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

Research progress on the synthesis process, detection method, pharmacological effects and application of glycocholic acid

Objective

This review aims to summarize the research progress of glycocholic acid to promote its broader development and application.

Methods

This article collects relevant literature from databases such as Science Direct, PubMed, Web of Science, Google Scholar and CNKI from the establishment to 2024, systematically organizing and analyzing aspects of glycocholic acid including its physicochemical properties, synthesis and extraction techniques, detection methods, pharmacological effects, mechanisms of action, clinical research, and application as an excipient.

Results

Glycocholic acid, as a key conjugated component in bile acids, exhibits various pharmacological effects such as anti-inflammatory and antioxidant activities. Nevertheless, current research on glycocholic acid is insufficient, with synthesis techniques requiring improvement, limited application of detection technologies, and a need for in-depth exploration of its pharmacological mechanisms. Due to its amphiphilic molecular structure, glycocholic acid is primarily used as a pharmaceutical excipient.

Conclusion

This review summarizes the existing research on glycocholic acid, indicating that future research should strengthen work in this field, including improving synthesis processes and enhancing the sensitivity of detection technologies, to provide a scientific basis for the development of new formulations and drug combinations, thereby promoting the advancement of traditional Chinese medicine.

A comprehensive review of advanced nasal delivery: Specially insulin and calcitonin

Peptide drugs through nasal mucous membrane, such as insulin and calcitonin have been widely used in the medical field. There are always two sides to a coin. One side, intranasal drug delivery can imitate the secretion pattern in human body, having advantages of physiological structure and convenient use. Another side, the low permeability of nasal mucosa, protease environment and clearance effect of nasal cilia hinder the intranasal absorption of peptide drugs. Researchers have taken multiple means to achieve faster therapeutic concentration, lower management dose, and fewer side effects for better nasal preparations. To improve the peptide drugs absorption, various strategies had been explored via the nasal mucosa route. In this paper, we reviewed the achievements of 18 peptide drugs in the past decade about the perspectives of the efficacy, mechanism of enhancing intranasal absorption and safety. The most studies were insulin and calcitonin. As a result, absorption enhancers, nanoparticles (NPs) and bio-adhesive system are the most widely used. Among them, chitosan (CS), cell penetrating peptides (CPPs), tight junction modulators (TJMs), soft NPs and gel/hydrogel are the most promising strategies. Moreover, two or three strategies can be combined to prepare drug vectors. In addition, spray freeze dried (SFD), self-emulsifying nano-system (SEN), and intelligent glucose reaction drug delivery system are new research directions in the future.

Self-assembled phospholipid-based mixed micelles for improving the solubility, bioavailability and anticancer activity of lenvatinib

The clinical efficacy of lenvatinib (LFT) is limited by its poor aqueous solubility and low bioavailability. In this work, LFT-loaded soy phospholipid and sodium glycocholate mixed micelles (LFT-MMs) were prepared through classical co-precipitation. And it was served as an oral administration to address these shortcomings. The preparation conditions were optimized by single-factor experiments. The mass ratio of PC, SGC and LFT, and the species of dispersing media were proved to be decisive factors in controlling the properties of LFT-MMs. The optimal LFT-MMs presented prominent enhancement (500-fold) in LFT solubility, high encapsulation efficiency (87.6 %) as well as suitable stability (>1 month at 4 °C). The biocompatibility of LFT-MMs was estimated by in vitro serum stability measurement and hemolysis test. It showed that serum proteins hardly adhered to the surface of LFT-MMs, and insignificant hemolytic rate (<0.5 %) was observed at the micelles concentration below 1 mg/mL. Cytotoxicity test (MTT assay) was carried out to judge the in vitro antitumor activity. LFT-MMs showed an enhanced inhibitory activity against two main kinds of differentiated thyroid cancer cells over LFT and LFT Mesylate. To estimate the in vivo oral bioavailability of LFT-MMs, SD rats were used as animal model. Notably, the relative bioavailability of LFT-MMs compared with the original form of LFT was 176.7 %. These superior characteristics indicated that the mixed micelles are promising water-soluble formulations suitable for LFT oral delivery.

Drug Bioavailability Enhancing Agents of Natural Origin (Bioenhancers) that Modulate Drug Membrane Permeation and Pre-Systemic Metabolism

Many new chemical entities are discovered with high therapeutic potential, however, many of these compounds exhibit unfavorable pharmacokinetic properties due to poor solubility and/or poor membrane permeation characteristics. The latter is mainly due to the lipid-like barrier imposed by epithelial mucosal layers, which have to be crossed by drug molecules in order to exert a therapeutic effect. Another barrier is the pre-systemic metabolic degradation of drug molecules, mainly by cytochrome P450 enzymes located in the intestinal enterocytes and liver hepatocytes. Although the nasal, buccal and pulmonary routes of administration avoid the first-pass effect, they are still dependent on absorption of drug molecules across the mucosal surfaces to achieve systemic drug delivery. Bioenhancers (drug absorption enhancers of natural origin) have been identified that can increase the quantity of unchanged drug that appears in the systemic blood circulation by means of modulating membrane permeation and/or pre-systemic metabolism. The aim of this paper is to provide an overview of natural bioenhancers and their main mechanisms of action for the nasal, buccal, pulmonary and oral routes of drug administration. Poorly bioavailable drugs such as large, hydrophilic therapeutics are often administered by injections. Bioenhancers may potentially be used to benefit patients by making systemic delivery of these poorly bioavailable drugs possible via alternative routes of administration (i.e., oral, nasal, buccal or pulmonary routes of administration) and may also reduce dosages of small molecular drugs and thereby reduce treatment costs.

Intranasal melatonin nanoniosomes: pharmacokinetic, pharmacodynamics and toxicity studies

AIM

Intranasal melatonin encapsulated in nanosized niosomes was preclinically evaluated.

METHODOLOGY

A formula of melatonin niosomes (MN) was selected through physicochemical and cytotoxic data for pharmacokinetic, pharmacodynamics and toxicity studies in male Wistar rats.

RESULTS

Intranasal MN was bioequivalent to intravenous injection of melatonin, providing therapeutic level doses. Acute and subchronic toxicity screening showed no abnormal signs, symptoms or hematological effects in any animals. Transient nasal irritations with no inflammation were observed with intranasal MN, leading it to be categorized as relatively harmless.

CONCLUSION

The intranasal MN could deliver melatonin to the brain to induce sleep and provide delayed systemic circulation, relative to intravenous injection and also distribute to peripheral tissue.

Absorption-Enhancing Effects of Bile Salts

Bile salts are ionic amphiphilic compounds with a steroid skeleton. Among the most important physiological properties of bile salts are lipid transport by solubilization and transport of some drugs through hydrophobic barriers. Bile salts have been extensively studied to enhance transepithelial permeability for different marker molecules and drugs. They readily agglomerate at concentrations above their critical micelle concentration (CMC). The mechanism of absorption enhancement by bile salts appears to be complex. The aim of the present article was to review bile salt structure and their application as absorption enhancers and the probable mechanism for increasing permeation based on previous studies.

Niosomal carriers enhance oral bioavailability of carvedilol: effects of bile salt-enriched vesicles and carrier surface charge

Carvedilol (CRV) is an antihypertensive drug with both alpha and beta receptor blocking activity used to preclude angina and cardiac arrhythmias. To overcome the low, variable oral bioavailability of CRV, niosomal formulations were prepared and characterized: plain niosomes (without bile salts), bile salt-enriched niosomes (bilosomes containing various percentages of sodium cholate or sodium taurocholate), and charged niosomes (negative, containing dicetyl phosphate and positive, containing hexadecyl trimethyl ammonium bromide). All formulations were characterized in terms of encapsulation efficiency, size, zeta potential, release profile, stability, and morphology. Various formulations were administered orally to ten groups of Wistar rats (n=6 per group). The plasma levels of CRV were measured by a validated high-performance liquid chromatography (HPLC) method and pharmacokinetic properties of different formulations were characterized. Contribution of lymphatic transport to the oral bioavailability of niosomes was also investigated using a chylomicron flow-blocking approach. Of the bile salt-enriched vesicles examined, bilosomes containing 20% sodium cholate (F2) and 30% sodium taurocholate (F5) appeared to give the greatest enhancement of intestinal absorption. The relative bioavailability of F2 and F5 formulations to the suspension was estimated to be 1.84 and 1.64, respectively. With regard to charged niosomes, the peak plasma concentrations (C_max) of CRV for positively (F7) and negatively charged formulations (F10) were approximately 2.3- and 1.7-fold higher than after a suspension. Bioavailability studies also revealed a significant increase in extent of drug absorption from charged vesicles. Tissue histology revealed no signs of inflammation or damage. The study proved that the type and concentration of bile salts as well as carrier surface charge had great influences on oral bioavailability of niosomes. Blocking the lymphatic absorption pathway significantly reduced oral bioavailability of CRV niosomes. Overall twofold enhancement in bioavailability in comparison with drug suspension confers the potential of niosomes as suitable carriers for improved oral delivery of CRV.

Preparation and biocompatibility study of in situ forming polymer implants in rat brains

We describe the development of polymer implants that were designed to solidify once injected into rat brains. These implants comprised of glycofurol and copolymers of D: ,L: -lactide (LA), ε-caprolactone and poly(ethylene glycol) (PLECs). Scanning electron microscopy (SEM) and gel permeation chromatography (GPC) showed that the extent of implant degradation was increased with LA: content in copolymers. SEM analysis revealed the formation of porosity on implant surface as the degradation proceeds. PLEC with 19.3% mole of LA: was chosen to inject in rat brains at the volume of 10, 25 and 40 μl. Body weights, hematological and histopathological data of rats treated with implants were evaluated on day 3, 6, 14, 30 and 45 after the injection. Polymer solution at the injection volume of 10 μl were tolerated relatively well compared to those of 25 and 40 μl as confirmed by higher body weight and healing action (fibrosis tissue) 30 days after treatment. The results from this study suggest a possible application as drug delivery systems that can bypass the blood brain barrier.

Biocompatibility study of glycofurol in rat brains

Glycofurol (GF) has been used clinically as a solvent for parenteral drug delivery systems. However, the application and toxicity of GF in the brain have not been reported. This study was carried out to assess the systemic and neurologic reactions of GF in rats upon intracranial injection. Hematological and neuropathological assessments of rats were performed during the acute, subacute and chronic period after the injection. Injection of the GF solution (GF 25 μL + PBS 25 μL) into the brain cortex showed that it did not cause any deaths or clinical neurobehavioral abnormalities. At the same volume as phosphate-buffered saline (PBS) injection, it had mild effects on all hematological data and histopathology of brain tissues. Nevertheless, histomorphologic assessments of the brain tissues treated with PBS 70 μL revealed different tissue responses compared with those of 70 μL GF solution (30 μL + PBS 40 μL) where tissues around the administration site showed elevated polymorphonuclear leukocytes, macrophages and gliosis. These results demonstrated that the GF solution (GF 25 μL + PBS 25 μL) administration was well tolerated and caused minor inflammatory responses of cerebral cortex. This suggests possibilities of GF for drug delivery systems in the brain parenchymal tissues.

Cannabidiol bioavailability after nasal and transdermal application: effect of permeation enhancers

CONTEXT

The nonpsychoactive cannabinoid, cannabidiol (CBD), has great potential for the treatment of chronic and 'breakthrough' pain that may occur in certain conditions like cancer. To fulfill this goal, suitable noninvasive drug delivery systems need to be developed for CBD. Chronic pain relief can be best achieved through the transdermal route, whereas 'breakthrough' pain can be best alleviated with intranasal (IN) delivery. Combining IN and transdermal delivery for CBD may serve to provide patient needs-driven treatment in the form of a nonaddictive nonopioid therapy.

OBJECTIVE

Herein we have evaluated the IN and transdermal delivery of CBD with and without permeation enhancers.

MATERIALS AND METHODS

In vivo studies in rats and guinea pigs were carried out to assess nasal and transdermal permeation, respectively.

RESULTS

CBD was absorbed intranasally within 10 minutes with a bioavailability of 34-46%, except with 100% polyethylene glycol formulation in rats. Bioavailability did not improve with enhancers. The steady-state plasma concentration of CBD in guinea pigs after transdermal gel application was 6.3 +/- 2.1 ng/mL, which was attained at 15.5 +/- 11.7 hours. The achievement of a significant steady-state plasma concentration indicates that CBD is useful for chronic pain treatment through this route of administration. The steady-state concentration increased by 3.7-fold in the presence of enhancer. A good in vitro and in vivo correlation existed for transdermal studies.

CONCLUSION

The results of this study indicated that CBD could be successfully delivered through the IN and transdermal routes.

Permeation of losartan across human respiratory epithelium: an in vitro study with Calu-3 cells

The potential for nasal delivery of losartan, a drug with poor oral bioavailability, was investigated using Calu-3 cells. Epithelial permeation of the drug with or without dimethyl-beta-cyclodextrin (DM-beta-CD) and glycocholate was investigated. Possible transport mechanism of the compound and epithelial mucosal tolerance were screened. Reversibility of epithelial membrane perturbation was also investigated by measuring transepithelial electrical resistance (TEER) recovery over a 24-h period following drug formulation exposure. The permeability coefficient of losartan was 1.3 + or - 0.5 x 10(-6) cm s(-1). This flux was not significantly different from that of formulations containing DM-beta-CD (0.5 and 1.0%) or glycocholate (0.5%). However, the formulation with 1.0% glycocholate significantly increased losartan permeation 7-fold. Losartan flux across the cells was concentration-dependent. Serosal to mucosal permeation was significantly higher than mucosal to serosal permeation. Concentration-dependency, as well as polarity in transport indicated that the flux of the compound across Calu-3 cells was not limited to passive diffusion. Cells exposed to DM-beta-CD (0.5 and 1.0%) and glycocholate (0.5%) caused no significant change in TEER and mitochondrial dehydrogenase activity (MDH). The results of the study showed that losartan may be a suitable drug candidate for nasal delivery.

Intranasal delivery: physicochemical and therapeutic aspects

Interest in intranasal (IN) administration as a non-invasive route for drug delivery continues to grow rapidly. The nasal mucosa offers numerous benefits as a target issue for drug delivery, such as a large surface area for delivery, rapid drug onset, potential for central nervous system delivery, and no first-pass metabolism. A wide variety of therapeutic compounds can be delivered IN, including relatively large molecules such as peptides and proteins, particularly in the presence of permeation enhancers. The current review provides an in-depth discussion of therapeutic aspects of IN delivery including consideration of the intended indication, regimen, and patient population, as well as physicochemical properties of the drug itself. Case examples are provided to illustrate the utility of IN dosing. It is anticipated that the present review will prove useful for formulation scientists considering IN delivery as a delivery route.

In vitro formulation optimization of intranasal galantamine leading to enhanced bioavailability and reduced emetic response in vivo

The purpose of the current investigation was to optimize an intranasal (IN) galantamine (an acetylcholinesterase inhibitor used for treatment of Alzheimer's disease) formulation using an in vitro tissue model, to correlate those results to in vivo bioavailability, and to compare emetic response to oral dosing. A design-of-experiments (DOE) based formulation screening employing an in vitro tissue model of human nasal epithelium was used to assess drug permeability, tight junction modulation, and cellular toxicity. In vivo studies in rats compared pharmacokinetic (PK) profiles of different formulations dosed intranasally. Finally, studies in ferrets evaluated PK and gastrointestinal (GI) related side effects of oral compared to nasal dosage forms. Galantamine permeation was enhanced without increasing cytotoxicity. Pharmacokinetic testing in rats confirmed the improved drug bioavailability and demonstrated an in vitro-in vivo correlation. Compared to oral dosing, IN galantamine resulted in a dramatically lowered incidence of GI-related side effects, e.g., retching and emesis. These findings illustrate that IN delivery represents an attractive alternative to oral dosing for this important Alzheimer's disease therapeutic. To our knowledge, the data herein represent the first direct confirmation of reducing GI-related side effects for IN galantamine compared to oral dosing.

Improved nasal absorption of salmon calcitonin by powdery formulation with N-acetyl-L-cysteine as a mucolytic agent

To establish a new formulation technology for the nasal delivery of peptide and protein drugs, we examined whether a mucolytic agent, N-acetyl-L-cysteine (NAC), could enhance the nasal absorption of a powder form of salmon calcitonin, a model peptide drug. We used ethylcellulose as an inert water-insoluble excipient. Various test formulations were prepared, and the effects on nasal absorbability were evaluated in rats and dogs. The powder formulation with NAC gave significant nasal absorption of SCT in both animal models, with absolute bioavailabilities of 30.0% in rats and 24.9% in dogs. Also, nasal administration of this formulation gave a quicker absorption rate than subcutaneous administration of SCT. NAC may reduce nasal fluid viscocity and improve accessibility of the drug to the epithelial membrane. The powder SCT/NAC/ethylcellulose formulation did not induce irritation or histological damage to the nasal membrane in rabbits. These results suggest that this formulation technology may be widely applicable for the nasal delivery of peptide or protein drugs.

Therapeutic utility of a novel tight junction modulating peptide for enhancing intranasal drug delivery

Previously, a novel tight junction modulating (TJM) peptide was described affording a transient, reversible lowering of transepithelial electrical resistance (TER) in an in vitro model of nasal epithelial tissue. In the current report, this peptide has been further evaluated for utility as an excipient in transepithelial drug formulations. Chemical stability was optimal at neutral to acidic pH when stored at or below room temperature, conditions relevant to therapeutic formulations. The TJM peptide was tested in the in vitro tissue model for potential to enhance permeation of a low-molecular-weight (LMW) drug, namely the acetylcholinesterase inhibitor galantamine, as well as three peptides, salmon calcitonin, parathyroid hormone 1-34 (PTH(1-34)), and peptide YY 3-36 (PYY(3-36)). In all cases, the TJM peptide afforded a dramatic improvement in drug permeation across epithelial tissue. In addition, a formulation containing PYY(3-36) and TJM peptide was dosed intranasally in rabbits, resulting in a dramatic increase in bioavailability. The TJM peptide was as or more effective in enhancing PYY(3-36) permeation in vivo at a 1000-fold lower molar concentration compared to using LMW enhancers. Based on these in vitro and in vivo data, the novel TJM peptide represents a promising advancement in intranasal formulation development.

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.

Chain length-dependent effects of alkylmaltosides on nasal absorption of enoxaparin

The purpose of this study was to investigate whether the hydrophobic chain length of alkylmaltosides affects their efficacy as absorption promoters for nasally administered low-molecular-weight heparin and to study whether these agents enhance nasal absorption in a time-dependent manner without causing irreversible damage to the nasal epithelial membrane. For the nasal absorption studies, enoxaparin formulated with different alkylmaltosides was administered nasally to anesthetized rats and absorption of the drug was determined by measuring plasma anti-factor Xa activity. Reversibility studies were performed by administering enoxaparin at different time points after administration of alkylmaltosides. The AUC(0-360) for plasma anti-factor Xa-time curves increased with the increase in alkylmaltoside concentration in the formulations. Absolute and relative bioavailability of enoxaparin were increased by two-fold when the alkyl chain length of maltosides was increased from 8 to 14 carbons. Alkylmaltosides therefore increase nasal absorption of enoxaparin in a dose- and chain length-dependent manner. Of the alkylmaltosides tested, tetradecylmaltoside is the most potent enhancer of nasal absorption of enoxaparin. Longer chain alkylmaltosides produce a more prolonged effect on nasal mucosa compared with those with shorter alkyl chain.

Pulmonary absorption of insulin mediated by tetradecyl-beta-maltoside and dimethyl-beta-cyclodextrin

PURPOSE

To determine if tetradecyl-beta-maltoside (TDM) and dimethyl-beta-cyclodextrin (DMbetaCD) enhance pulmonary absorption of insulin and to investigate if they do so by a reversible action on respiratory epithelium.

METHODS

Insulin formulated with saline, TDM, or DMbetaCD was administered intratracheally, after laryngoscopic visualization, as a spray to anesthetized rats. Reversibility studies were conducted in intact rats by administering insulin at different time points after administration of TDM or DMbetaCD. The pharmacodynamics and pharmacokinetics of insulin formulations were assessed by measuring plasma glucose and plasma insulin concentrations.

RESULTS

When insulin formulated with increasing concentrations (0.06-0.25%) of TDM or DMbetaCD were administered to anesthetized rats, there was a concentration-dependent decrease in plasma glucose and increase in plasma insulin concentrations. The relative bioavailability of insulin formulations containing TDM was higher (0.34-0.84%) than that of formulations containing DMbetaCD (0.19-0.48%). When insulin was administered 120 min after an agent was administered, in the reversibility study, no significant change in plasma glucose and insulin levels occurred compared to control.

CONCLUSIONS

Both TDM and DMBCD enhance pulmonary absorption of insulin, with TDM being more efficacious than DMbetaCD in enhancing insulin absorption via pulmonary administration. The effects of TDM and DMbetaCD on respiratory epithelium are reversible, and the epithelium reestablishes its normal physiologic barrier 120 min after exposure to these agents.

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.

Absorption enhancers for nasal drug delivery

This paper describes the basic concepts for the transmucosal delivery of drugs, and in particular the use of the nasal route for delivery of challenging drugs such as polar low-molecular-weight drugs and peptides and proteins. Strategies for the exploitation of absorption enhancers for the improvement of nasal delivery are discussed, including consideration of mechanisms of action and the correlation between toxic effect and absorption enhancement. Selected enhancer systems, such as cyclodextrins, phospholipids, bioadhesive powder systems and chitosan, are discussed in detail. Examples of the use of these enhancers in preclinical and clinical studies are given. Methods for assessing irritancy and damage to the nasal membrane from the use of absorption enhancers are also described. Finally, the mucosal use of absorption enhancers (chitosan) for the improved nasal delivery of vaccines is reported with reference to recent phase I/II clinical studies.