study evaluated the oral bioavailability of B12 co-formulated with SNAC (Sodium N-[8-(2-hydroxybenzoyl)amino]caprylate) in comparison to intravenous and oral B12 alone. Sprague-Dawley rats were dosed with B12 intravenously (0.5 mg/kg) alone, or orally (10 and 50 mg/kg) alone or in combination with SNAC (200 mg/kg). Blood samples were collected at pre-dose and selected post-dosing time points. Serum samples were analyzed for B12 by radioimmunoassay. Non-compartmental PK metrics obtained following B12/SNAC were compared to those following B12 alone. The extent of B12 absorption was substantially enhanced when B12 was administered in combination with SNAC. Absolute bioavailability was 7 to 10 % following B12/SNAC and only approximately 0.5 % following B12 oral administration. These data demonstrated that B12 co-formulated with SNAC enhances B12 GI absorption through a route other than the saturable receptor mediated uptake mechanism. Therefore, the oral formulation of B12 with SNAC is potentially therapeutic for B12 deficient individuals including those lacking IF and /or receptor.