Normal and promoted gastrointestinal absorption of water-soluble substances. I. Induced rapidly reversible hyperabsorptive state in the canine fundic stomach pouch

Inhalable Formulations to Treat Non-Small Cell Lung Cancer (NSCLC): Recent Therapies and Developments

Cancer has been the leading cause of mortalities, with lung cancer contributing 18% to overall deaths. Non-small cell lung cancer (NSCLC) accounts for about 85% of all lung cancers. The primary form of therapy used to treat lung cancer still includes oral and systemic administration of drugs, radiotherapy, or chemotherapy. Some patients have to go through a regime of combination therapy. Despite being the only available form of therapy, their use is limited due to the adverse effects, toxicity, and development of resistance over prolonged use. This led to a shift and progressive evolution into using pulmonary drug delivery systems. Being a non-invasive method of drug-administration and allowing localized delivery of drugs to cancer cells, inhalable drug delivery systems can lead to lower dosing and fewer systemic toxicities over other conventional routes. In this way, we can increase the actual local concentration of the drug in lungs, which will ultimately lead to better antitumor therapy. Nano-based systems also provide additional diagnostic advantages during lung cancer treatment, including imaging, screening, and tracking. Regardless of the advantages, pulmonary delivery is still in the early stages of development and various factors such as pharmacology, immunology, and toxicology should be taken into consideration for the development of suitable inhalable nano-based chemotherapeutic drugs. They face numerous physiological barriers such as lung retention and efficacy, and could also lead to toxicity due to prolonged exposure. Nano-carriers with a sustained drug release mechanism could help in overcoming these challenges. This review article will focus on the various inhalable formulations for targeted drug delivery, including nano-based delivery systems such as lipids, liposome, polymeric and inorganic nanocarriers, micelles, microparticles and nanoaggregates for lung cancer treatment. Various devices used in pulmonary drug delivery loaded on various nano-carriers are also discussed in detail.

Regulatory status quo and prospects for biosurfactants in pharmaceutical applications

The concept of going 'green' and 'cold' has led to utilizing renewable resources for the synthesis of microbial biosurfactants that are both patient and eco-friendly. In this review, we shed light on the potential and regulatory aspects of biosurfactants in pharmaceutical applications and how they can significantly contribute to novel concepts for the Coronavirus 2019 (COVID-19) vaccine and future treatment. We emphasize that more specific guidelines should be formulated to regulate the approval of biosurfactants for human use. It is also crucial to implement a risk-based approach from the early research and development (R&D) phase in addition to establishing more robust standardized techniques and assays to evaluate the characteristics of biosurfactants.

Micelles entrapped microparticles technology: a novel approach to resolve dissolution and bioavailability problems of poorly water soluble drugs

Aim: Aim of this study was to design a solid oral delivery system for a weakly basic drug such as dasatinib (DAS), so as to achieve pH-independent dissolution and improved oral bioavailability.Methods: DAS was solubilised using sodium lauryl sulphate as an aqueous micellar system and such a system containing lactose monohydrate as carrier was spray-dried to obtain a solid mass. Subsequently, the DAS-solid was converted into a tablet using conventional tableting methods.Results: The dissolution study revealed pH-independent dissolution over a wide range of pH conditions. An in vivo bioavailability testing on rats revealed an improved C_max and AUC_0-24. Similarly, viability assay showed a better inhibitory effect of spray-dried dasatinib over the DAS.Conclusions: Micellar solubilisation and spray-drying technology can be approached to resolve poor dissolution and bioavailability of drugs belonging to biopharmaceutical classification system II and III. This technology is amenable to scale-up and has commercial potential.

Intestinal permeation enhancers for oral peptide delivery

Intestinal permeation enhancers (PEs) are one of the most widely tested strategies to improve oral delivery of therapeutic peptides. This article assesses the intestinal permeation enhancement action of over 250 PEs that have been tested in intestinal delivery models. In depth analysis of pre-clinical data is presented for PEs as components of proprietary delivery systems that have progressed to clinical trials. Given the importance of co-presentation of sufficiently high concentrations of PE and peptide at the small intestinal epithelium, there is an emphasis on studies where PEs have been formulated with poorly permeable molecules in solid dosage forms and lipoidal dispersions.

Antioxidant activity of Tween-20 and Tween-80 evaluated through different in-vitro tests

Objectives

This study aimed to evaluate the possible antioxidant activity of Tween-20 and Tween-80, two amphipathic nonionic surfactants commonly used as solubilizers and stabilizers, whose pharmacological effects have been ignored to a large degree.

Methods

Antioxidant activity was investigated in vitro measuring the scavenging activity on the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH●), the production of reactive oxygen species (ROS) in activated human neutrophils using flow cytometry and the myeloperoxidase (MPO) inhibitory activity.

Key findings

Tween-20 and Tween-80 did not show scavenging activity on DPPH●, while produced a decrease of the ROS production in human neutrophils, being Tween-20 more active than Tween-80. Moreover, Tween-80 and Tween-20 were found to significantly stimulate MPO enzymatic activity.

Conclusions

Our findings raise concerns with regard to the indiscriminate use of Tween-20 and Tween-80 in clinical and laboratory testing, since they could influence the results that are assigned to the tested substance.

Surfactant-based drug delivery systems for treating drug-resistant lung cancer

Among all cancers, lung cancer is the major cause of deaths. Lung cancer can be categorized into two classes for prognostic and treatment purposes: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Both categories of cancer are resistant to certain drugs. Various mechanisms behind drug resistance are over-expression of superficial membrane proteins [glycoprotein (P-gp)], lung resistance-associated proteins, aberration of the intracellular enzyme system, enhancement of the cell repair system and deregulation of cell apoptosis. Structure-performance relationships and chemical compatibility are consequently major fundamentals in surfactant-based formulations, with the intention that a great deal investigation is committed to this region. With the purpose to understand the potential of P-gp in transportation of anti-tumor drugs to cancer cells with much effectiveness and specificity, several surfactant-based delivery systems have been developed which may include microspheres, nanosized drug carriers (nanoparticles, nanoemulsions, stealth liposomes, nanogels, polymer-drug conjugates), novel powders, hydrogels and mixed micellar systems intended for systemic and/or localized delivery.

Strategies to address low drug solubility in discovery and development

Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.

Toxicity Profile of Solvents by Aspiration Approach for Topical Agent Delivery to Respiratory Tract Epithelium

Agent solubility is a problem for aspiration of agents into lungs for chemopreventive efficacy evaluation, since many agents have to be dissolved in solvents. These solvents may be toxic to the lung epithelium. A study was conducted in female A/J mice to determine toxicity of different solvent concentrations by using saline, dimethyl sulfoxide (DMSO), ethanol, polyethylene glycol 400 (PEG-400), and labrasol for 1, 5, and 28 days via aspiration route. Toxicity was determined by measuring changes in body weight and bronchoalveolar lavage fluid (BALF). No significant difference was observed in body weight, differential cell counts, lactate dehydrogenase (LDH) and total protein in all solvent groups compared to saline by 28 days except 50% ethanol. However, myeloperoxidase (MPO) and macrophage inflammatory protein-2 (MIP-2) showed significant increase in 2% and 10% DMSO, 10% ethanol, 0.1% and 2% PEG-400, and 1% labrasol by longer dosing. All solvents except for 10% ethanol and 2% PEG-400 are suitable for agent aspiration.

Effect of surfactants and pH on naltrexone (NTX) permeation across buccal mucosa

The objective of this pre-formulation study was to systematically investigate the effects of two surfactants (Brij 58(®) and Tween 80(®)) and change in solution pH on in vitro permeation of naltrexone HCl (NTX-HCl) across tissue engineered human buccal mucosa. For the study, 10mg/ml solutions of Tween 80(®) (0.1 and 1%, w/v) and Brij 58(®) (1%, w/v) were prepared in standard artificial saliva buffer solution (pH 6.8). For studying pH effects, solution pH was adjusted to either 7.5 or 8.2. As controls, three concentrations of NTX-HCl (2.5, 10 and 25mg/ml) were prepared. Using NTX standard solution (10mg/ml; pH 6.8), the permeation was observed between in vitro human and ex vivo porcine mucosa. It was observed that Brij 58(®) increased the permeation rates of NTX significantly. The flux of 10mg/ml solution (pH 6.8) increased from 1.9 ± 0.6 (× 10(2)) to 13.9 ± 2.2 (× 10(2))μg/(cm(2)h) (approximately 6-fold) in presence of 1% Brij 58(®). Increasing pH of NTX-HCl solution was found to increase the drug flux from 1.9 ± 0.6 (× 10(2)) (pH 6.8) to 3.0 ± 0.6 (× 10(2)) (pH 7.4) and 8.0 ± 3.5 (× 10(2)) (pH 8.2)μg/(cm(2)h), respectively. Histological analyses exhibited no tissue damage due to exposure of buccal tissue to Brij 58(®). The mean permeability coefficients (K(p)) for 2.5, 10 and 25mg/ml solutions of NTX-HCl (pH 6.8) were 5.0 (× 10(-2)), 1.8 (× 10(-2)) and 3.2 (× 10(-2))cm/h, respectively, consistent with data from published literature sources. Increase of NTX flux observed with 1% Brij 58(®) solution may be due to the effects of ATP. Increase in flux and the shortening of lag time observed by increasing in solution pH confirmed earlier finding that distribution coefficient (logD) of NTX is significantly affected by small increments in pH value and therefore plays an important role in NTX permeation by allowing faster diffusion across tissue engineered human buccal tissue.

Effects of nonionic surfactants on membrane transporters in Caco-2 cell monolayers

The objectives of this study were (1) to investigate the transporter inhibition activity of three nonionic surfactants on P-glycoprotein, the human intestinal peptide transporter, and the monocarboxylic acid transporter in Caco-2 cell monolayers, and (2) to evaluate the role of membrane fluidity and protein kinase C in surfactant-induced transporter inhibition. All three surfactants inhibited P-glycoprotein (P-gp). Over a range from 0 to 1 mM, Tween 80 and Cremophor EL increased apical-to-basolateral permeability (AP-BL) and decreased basolateral-to-apical (BL-AP) permeability of the P-gp substrate rhodamine 123. Vitamin E TPGS's effect was equally large, but essentially only reduced the BL-AP permeability of rhodamine 123, and did so at a vitamin E TPGS concentration of only 0.025 mM. These P-gp inhibition effects would appear to be related to these excipients' modulation of membrane fluidity, where Tween 80 and Cremophor EL fluidized cell lipid bilayers, while vitamin E TPGS rigidized lipid bilayers. However, among the three surfactants, only Tween 80 inhibited the peptide transporter, as measured by glycyl sarcosine permeability. Likewise, only Cremophor EL inhibited the monocarboxylic acid transporter, as measured by benzoic acid permeability. Nevertheless, at least one of these three surfactants inhibited each P-gp, the human intestinal peptide transporter, and the monocarboxylic acid transporter. A common functional feature of these three surfactants was their ability to modulate fluidity, although results indicate that even strong membrane fluidity modulation alone was not sufficient to reduce transporter activity. N-octyl glucoside, a nonionic surfactant that did not modulate membrane fluidity, did not affect transporter functioning. Protein kinase C inhibitors failed to affect rhodamine 123 and glycyl sarcosine permeability, suggesting protein kinase C inhibition was not the mechanism of transporter inhibition. These results suggest that surfactants can inhibit multiple transporters but that changes in membrane fluidity may not be a generalized mechanism to reduce transporter activity.

Modification of ceftibuten transport by the addition of non-ionic surfactants

The effects of non-ionic surfactants on the carrier-mediated transport of ceftibuten by rat intestinal brush-border membrane vesicles (BBMVs) were investigated. Ceftibuten uptake by BBMVs was measured by a rapid filtration technique. The concentration of surfactants for the uptake experiments was determined by a decrease in the turbidity of BBMV suspension and by the release of an impermeable probe, 2',7'-bis(carboxyethyl)-4(5)-carboxyfluorescein, from the vesicle inside. In fact, the surfactant concentration of 0. 03% (w/v) was selected to maintain the stability of BBMVs. The extent of ceftibuten uptake by BBMVs with various surfactants was correlated with their physicochemical properties, i.e. hydrophile-lipophile balance (HLB), critical micelle concentration (c.m.c.), average diameter of micelle colloid, and polydispersity determined by particle size distribution. The surfactants used were divided into two groups on the basis of polydispersity index (d(w)/d(n)), i.e. low polydispersity (d(w)/d(n) congruent with1) and high polydispersity d(w)/d(n)2). The ceftibuten uptake due to the addition of surfactants with low polydispersity increased with a decrease in the HLB number. These results indicate that the ceftibuten transport is modulated by the size distribution and hydrophobicity of surfactants. In addition, the effects of surfactants on the membrane lipid fluidity monitored by diphenylhexatriene (DPH) and trimethylammonium diphenylhexatriene (TMA-DPH) were investigated. There was significant correlation between ceftibuten uptake and the fluorescence anisotropy of TMA-DPH-labeled membranes due to the addition of surfactants with low polydispersity (r=-0.81, P<0.0001). These results suggest that surfactants with low polydispersity, in part, increase or decrease the outer membrane leaflet, thereby enhancing or suppressing the ceftibuten transport by BBMVs, and that ceftibuten transport caused by surfactants with low polydispersity may be strongly dependent on the hydrophobic interaction.

Enteral absorption of octreotide: absorption enhancement by polyoxyethylene-24-cholesterol ether

1. The somatostatin octapeptide-analogue octreotide was absorbed as an intact peptide from the gastro-intestinal tract with an absolute bioavailability of about 0.3% in rats. Administration of octreotide in the presence of polyoxyethylene (24)-cholesterol-ether (POECE) resulted in an about 23 fold increase of bioavailability. 2. In vitro studies with Caco-2 cells showed a dose-dependent increase in octreotide permeation with increasing doses of coadministered POECE. The use of [3H]-polyethyleneglycol (PEG) 4000 as an extracellular marker also indicated that higher doses of POECE may partly enhance paracellular transport of macromolecules. 3. By means of fluorescence microscopy it was shown that transepithelial transport of the fluorescent octreotide analogue (4-nitrobenzo-2-oxa-1,3-diazol [NBD] labelled octreotide) was enhanced by the addition of POECE. Besides an increased enterocyte uptake, there was evidence of enhanced partition of NBD-octreotide into the intercellular space between enterocytes after co-administration of POECE. In addition, there appeared to be changes in the hepatic topographic disposition of NBD-octreotide when it was given together with POECE compared with its administration alone. 4. In a study in healthy volunteers, 16 mg POECE significantly enhanced by 8 fold the absorption of octreotide after oral administration.

The effect of sodium deoxycholate given by gavage with heparin on the histology of the intestinal mucosa of the rat

To gain direct insight into the mechanism of sodium deoxycholate (DOC)-induced enhancement of gastroenteral heparin absorption in rats, we performed light and electron microscopic examination of the mucosa of the small intestine of animals treated orally with DOC, heparin or DOC plus heparin. The sole morphological change observed after DOC and DOC plus heparin administration was a marked reduction in the length and distribution of glycocalyx filaments on the microvilli of epithelial cells. The morphological picture had reverted to normal after 24 h, when the promotion of enteral heparin absorption by DOC is greatly reduced. Thus, we suggest that DOC may promote the enteral absorption of heparin in rats by affecting some as yet unidentified barrier mechanism requiring glycocalyx integrity.

Acid-catalyzed hydrolysis of sodium dodecyl sulfate

The acid-catalyzed hydrolysis of sodium dodecyl sulfate (1) and the effect of 1-dodecanol (2) on this hydrolysis were investigated. The rate of hydrolysis was followed by measuring the rate of production of HSO-4 using a pH-stat. The rate constant (kH+) below the critical micelle concentration (CMC) increased with increasing concentrations of 2, up to a mole ratio of 0.5 for 2 to 1, after which the hydrolysis rate was independent of the concentration of 2. These results suggest the possible formation of a complex between 1 and 2. A micellar solution of pure sodium dodecyl sulfate (20 mM) hydrolyzed 50 times faster than that of a premicellar solution at the same pH. Plots of log k versus pH were linear with a slope of -1 at pH less than 4.3. At a constant pH, the addition of NaCl resulted in a decrease in the rate of hydrolysis of a micellar solution. This is probably due to the reduction of concentration of protons at the micelle surface. Furthermore, kH+ was also decreased by the addition of 2 in the region where 2 is solubilized in the micelle; again, this was probably due to the reduction of the charge density (sigma) on the surface of the micelle.

Sodium deoxycholate promotes the absorption of heparin administered orally, probably by acting on gastrointestinal mucosa, in rats

Sodium deoxycholate (DOC), selected as a promoter of gastrointestinal absorption of heparin, was administered orally to rats, followed, at increasing intervals, by heparin. Maximal plasma clearing activity (PC) was obtained with a 60-min interval, though PC was still elicited after 24 h, suggesting that DOC acts on the gastrointestinal mucosa. Inhibition of blood coagulation was also observed after oral heparin. The suggestion that DOC increases heparin absorption is supported by increased plasma levels of heparin. No signs of several gastrointestinal damage were seen.

Effect of docusate sodium on drug release from a controlled-release dosage form

This study was designed to determine the effect of a clinically used surfactant, docusate sodium, on the release of chlorpheniramine from a controlled-release dosage form (encapsulated coated pellets). In vivo treatments consisted of the controlled-release capsule alone or with 200 mg of docusate sodium. Plasma chlorpheniramine levels were determined, and the AUC was calculated. No significant difference in AUC values was observed between the two treatments. At a concentration below the CMC, docusate sodium enhanced the in vitro drug release rate. The surfactant exerted a greater effect on the release of the first one-third of the drug contained in nonwax-coated pellets. At the CMC, 0.02% (w/v), docusate sodium rapidly entrapped chlorpheniramine in micelles. The overall enhanced dissolution rate in vivo may have been offset by micellar drug entrapment.

Enhancement of the intestinal absorption of ergot peptide alkaloids in the rat by micellar solutions of polyoxyethylene-24-cholesteryl ether

The incomplete intestinal absorption of hydrogenated ergot peptide alkaloids as measured in bile duct cannulated rats is much increased when the ergot compounds are administered as micellar solutions together with POE-24-cholesteryl ether. In vitro diffusion experiments with isolated intestinal mucus show that the ergot peptide alkaloids are strongly retained by the mucus layer. It is suggested that the diffusion of the ergot compounds across the mucus barrier is facilitated by micellar entrapment of the drug.

Increase of the intestinal absorption of gentamicin and amikacin by a nonionic surfactant

This study was concerned with the effect of Cetomacrogol (polyethylene glycol 1000 monocetyl ether), a nonionic surfactant, on the absorption of gentamicin and amikacin from the gastrointestinal tract of rats. A 200-mg dose of Cetomacrogol coadministered orally with 10 mg of gentamicin resulted in a mean peak gentamicin blood concentration of 14.1 microgram/ml, compared with 67.8 microgram/mg when the same gentamicin dose was administered intramuscularly. The area under the curve after administration of the oral mixture was 23% of that after the intramuscular dose. The rectal administration of the mixture resulted in a mean peak gentamicin blood level of 8.2 micrograms/ml, compares to 16.5 microgram/ml when the mixture was administered orally. A 50-mg dose of amikacin coadministered orally with 200 mg of Cetomacrogol resulted in a mean peak amikacin blood level of 13.3 microgram/ml, compared to 310 microgram/ml when this amikacin dose was administered intramuscularly. Cetomacrogol augments the intestinal absorption of gentamicin and amikacin in rats. If the toxicity of the combination in humans is limited, the combination may be potentially clinically useful.

Effective intestinal absorption of insulin in diabetic rats using a new formulation approach

Insulin injected intra-jejunally together with the non-ionic surfactant cetomacrogol was effective in streptozocin-induced diabetes in the rat, as measured by the hypoglycaemic effect. The reduction in blood sugar was maximal at about 2 h after administration but continued at a high level for the 4 h of the experiment. No hypoglycaemic effect was observed in controls injected with insulin or saline alone. Intestinal absorption of insulin has thus been effected by the addition of cetomacrogol, which appears to enhance membrane-permeability to insulin rather than to function as a protective agent preventing insulin degradation, as in liposome-encapsulation. In support of this, a significant hypoglycaemic action was still obtained when the insulin injection was given half-hour after that of the cetomacrogol, both intra-jejunally. Furthermore, oral administration of the surfactant followed by intra-jejunal injection of the insulin also gave a hypoglycaemic effect. The use of this agent to enhance insulin absorption offers the possibility of a new approach to oral insulin therapy.

Effect of surfactants on absorption through membranes IV: effects of dioctyl sodium sulfosuccinate on absorption of a poorly absorbable drug, phenolsulfonphthalein, in humans

To explore the effect of dioctyl sodium sulfosuccinate on drug absorption in humans, the urinary excretion of a poorly absorbable drug, phenolsulfonphthalein, administered in solution with and without the surfactant was determined. Coadministration of a therapeutic dose of the surfactant with the drug solution resulted in a significant increase in the initial rate of absorption. A small increase in the extent of absorption was also observed. Pretreatment with the surfactant for 6 nights, followed by administration of the drug on the 7th day, did not significantly change the rate of extent of absorption. The surfactant is thought to have a direct effect on the GI membrane, resulting in a temporary change in its permeability. This effect appears to be reversible after a few hours.