Absorption Of Salmon Calcitonin Research Articles

Enhancement of Chemical Stability and Transdermal Absorption of Salmon Calcitonin Loaded in Elastic Niosomes

Enhancement of Chemical Stability and Transdermal Absorption of Salmon Calcitonin Loaded in Elastic Niosomes

Effects of proteolytic enzyme inhibitors as absorption enhancers on the transdermal iontophoretic delivery of calcitonin in rats.

The effects of proteolytic enzyme inhibitors, aprotinin, soybean trypsin inhibitor and camostat mesilate as absorption enhancers on the transdermal iontophoretic delivery of salmon calcitonin (SCT) have been examined in rats. The dermal absorption of SCT was evaluated with hypocalcaemic effect. Application of SCT (12.5 int. units/rat) onto abdominal skin did not produce any hypocalcaemic effect. This produced a small hypocalcaemic effect with cationic iontophoresis (drug phase, anode; reference phase, cathode; high frequency pulses of 1 V at 10 kHz, 2h). Furthermore, camostat mesilate (1 mM) and aprotinin (10(6) int. units mL-1) enhanced the hypocalcaemic effects on the application of SCT with iontophoresis. These hypocalcaemic effects were highest with the pH 4.0 preparation compared with those of the pH 5.5, pH 7.0 and pH 8.0 preparations. However, soybean trypsin inhibitor did not change the hypocalcaemic effects. This was because the soybean trypsin inhibitor is a relatively high molecular weight peptide (mol. wt 8000) and an anion at used pH, and therefore was not absorbed through rat skins with cation iontophoresis.

Influence of fillers in powder formulations containing N-acetyl- l-cysteine on nasal peptide absorption

We examined the influence of filler species on the nasal absorbability of peptide drugs via a newly developed powdery formulation system containing N-acetyl- l-cysteine (NAC) as an absorption enhancer. Using salmon calcitonin (SCT) as the principal model drug, we tested the effects of various formulations with different powder materials as fillers on the nasal absorption of SCT in rats. An intranasal administration experiment revealed that the use of less wettable powders provided better nasal absorbability, and the highest absolute bioavailability (30.0% ± 8.6%) was obtained when ethylcellulose was used as a filler. All these results were readily explicable in terms of our hypothetical enhancing mechanism. Furthermore, human parathyroid hormone and insulin were applied to this ethylcellulose formulation system, giving nasal bioavailabilities of 28.2% ± 6.5% and 23.4% ± 10.6%, respectively, thus suggesting that this formulation system is widely applicable to peptide drugs.

Absorption enhancement of poorly absorbed hydrophilic compounds from various mucosal sites by combination of mucolytic agent and non-ionic surfactant

Absorption enhancement of poorly absorbed hydrophilic compounds from various mucosal sites by co-administration of a mucolytic agent and a non-ionic surfactant was examined in rats. Fluorescein isothiocyanate-labeled dextran with average molecular weight of ca. 4.4 kDa (FD-4), and salmon calcitonin (SCT) were used as model compounds. N-acetylcysteine (NAC) and p- t-octyl phenol polyoxyethylene-9.5 (Triton X ®-100, TX-100) were selected as a mucolytic agent and a non-ionic surfactant, respectively. Dosing solutions containing these agents were administered into various mucosal sites including the nose, the lung and the large intestine, and the bioavailabilities were determined. The combination of 5% NAC and 5% TX-100 significantly enhanced the nasal, the pulmonary and the large intestinal absorption of FD-4 compared to the control, and the enhancement ratios relative to the control were 7.2-, 2.8- and 4.5-fold, respectively. The different enhancement ratio among the administration sites explored indicates that the absorption enhancing effect of the combination of NAC and TX-100 is site-dependent. This combination also improved the nasal and the pulmonary absorption of SCT, and the enhancement ratios relative to the control were 6.1- and 8.1-fold, respectively. All these results suggest that the combination strategy of a mucolytic agent and a non-ionic surfactant may be widely applicable to various mucosal deliveries of poorly absorbed hydrophilic compounds.

Synergistic absorption enhancement of salmon calcitonin and reversible mucosal injury by applying a mucolytic agent and a non-ionic surfactant

The present study investigated the intestinal absorption enhancement of salmon calcitonin (SCT) and the intestinal mucosal damage when a mucolytic agent and a non-ionic surfactant were administered simultaneously to rats. N-acetylcysteine (NAC) and p- t-octyl phenol polyoxyethylene-9.5 (Triton X ®-100, TX-100) were chosen as the model mucolytic agent and the non-ionic surfactant, respectively. Dosing solutions containing these agents were administered directly into the rat jejunum, and the bioavailability of SCT up to 2 h was determined. NAC and TX-100, when they were used alone at a dose of 1 mg/head, did not show the apparent enhancement compared to the control. However, simultaneous use of NAC and TX-100 enhanced the intestinal absorption of SCT in a synergistic manner, and absolute bioavailability increased 12.5-fold compared to the control. The effect of NAC and TX-100 on SCT absorption was not dependent on their doses over the range of 0.2–2 mg/head, and the maximum effect was obtained at a dose of 1 mg/head. Absorption enhancement of SCT by a combination of NAC and TX-100 was compared to those from the classical absorption enhancers. Absorption-enhancing ability of the combination of NAC and TX-100 was significantly higher than those of sodium deoxycholate, citrate, and the combination of citrate and taurocholate, and was comparable with that of the combination of citrate and taurodeoxycholate. Finally, the intestinal mucosal damage caused by the combination of NAC and TX-100 was assessed using a capsule device. Acute damage on intestinal mucosa was observed when they were exposed into rat intestine, but this morphological damage was found to be reversible. All these results suggest that simultaneous use of a mucolytic agent and a non-ionic surfactant would offer a potentiality for peroral delivery of peptide drugs like SCT.

In vitro and in vivo evaluation of the enhancing activity of glycyrrhizin on the intestinal absorption of drugs.

The enhancing activity of dipotassium glycyrrhizinate (Grz) on the intestinal absorption of drugs has been demonstrated in an in vitro study using Caco-2 cell monolayers and in an in vivo absorption study in rats. The hydrolysis of Grz by luminal content and mucosa of the rat colon was investigated. The absorption-enhancing activity of Grz and its hydrolysates was estimated by changes in transepithelial electrical resistance (TEER) and the permeation of sodium fluorescein (Flu-Na) in Caco-2 cell monolayers. It was further evaluated through the absorption of salmon calcitonin (sCT) in the rat colon. Grz was not hydrolyzed to glycyrrhetinylmonoglucuronide (GrMG) and glycyrrhetinic acid (GA) by colonic mucosa, but, rather by the beta-glucuronidase in colonic flora. The hydrolysis of Grz to GrMG was extremely slow and the GrMG produced was rapidly regenerated to GA. Grz and GrMG had no effect on TEER nor on the permeability of Flu-Na across Caco-2 cell monolayers. On the other hand, GA decreased TEER and increased the permeability of Flu-Na in a dose-dependent manner. However, Grz and GrMG enhanced the plasma calcium-lowering effect of sCT after administration in the rat colon. The coadministration of sCT and GA in the rat colon induced the strongest plasma calcium-lowering effect and the highest plasma concentration of sCT. The in vivo enhancing-activity of Grz in the absorption of drugs is dependent on GA, a hydrolysis product of Grz resulting from the action of beta-glucuronidase in intestinal flora.

The influence of the enhancer dimyristoylphosphatidylglycerol and formulation factors on the nasal absorption of salmon calcitonin

The objective of this investigation was to study the effect of the phospholipid dimyristoylphosphatidylglycerol (DMPG) on the intranasal absorption of the polypeptide salmon calcitonin (sCT). DMPG was included as an absorption enhancer for salmon calcitonin in a 0.03 M acetate buffer at pH 4 in a nasal spray formulation. The absorption of sCT was studied as a function of NaCl concentration from 0.045 to 0.3 M. Serum calcitonin was determined using a double-antibody radioimmunoassay (RIA). The presence of the phospholipid demonstrated a significant difference in the intranasal bioavailability of salmon calcitonin. The results showed that DMPG enhanced the nasal absorption of sCT by approximately twofold at a salt concentration of 0.045 M. However, higher salt concentrations in the formulation demonstrated a decrease in the absorption-enhancing effect of DMPG. The effect of DMPG on the calcium-lowering effect of sCT was also studied. There was no significant difference in the hypocalcemic activity of sCT in the presence of DMPG. In addition, it was found that increasing the viscosity of those formulations containing DMPG did not further increase the nasal bioavailability of sCT.

Absorption enhancement of calcitonin in the rat intestine by carbopol-containing submicron emulsions

The absorption of salmon calcitonin (sCT) in the jejunum and the colon of the rat from submicron emulsions with (MA SME) and without (SME) the adhesive polymer Carbopol®940 was studied in side-by-side diffusion cells and closed intestinal loops of the anesthetized rat. sCT permeated the jejunal and colonic mucosa of the rat at similar rates. However, when the sCT was introduced in MA-SME a profound enhancement (3.3-fold increase) in the diffusion rate was observed in the colon, but not in the jejunal epithelium. It was found that after intra-colonic administration, the SME formulations yielded a significant reduction in plasma Ca 2+ levels as compared to administration of sCT in normal saline. In the case of MA-SME, the reduction was more profound (80% of Ca 2+ of basal level at 120 min, as compared to 90% of Ca 2+ basal level at 15 min for MA-SME and SME, respectively) and was prolonged (1.5-fold) in the case of the MA-SME. Similarly, MA-SME caused a profound increase (14.7%) in the absolute bioavailability of sCT following intra-colonic administration in the rat. Indomethacin-containing MA-SME adhered rapidly, and at similar rates, to the mucosa of everted sacks taken from the jejunum or colon of the rat. It is suggested that enhancement of sCT absorption is attributable to both adherence of the emulsion droplets to the epithelium mucosa and the protease inhibition and absorption enhancement properties of Carbopol®940.

Enhancement of nasal salmon calcitonin absorption by lauroylcarnitine chloride in rats.

We investigated optimum formulation characteristics in the nasal absorption of salmon calcitonin (sCT) by incorporation of acylcarnitines. Nasal sCT formulations were administered to anesthetized rats. Plasma calcium level was measured and pharmacological bioavailability (P.bioav) was calculated. Nasal sCT absorption was significantly enhanced by carnitines with acyl groups of 12 or more carbon atoms. Enhancement by lauroylcarnitine chloride (LCC) was observed at its critical micelle concentration and reached a plateau at the concentration of 0.1 percent. Optimal absorption was achieved at a molar ratio of LCC to sCT of 5:1. Enhancement was not influenced by osmolarity and maximum enhancement was obtained at pHs 3.1 and 4.0. The 12-carbon LCC was the strongest enhancer among acylcarnitines. Micelle formation played a key role in this enhancement effect.

Effects of proteolytic enzyme inhibitors on nasal absorption of salmon calcitonin in rats

Proteolytic enzyme inhibitors were examined as absorption enhancers for the nasal absorption of salmon calcitonin (SCT) in rats. Bestatin, diprotinin, leupeptin, aprotinin, soybean trypsin inhibitor and camostat mesilate were used as enzyme inhibitors. The nasal absorption of SCT was evaluated by measuring its hypocalcemic effects. The peptidase activities of rat nasal mucosal tissue were high and found to be in the following order: leucine aminopeptidase (2.72 nmol/min per mg protein) > dipeptidyl aminopeptidase (1.84 nmol/min per mg protein) > cathepsin (650 pmol/min per mg protein) > trypsin.(4.61 pmol/min per mg protein). Nasal administration of SCT (10 IU/kg, pH 7.0) showed low pharmacological availability (3.2%). Coadministration with bestatin (aminopeptidase inhibitor, 0.0 1– 1 mM) or diprotinin A (dipeptidyl peptidase inhibitor, 0.1-1 mM) did not change the hypocalcemic effects. Coadministration with aprotinin (trypsin inhibitor, 10 3-10 4 KIU/ml), camostat mesilate (aminopeptidase and trypsin inhibitor, 0.1 – 10 mM) or leupeptin (trypsin and cathepsin B inhibitor, 0.1 – 1 mM) enhanced the hypocalcemic effects and, thus, the nasal absorption of SCT. The hypocalcemic effects of SCT at various pH values (pH 4.0, 7.0 and 8.0) with or without aprotinin were the highest at pH 4.0. The pharmacological availabilities after nasal administration of SCT (10 IU/kg) at pH 4.0 and 7.0 were increased from 5.4 to 7.5% and from 3.2 to 6.9% by aprotinin (10 4 KIU/ml), respectively. Therefore, inhibitors which have a trypsin inhibitory activity are useful for enhancing nasal absorption of SCT.

Study on pulmonary delivery of salmon calcitonin in rats: effects of protease inhibitors and absorption enhancers.

Effects of protease inhibitors and absorption enhancers on the absorption of salmon calcitonin (sCT) were evaluated after intratracheal coadministration to rats using the plasma Ca level as an index. Remarkable absorption enhancement could be attained with unsaturated fatty acids such as oleic acid and polyoxyethylene oleyl ether (absorption enhancers) and with chymostatin, bacitracin, potato carboxypeptidase inhibitor and phosphoramidon (protease inhibitors). sCT degrading enzymes had four times higher activity per total protein in membrane fraction of lung homogenates than the activity in cytosol fraction. These enzymes are thought to be serine proteases and metalloenzymes from the in vitro action profile of protease inhibitors. A good correlation between the in vitro activity of protease inhibitors and the in vivo enhancing effect on sCT activity suggested that membrane enzymes are responsible for the inactivation of sCT. Metabolic degradation and low permeability of sCT may be possible barriers to the absorption of sCT.