Nasal absorption of hydroxocobalamin in healthy elderly adults

Aims To investigate the nasal absorption of hydroxocobalamin in 10 healthy elderly adults. Methods In a cross-over study, blood samples were collected before administration of the drug and after 10, 20, 30, 40, 60, 120, 180 and 240 min. The plasma cobalamin concentration was determined by competitive radioisotope binding technique. Results The maximal plasma cobalamin concentration (C-max) after nasal administration of 750 mu g hydroxocobalamin was 1900 +/- 900 pmol l(-1) (mean +/- s.d.). The maximal plasma cobalamin concentration was reached in 35 +/- 13 min (t(max)) The C-max after nasal administration of 1500 mu g hydroxocobalamin was 3500 +/- 2500 pmol l(-1) with a t(max) of 28 +/- 16 min. Both the AUC(0,240 min) and AUC(0,00) increased significantly with an increase of the dose from 750 mu g to 1500 mu g (P=0.037 and P=0.028, respectively). The nasal spray was well tolerated. No signs of irritation or local sensitivity were noted. Conclusions The nasal absorption of hydroxocobalamin in healthy elderly adults is rapid, high and well tolerated.