Ammonium Glycyrrhizinate Research Articles

Ethosomes for skin delivery of ammonium glycyrrhizinate: In vitro percutaneous permeation through human skin and in vivo anti-inflammatory activity on human volunteers

The aim of this work was the evaluation of various ethosomal suspensions made up of water, phospholipids and ethanol at various concentrations for their potential application in dermal administration of ammonium glycyrrhizinate, a useful drug for the treatment of various inflammatory-based skin diseases. Physicochemical characterization of ethosomes was carried out by photon correlation spectroscopy and freeze fracture electron microscopy. The percutaneous permeation of ammonium glycyrrhizinate/ethosomes was evaluated in vitro through human stratum corneum and epidermis membranes by using Franz's cells and compared with the permeation profiles of drug solutions either in water or in a water–ethanol mixture. Reflectance spectrophotometry was used as a non-invasive technique to evaluate the carrier toxicity, the drug permeation and the anti-inflammatory activity of ammonium glycyrrhizinate in a model of skin erythema in vivo on human volunteers. Ethosomal suspensions had mean sizes ranging from 350 nm to 100 nm as a function of ethanol and lecithin quantities, i.e., high amounts of ethanol and a low lecithin concentration provided ethosome suspensions with a mean size of ∼ 100 nm and a narrow size distribution. In vitro and in vivo experiments were carried out by using an ethosome formulation made up of ethanol 45% (v/v) and lecithin 2% (w/v). The ethosome suspension showed a very good skin tolerability in human volunteers, also when applied for a long period (48 h). Ethosomes elicited an increase of the in vitro percutaneous permeation of both methylnicotinate and ammonium glycyrrhizinate. Ethosomes were able to significantly enhance the anti-inflammatory activity of ammonium glycyrrhizinate compared to the ethanolic or aqueous solutions of this drug. Some in vivo experiments also showed the ability of ethosome to ensure a skin accumulation and a sustained release of the ammonium glycyrrhizinate.

Chitosan nanoparticles as a novel delivery system for ammonium glycyrrhizinate

The ammonium glycyrrhizinate-loaded chitosan nanoparticles were prepared by ionic gelation of chitosan with tripolyphosphate anions (TPP). The particle size and zeta potential of nanoparticles were determined, respectively, by dynamic light scattering (DLS) and a zeta potential analyzer. The effects, including chitosan molecular weight, chitosan concentration, ammonium glycyrrhizinate concentration and polyethylene glycol (PEG) on the physicochemical properties of the nanoparticles were studied. These nanoparticles have ammonium glycyrrhizinate loading efficiency. The encapsulation efficiency decreased with the increase of ammonium glycyrrhizinate concentration and chitosan concentration. The introduction of PEG can decrease significantly the positive charge of particle surface. These studies showed that chitosan can complex TPP to form stable cationic nanoparticles for subsequent ammonium glycyrrhizinate loading.

COMPARISON OF NASAL INSULIN POWDERS PREPARED BY SUPERCRITICAL FLUID AND FREEZE-DRYING TECHNIQUES

ABSTRACT In this study, the effect of drug loading on the nasal absorption of insulin was determined. Human insulin was loaded into different drug carriers by two methods: supercritical fluid processing and freeze-drying. The powder formulations were characterized and then evaluated after nasal administration to alloxan induced diabetic rabbits at a dose of 5U/kg and 7.5U/kg. The blood glucose levels and serum insulin levels were monitored for five hours after administration of insulin formulations. The drug carriers evaluated were: ammonium glycyrrhizinate (AG), polyacrylic acid (PAA), cross-linked polyacrylic acid (CPAA), polyethylene oxide (PEO) and chitosan (CHTN). Nasal administration of AG infused with insulin by carbon dioxide resulted in absolute bioavailability of 9.81% as compared to 2.86% observed with same powder loaded with insulin by freeze-drying. 8.05% bioavailability was obtained with PAA powder loaded with insulin by carbon dioxide as compared to much lower absorption seen with freeze-dried formulation. Similarly a two fold increase in absolute bioavailability was observed when carbon dioxide infused CPAA powder formulation was compared to the lyophilized powder. Nasal administration of PEO and CHTN loaded with insulin by carbon dioxide resulted in bioavailabilities of 1.55% and 1. 18% respectively. The drug-loading process seems to have a significant effect on nasal absorption of insulin. The powders loaded with insulin by carbon dioxide infusion resulted in significantly higher absorption. The exact mechanism is still not known and a possible explanation for increased absorption may be due to improved stability of insulin in carbon dioxide infused formulations. Among the powders evaluated, polyacrylic acid and ammonium glycyrrhizinate prepared by carbon dioxide infusion as drug-loading method seem to offer good potential for development of nasal powder dosage forms for insulin.

In vivo evaluation of spray formulations of human insulin for nasal delivery

There are many ongoing investigations to improve the nasal bioavailability of peptide and protein formulations. The presence of bioadhesive polymers in nasal formulations may increase the residence time of the drugs in the nasal cavity. A combination of bioadhesive polymers with permeation enhancers would seem to further improve nasal bioavailability. In this study, insulin spray formulations containing two bioadhesive polymers (1.5% w/v microcrystalline cellulose (MCC) and 70% w/w Plastoid L50) alone or in combination with the enhancers such as sodium taurocholate (ST), ammonium glycyrrhizinate (AG) or glycyrrhetinic acid (GA) at 1% w/v level, were evaluated in diabetic rabbits. A total volume of 100 μl of freshly prepared insulin formulation was sprayed into the nasal cavity of each diabetic rabbit. Glucose levels were monitored using a blood glucose assay and serum insulin levels were analyzed using RIA. 5 U/kg insulin in the MCC suspension alone resulted in an absolute bioavailability of 1.96% while Plastoid L50 alone resulted in 2.25% absolute bioavailability. Insulin in the MCC suspension and ST, AG or GA resulted in 8.36, 7.83 and 2.15% bioavailability, respectively. The same formulations produced a hypoglycemic effect in terms of total glucose reductions of 39.12, 15.96 and 9.36% and the maximal decreases in glucose levels were 58.37, 21.8 and 18.61%, respectively. The Plastoid formulation containing 1% ST provided nasal insulin bioavailability of 5.9% with a total glucose reduction of 17.03% and a maximal glucose decrease of 26.56%. Insulin spray formulations containing 1% ST alone and 1% AG alone resulted in bioavailabilities of 7.25 and 3.57%, respectively. These same sprays provided total glucose reductions of 25.08 and 16.97% with maximal glucose decreases of 44.56 and 19.81%, respectively. The presence of benzalkonium chloride and 2-phenylethanol as preservatives in the MCC suspension resulted in higher insulin absorption than the same formulation without preservatives (6.31% vs 1.96%).

Ammonium glycyrrhizinate (AMGZ) effects on membrane integrity

Potential mechanisms by which ammonium glycyrrhizinate (AMGZ) modifies biomembranes and promotes transcellular permeation of low molecular weight markers were investigated. The effects of increasing AMGZ concentration, pH, and ionic strength on erythrocyte hemolysis and on the steady-state fluorescence anisotropy, r, of fluorophore-labeled tracheal and erythrocyte ghost membranes were studied. At AMGZ concentrations greater than 1%, significant hemolytic activity was observed. Hemolysis was not observed over either the pH or the ionic strength ranges produced by corresponding concentrations of AMGZ. A significant decrease in r, a measure of lipid packing order, was observed in erythrocyte ghost membranes at AMGZ concentrations greater than 0.5 and 1.0% AMGZ in both lipid-water interfaces labeled with 1-[4-(trimethylammonio)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) and core lipid domains labeled with 1,6-diphenyl-1,3,5-hexatriene (DPH), respectively. Fluorescence lifetime studies indicated that the DPH and TMA-DPH probes were to some degree sensitive to AMGZ and suggested the possibility of some contributions of direct AMGZ: probe interaction to interpretation of the fluorescence studies. A significant decrease in lipid packing order was also observed predominantly at the lipid-water interace of apical trachéal cell membranes at AMGZ concentrations greater than 0.5%. The lipid packing order for bovine trachea apical membranes and erythrocyte ghosts was not affected by varied pH or ionic strength produced by corresponding AMGZ additions. Collectively, results suggested that direct effects of AMGZ, as opposed to accompanying pH or ionic strength changes, on primarily membrane components at the lipid-water interface may contribute to alterations in membrane permeability to low molecular weight substances.

Lack of effect of ammonium glycyrrhizinate on the morphology of ovine nasal mucosa in vitro.

Glycyrrhetinic acid derivatives are reported to be nasal absorption promoters (1). Effects of ammonium glycyrrhizinate (AMGZ) on the in vitro morphology of ovine nasal mucosa were therefore examined by light and electron microscopy. Nasal mucosa was stripped from the submucosa and mounted in Ussing chambers. Exposure of the apical surface to 2% ammonium glycyrrhizinate (24 mM) for 90 min caused no histopathological changes to the nasal epithelium. Epithelial integrity remained intact as evidenced by the continued presence of morphologically intact junctional complexes. No sloughing of the epithelial layer from the basement membrane was observed, and cilia and microvilli were not affected by treatment with AMGZ. The results indicate that short-term exposure in vitro to ammonium glycyrrhizinate caused no overt morphological damage to ovine nasal mucosa.

In vitro nasal transport across ovine mucosa: effects of ammonium glycyrrhizinate on electrical properties and permeability of growth hormone releasing peptide, mannitol, and lucifer yellow.

Transport of growth hormone releasing peptide across ovine nasal mucosa in the absence or presence of ammonium glycyrrhizinate (AMGZ) was studied in vitro. Ovine nasal mucosa was stripped from underlying cartilage and mounted in Ussing chambers. Transepithelial conductance (Gt) and short-circuit current (Isc) were monitored during experiments to assess tissue viability and integrity. Radiolabeled mannitol (Man; MW 182) and growth hormone releasing peptide (GHRP, SK&F 110679; MW 873) were employed to measure transport rates across the epithelium, and fluorescence spectroscopy was employed to measure rates of lucifer yellow (LY; MW 521) transport. Effects of AMGZ on ovine nasal mucosal viability and transport were determined from changes in electrical properties of fluxes of [3H]GHRP, [3H]Man, and LY. Results demonstrate that electrical properties of ovine nasal mucosa are stable over the time course of the experiments (Gt = 8.3 +/- 0.5 mS/cm2 and Isc = 3.7 +/- 0.2 microEq/hr.cm2; n = 21). Man fluxes were comparable in the mucosal (m)-to-serosal (s) and s-to-m directions [0.10 +/- 0.01 (n = 17) and 0.10 +/- 0.01 (n = 4) %/hr.cm2, respectively]. Transport of GHRP and LY in the m-s direction was similar to that of Man [0.08 +/- 0.01 (n = 11) and 0.09 +/- 0.01 (n = 3) %/hr.cm2, respectively]. GHRP flux was equivalent in the m-s and s-m directions. GHRP did not significantly alter ion transport processes as indicated by the lack of any change in Gt or Isc.(ABSTRACT TRUNCATED AT 250 WORDS)

Topical Tolerability of Calcitonin Nasal Preparation, its Excipients and Sodium Taurocholate Studied by SEM and Mucociliary Transport Velocity

In addition to the active drugs, intranasal preparations contain various excipients and preservatives to stabilise the formulation and prevent the growth of contaminating microorganisms during repeated use. This study assessed the topical tolerability of 1–7 Asu eel and salmon calcitonin, the excipients ammonium glycyrrhizinate, methyl and propyl p-hydroxybenzoate and benzalkonium chloride, and sodium taurocholate, which is used in other preparations to promote absorption. The ex vivo frog palate preparation was used to measure mucociliary transport velocity (MTV) as an index of their effects. In addition, scanning electron microscopy (SEM) was used to study the morphology of the mucosal surface of the palate before and after contact with the test substances. Frog Ringer’s solution, 1–7 Asu eel and salmon calcitonin did not significantly change MTV, confirming good tolerability by ciliated epithelium. The same was true for 0.5 and 2% ammonium glycyrrhizinate and 0.01% benzalkonium chloride, while p-hydroxybenzoates produced a small though significant reduction in MTV. Sodium taurocholate, however, led to a significant reduction in MTV for the palate with and without mucus. SEM studies confirmed the results, clearly identifying the damage to epithelial ciliated cells produced by sodium taurocholate.

Teratogenicity study of ammonium glycyrrhizinate in the Sprague-Dawley rat

Ammonium glycyrrhizinate (AG), a commercially used salt of glycyrrhizic acid, was administered in the drinking-water to Sprague-Dawley rats on days 7–17 of pregnancy. The actual intakes were 0, 21.33 ± 1.22, 238.75 ± 17.50 and 679.94 ± 69.87 mg AG/kg body weight/day for groups 0, 1, 2 and 3, respectively. AG caused polydipsia in the dams. Foetuses from the treated litters did not present an increase in external malformations, a decrease in weight or a decrease in the degree of ossification. However, there was a slight but significant increase in embryolethality and in the prevalence of external haemorrhages. Skeletal examination revealed a dose-related increase in minor anomalies, especially in the sternebral variants. Renal ectopy also increased significantly at the highest dose. These results indicate that the possible embryotoxicity of aromatizing compounds should be considered.

Quantitative Determination of Ammonium Glycyrrhizinate by Gas-Liquid Chromatography: Collaborative Study

Abstract Six samples of carbonated beverage were spiked at levels from 0 to 400 p pm with foodgrade ammonium glycyrrhizinate and sent to 7 participating laboratories for collaborative study. To facilitate the analysis of samples containing microquantities of ammonium glycyrrhizinate, slight modifications were made in the published GLC method. Recoveries of ammon ium glycyrrhizinate were 116.4, 102.0, 93.4, 102.3, and 105.8% for 35, 100, 200, 300, and 400 ppm levels, respectively. The method has been adopted as official first action.

Quantitation of Ammonium Glycyrrhizinate by Gas-Liquid Chromatography of the Silyl Ether Ester Derivative of the Aglycone

Abstract GLC method has been developed for the quantitation of ammonium glycyrrhizinate as the aglycone, glycyrrhetic acid. The aglycone is freed from the sugar moiety in a dioxanewater mixture, using a well established acid hydrolysis procedure. The hydrolysate is extracted with chloroform, an aliquot is dried on a steam bath, and the residue is treated with pyridine - trimethylchlorosilane - N,0 - bis (trimethylsilyl)acetamide reagent. The reacted product and internal standard are then chromatographed on a column of 1.5% OV-1 on Gas Chrom Q. Recoveries from both water and sodas containing caramel averaged 87%.