Peptide drug, properties

In addition, hydrophilic substances can be taken up into the membrane when complexes with hydrophobic counter-ions are formed. This property has been exploited for increasing the uptake of peptidic drugs by, for example, salicylate [157],... 

In recent studies both in vitro (Caco-2 cells) and in vivo in rats, TMC with a degree of trimethylation of 60% was proven to be an excellent intestinal absorption enhancer of the peptide drugs buserelin and octreotide. The observed absolute bioavailability values were 13 and 16% for buserelin and octreotide, respectively [83] (impublished data Fig. 5). Permeation enhancing effects were more responsible for these increased bioavailabilities, rather than the mucoadhesive properties of the TMC polymers. Nevertheless, mucoadhesion is a prerequisite for these polymers in order to further act as absorption enhancers. 

Peptide hormones and neurotransmitters are primary agents of communication between different cell types In the body of complex living systems Including man. Thus, analogs of natural peptide hormones and neurotransmitters with appropriate properties have exceptional potential as drugs. Despite this potential and the need for peptide drugs, development has been slow. Why ... 

Takeuchi H, Yamamoto H, Kawashima Y (2001) Mucoadhesive nanoparticulate systems for peptide drug delivery. Adv Drug Del Rev 47( 1 ) 39—54 Takeuchi H, Matsui Y, Yamamoto H, Kawashima Y (2003) Mucoadhesive properties of carbopol or chitosan-coated liposomes and their effectiveness in the oral administration of calcitonin to rats. J Control Rel 86(2-3) 235-242 Takeuchi H, Matsui Y, Sugihara H, Yamamoto H, Kawashima Y (2005a) Effectiveness of submicron-sized, chitosan-coated liposomes in oral administration of peptide drugs. Int J Pharm 303(1-2) 160-170... 

Oechslein, Fricker, and Kissel " studied various powder formulations of mucoadhesive polymers for their efficacy to increase the nasal absorption of octreotide in rats. Although chitosan showed the highest water uptake (chitosan > microcrystalline cellulose > semicrystalline cellulose > pectin = hydroxyethyl starch = alginic acid = Sephadex G25), the highest peptide drug bioavailability was found after coadministration of alginic acid and Sephadex G25 powders (4.1 and 5.56%, respectively). The authors concluded that the calcium-binding properties of the polymers used correlated better with the increased octreotide bioavailability. 

Samanen J. Physical biochemistry of peptide drugs structure, properties, and stabilities of peptides compared with proteins. In Peptide and Protein Drug Delivery. New York Marcel Dekker, 1991 137-166. 

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