Acid-forming amino acids, effect bioavailability

Acid-forming amino acids, effect on Ca bioavailability, 76... 

The nasal administration was shown to be an effective administration route for lipophilic active substances like fentanyl. Moreover, the nasal route has also been used for the systemic administration of small peptides like buserelin acetate, nafarelin acetate and desmopressin, aU of them containing ten or less amino acid residues. However, for these molecules the nasal route forms only a poor non-invasive alternative to injection, since the nasal bioavailability of these peptides is less than 3-5 %. 

Preformed niacin occurs in foods either as nicotinamide (niacinamide) or as the pyridine nucleotide coenzymes derived from it, or as nicotinic acid, without the amide nitrogen, which is the form known as niacin in North America. Both nicotinamide and nicotinic acid are equally effective as the vitamin, but in large doses they exert markedly different pharmacological effects, so it is important, at least in that context, to make and maintain the distinction. In addition to the preformed vitamin, an important in vivo precursor is the amino acid L-tryptophan, obtained from dietary protein. Because the human total niacin supply, and hence niacin status, depends on the dietary tryptophan supply as well as on the amount of preformed dietary niacin and its bioavailability, it has become the accepted practice to express niacin intakes as niacin equivalents, ... 

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