Time dependent effects of two absorption enhancers on the nasal absorption of growth hormone in rabbits

Effectiveness of pirotiodecane, absorption enhancer, on nasal absorption in rabbits

The absorption enhancing effect of 1-[2-(decylthio) ethyl] azacyclopentan-2-one (Pirotiodecane), on drug permeation across rabbit nasal mucosa was studied. The nasal epithelial mucosa was isolated from rabbit nasal septum and mounted in an Ussing chamber to allow for monitoring of the membrane resistance (Rm), and the permeation of fluorescein isothiocyanate-labeled dextran (FD-4, M.W. 4,400 Da). Treatment with 0.05, 0.1, and 0.2% Pirotiodecane for 60 min decreased Rm, and increased the cumulative amount of FD-4 permeated in a concentration-dependent manner, suggesting that Pirotiodecane possesses passively a disassembly of tight junction to enable the enhanced FD-4 permeation. The remarkable increase in plasma concentration of FD-4 was also observed in intranasal co-administration with 1% Pirotiodecane in rabbits. The Rm was virtually maintained after the removal of Pirotiodecane, although recovery of Rm was not seen. On the other hand, the increase in plasma concentration of FD-4 with intranasal co-administration of 1% Pirotiodecane in rabbits in vivo was not observed in FD-4 administration at 15-60 min after administration of 1% Pirotiodecane alone. It was concluded that Pirotiodecane possesses a relatively short absorption enhancing effect through nasal epithelial.

Alkanoylsucroses in nasal delivery of low molecular weight heparins: in-vivo absorption and reversibility studies in rats

The efficacy of alkanoylsucroses in enhancing nasal absorption of low molecular weight heparin (LMWH) and the time span of action of these agents on the nasal membrane has been investigated. In this regard, LMWH formulated with alkanoylsucroses was administered nasally to anaesthetized male Sprague-Dawley rats and the absorption of LMWH was determined by measuring plasma antifactor Xa activity. The duration of action of these agents at the site of administration was investigated by an in-vivo reversibility study. The potency and efficacy of dodecanoylsucrose was compared with that of sodium glycocholate. Alkanoylsucroses used in this study include dodecanoylsucrose, decanoylsucrose and octanoylsucrose. These agents enhance nasal absorption of enoxaparin in a dose-dependent and chain-length-dependent manner. Of the agents tested, dodecanoylsucrose was found to be the most potent in enhancing nasal absorption of LMWH. The bioavailability of enoxaparin formulated with alkanoylsucroses was increased by several folds compared with enoxaparin formulated in saline. The reversibility study with dodecanoylsucrose showed that the effect of alkanoylsucroses faded away with time and the duration of action of this agent at the site of administration was 120-140 min. Dodecanoylsucrose was found to be twice as potent as sodium glycocholate. Overall, the nasal absorption of LMWH was effectively enhanced by co-administration of alkanoylsucroses and the effect of alkanoylsucroses on nasal epithelium was found to be reversible. The potency of these agents depends on their hydrophobic chain lengths.

Nasal bioavailability of peptide T in rabbits: absorption enhancement by sodium glycocholate and glycofurol

The aim of the present study was to investigate the absolute nasal bioavailability of Peptide T from aqueous formulations containing sodium glycocholate, an absorption enhancer with known effect on epithelial tight junctions, and/or glycofurol in a crossover study in rabbits. Additionally, the reversibility of the absorption enhancing effect of sodium glycocholate was studied by applying enhancer and peptide T with different time intervals and calculating Area Under the Curve of the peptide in plasma. It was shown that the bioavailability of Peptide T was significantly enhanced when glycofurol or sodium glycocholate was added to a nasal formulation. The nasal bioavailability of Peptide T in water (control formulation), 5% glycofurol, 5% glycofurol+1% sodium glycocholate and 1% sodium glycocholate was 5.9, 22, 29 and 59%, respectively. As indicated by the differences in t(max), C(max) and time-concentration profiles different patterns of Peptide T absorption were seen from the vehicles containing glycofurol and sodium glycocholate. In the reversibility study, the enhancing effect of sodium glycocholate on nasal absorption of Peptide T was found to be reversible within 4 h. It was concluded, that nasal absorption of Peptide T in rabbits was effectively enhanced by co-administration of sodium glycocholate, which also provided very fast absorption rates as well as a relatively short lasting effect of the absorption enhancing effect. Co-administration of glycofurol leads to enhanced and prolonged absorption of the peptide. Combining the two enhancers did not lead to increased peptide T absorption compared to 5% glycofurol alone.