Mucus permeating self-emulsifying drug delivery systems (SEDDS): About the impact of mucolytic enzymes

Intestinal nanoparticle delivery and cellular response: a review of the bidirectional nanoparticle-cell interplay in mucosa based on physiochemical properties

Orally administered nanocarriers play an important role in improving druggability, promoting intestinal absorption, and enhancing therapeutic applications for the treatment of local and systemic diseases. However, the delivering efficiency and cell response in mucosa to orally administered nanocarriers is affected by the physiological environment and barriers in the gastrointestinal tract, the physicochemical properties of the nanocarriers, and their bidirectional interactions. Goblet cells secrete and form extracellular mucus, which hinders the movement of nanoparticles. Meanwhile, intestinal epithelial cells may absorb the NPs, allowing for their transcytosis or degradation. Conversely, nanoparticle-induced toxicity may occur as a biological response to the nanoparticle exposure. Additionally, immune response and cell functions in secretions such as mucin, peptide, and cytokines may also be altered. In this review, we discuss the bidirectional interactions between nanoparticles and cells focusing on enterocytes and goblet cells, M cells, and immune cells in the mucosa according to the essential role of intestinal epithelial cells and their crosstalk with immune cells. Furthermore, we discuss the recent advances of how the physiochemical properties of nanoparticles influence their interplay, delivery, and fate in intestinal mucosa. Understanding the fate of nanoparticles with different physiochemical properties from the perspective of their interaction with cells in mucosa provides essential support for the development, rational design, potency maximation, and application of advanced oral nanocarrier delivery systems.

Tadpole-Like Anisotropic Polymer/Lipid Janus Nanoparticles for Nose-to-Brain Drug Delivery: Importance of Geometry, Elasticity on Mucus-Penetration Ability

Asymmetric geometry (aspect ratio >1), moderate stiffness (i.e., semielasticity), large surface area, and low mucoadhesion of nanoparticles are the main features to reach the brain by penetrating across the nasal mucosa. Herein, a new application has been presented for the use of multifunctional Janus nanoparticles (JNPs) with controllable geometry and size as a nose-to-brain (N2B) delivery system by changing proportions of Precirol ATO 5 and polycaprolactone compartments and other operating conditions. To bring to light the N2B application of JNPs, the results are presented in comparison with polymer and solid lipid nanoparticles, which are frequently used in the literature regarding their biopharmaceutical aspects: mucoadhesion and permeability through the nasal mucosa. The morphology and geometry of JPs were observed via cryogenic-temperature transmission electron microscopy images, and their particle sizes were verified by dynamic light scattering, atomic force microscopy, and scanning electron microscopy. Although all NPs showed penetration across the mucus barrier, the best increase in penetration was observed with asymmetric and semielastic JNPs, which have low interaction ability with the mucus layer. This study presents a new and promising field of application for a multifunctional system suitable for N2B delivery, potentially benefiting the treatment of brain tumors and other central nervous system diseases.

Recent Advancements in the Development of Nanocarriers for Mucosal Drug Delivery Systems to Control Oral Absorption

Oral administration of active pharmaceutical ingredients is desirable because it is easy, safe, painless, and can be performed by patients, resulting in good medication adherence. The mucus layer in the gastrointestinal (GI) tract generally acts as a barrier to protect the epithelial membrane from foreign substances; however, in the absorption process after oral administration, it can also disturb effective drug absorption by trapping it in the biological sieve structured by mucin, a major component of mucus, and eliminating it by mucus turnover. Recently, functional nanocarriers (NCs) have attracted much attention due to their immense potential and effectiveness in the field of oral drug delivery. Among them, NCs with mucopenetrating and mucoadhesive properties are promising dosage options for controlling drug absorption from the GI tracts. Mucopenetrating and mucoadhesive NCs can rapidly deliver encapsulated drugs to the absorption site and/or prolong the residence time of NCs close to the absorption membrane, providing better medications than conventional approaches. The surface characteristics of NCs are important factors that determine their functionality, owing to the formation of various kinds of interactions between the particle surface and mucosal components. Thus, a deeper understanding of surface modifications on the biopharmaceutical characteristics of NCs is necessary to develop the appropriate mucosal drug delivery systems (mDDS) for the treatment of target diseases. This review summarizes the basic information and functions of the mucosal layer, highlights the recent progress in designing functional NCs for mDDS, and discusses their performance in the GI tract.

The Development of Dermal Self-Double-Emulsifying Drug Delivery Systems: Preformulation Studies as the Keys to Success

Self-emulsifying drug delivery systems (SEDDSs) are lipid-based systems that are superior to other lipid-based oral drug delivery systems in terms of providing drug protection against the gastrointestinal (GI) environment, inhibition of drug efflux as mediated by P-glycoprotein, enhanced lymphatic drug uptake, improved control over plasma concentration profiles of drugs, enhanced stability, and drug loading efficiency. Interest in dermal spontaneous emulsions has increased, given that systems have been reported to deliver drugs across mucus membranes, as well as the outermost layer of the skin into the underlying layers. The background and development of a double spontaneous emulsion incorporating four anti-tubercular drugs, clofazimine (CFZ), isoniazid (INH), pyrazinamide (PZY), and rifampicin (RIF), are described here. Our methods involved examination of oil miscibility, the construction of pseudoternary phase diagrams, the determination of self-emulsification performance and the emulsion stability index of primary emulsions (PEs), solubility, and isothermal micro calorimetry compatibility and examination of emulsions via microscopy. Overall, the potential of self-double-emulsifying drug delivery systems (SDEDDSs) as a dermal drug delivery vehicle is now demonstrated. The key to success here is the conduct of preformulation studies to enable the development of dermal SDEDDSs. To our knowledge, this work represents the first successful example of the production of SDEDDSs capable of incorporating four individual drugs.

Papain-Decorated Mucopenetrating SEDDS: A Tentative Approach to Combat Absorption Issues of Acyclovir via the Oral Route

The aim of the current study was to enhance the oral bioavailability of Acyclovir (ACV) based on the papain-functionalized self-emulsifying drug delivery systems (SEDDS). The optimum control SEDDS formulation comprised of kolliphore (40%), transcutol (30%), propylene glycol (20%) and oleoyl chloride (10%). However, in the targeted SEDDS formulation, oleoyl chloride was replaced with oleoyl chloride-papain (OC-PAP) conjugate that was synthesized via an amide bond formation between the acyl halide groups of oleoyl chloride and the amino group of papain. Prior to adding in the SEDDS formulation, the newly synthesized conjugate was evaluated quantitatively by a Bradford assay that demonstrated 45 µg of papain contents per mg of the conjugate. Moreover, the conjugate formation was qualitatively confirmed through FTIR analysis and thin layer chromatography. ACV (a BCS class III drug) was incorporated into the SEDDS formulations after being hydrophobically ion paired with sodium deoxycholate, thereby making it lipophilic. The drug-loaded formulations were emulsified in the 0.1 M phosphate buffer (pH 6.8) and evaluated in vitro with respect to drug release and rabbit mucosal permeation studies. Both the formulations illustrated a very comparable drug release over a period of 4 h, afterwards, the OC-PAP-based formulation demonstrated a more sustaining effect. The extent of mucus diffusion evaluated via the silicon tube method demonstrated a 4.92-fold and a 1.46-fold higher penetration of the drug, a 3.21-fold and a 1.56-fold higher permeation through the rabbit intestinal mucus layer, and a 22.94-fold and a 2.27-fold higher retention of the drug over the intact mucosa of rabbit intestine, illustrated by OC-PAP-based nanoemulsions compared to the drug-free solution and controlled nanoemulsion, respectively. According to these in vitro results, papain-functionalized SEDDS is a promising approach for the oral delivery of ACV and many other drugs with oral bioavailability issues, however, in vivo studies in this respect have to be employed before making a comprehensive conclusion.

Development of Self-Emulsifying Drug Delivery Systems (SEDDSs) Displaying Enhanced Permeation of the Intestinal Mucus Following Sustained Release of Prototype Thiol-Based Mucolytic Agent Load

In this study, mucoactive self-emulsifying drug delivery systems (SEDDSs) based on sustained release of N-acetylcysteine (NAC) were developed for providing effective intestinal mucopermeation. Polymeric ionic complexes of NAC were formed with polyethyleneimine (PEI), Eudragit E 100, and Eudragit RS 100 and loaded into a novel SEDDS. The SEDDSs exhibited a stable average size of 75 ± 12 nm (polydispersity index (PDI) < 0.3) and showed a rise in the zeta potential from −17.31 mV to −7.72 mV. On Caco-2 cells, SEDDSs at 1−3% were non-cytotoxic. An average of 91.8 ± 5.4% NAC was released from SEDDSs containing Eudragit E 100 (p ≤ 0.05) and Eudragit RS 100 (p ≤ 0.001) complexes at a significantly slower rate within 80 min, whereas the SEDDS containing PEI released NAC in a matter of seconds. Similarly, the SEDDS complexes revealed a time-dependent reduction in mucus dynamic viscosity of 52.6 ± 19.9%. Consequently, as compared with a blank SEDDS, mucodiffusion revealed about 2- and 1.8-fold significantly greater mucopermeation of SEDDSs anchoring Eudragit E 100−NAC and RS 100−NAC complexes (p ≤ 0.05), respectively. The mucoactive SEDDSs, which steadily released NAC while permeating the mucus, were linked to a significantly increased mucopermeation in vitro as a result of optimal mucolytic targeting.

Multi-strategic approaches for enhancing active transportation using self-emulsifying drug delivery system

Oral delivery is the most desired route of drug administration and it can be more beneficial for patients suffering from chronic diseases wherein frequent parenteral administration of proteins such as insulin and calcitonin is required. The BCS class II drugs show low aqueous solubility and high permeability whereas BCS class IV drugs suffer from low aqueous solubility and low permeability. Additionally, biologic drugs are highly sensitive to presence of bioenzymes and bile salts when administered orally. Self-emulsifying drug delivery system (SEDDS) is a thermodynamically stable lipid formulation that enhances oral absorption of active ingredients via the opening of tight junctions, increasing the membrane fluidity, and thus overcomes the physiological barriers like viscous mucus layer, strong acid conditions and enzymatic degradation. An understanding of different theories that govern SEDDS formation and drug release can help in formulating a highly stable and effective drug delivery system. Poorly permeable drugs such as chlorpromazine require modification using methods like hydrophobic ion pairing, complexation with phospholipids, etc. to enable high entrapment efficiency which is discussed in the article. Additionally, the article gives an overview of the influence of polymers, length of fatty acids chain and zeta potential in enhancing permeation across the intestinal membrane.

Dual-Acting Zeta-Potential-Changing Micelles for Optimal Mucus Diffusion and Enhanced Cellular Uptake after Oral Delivery

Context: Overcoming the intestinal mucosal barrier can be a challenge in drug delivery. Nanoemulsions with negative zeta potentials can effectively permeate the mucus layer, but those with positive zeta potentials are better taken up by cells; a nanoemulsion with capricious zeta potential from negative to positive can achieve both good permeation and high uptake. Objective: This study aimed to develop dual-acting zeta-potential-amphoteric micelles enabling optimal muco-permeation and enhancement of cellular uptake. Methods: A micellar pre-concentrate was prepared from 15% Labrasol, 15% Kolliphor EL, 30% Kolliphor RH 40, and 40% dimethylsulfoxide. The micellar pre-concentrate was loaded with anionic stearic acid (SA), forming ionic complexes with cationic polymers at a ratio of 25:1 with Eudragit RS 100 and Eudragit RL 100. Blank micelles and those containing complexes were separately diluted in physiological buffers and examined for their droplet sizes, polydispersity indices (PDIs), zeta potentials, and cytotoxicity. The SA release from the micellar complexes was evaluated in 0.1 mM phosphate buffer (pH 6.8) containing 0.001% fluorescein, thereby enabling an instant decrease in fluorescence. Finally, the micelles were loaded with the model drug fluorescein diacetate (FDA) and evaluated for their muco-permeation behavior and cellular uptake. Results: The micellar dilutions formed micelles at the critical micelle concentration (CMC) of 312 µg/mL and showed a uniform average droplet size of 14.2 nm, with a PDI < 0.1. Micellar dilutions were non-cytotoxic when used at 1:100 in a physiological medium. Micelles loaded with ionic complexes achieved a sustained release of 95.5 ± 3.7% of the SA in 180 min. Moreover, the zeta potential of the complex-loaded micelles shifted from −5.4 to +1.8 mV, whereas the blank micelles showed a stabilized zeta potential of −10 mV. Furthermore, the negatively charged blank and complex-loaded micelles exhibited comparable muco-permeation, with an overall average of 58.2 ± 3.7% diffusion of FDA. The complex-loaded micellar droplets, however, provided a significantly higher cellular uptake of the model drug FDA (2.2-fold, p ≤ 0.01) Conclusion: Due to undergoing a shift in zeta potential, the modified micelles significantly enhanced cellular uptake while preserving mucus-permeating properties.

Gastrointestinal lipolysis and trans-epithelial transport of SMEDDS via oral route

Self-microemulsifying drug delivery systems (SMEDDSs) have recently returned to the limelight of academia and industry due to their enormous potential in oral delivery of biomacromolecules. However, information on gastrointestinal lipolysis and trans-epithelial transport of SMEDDS is rare. Aggregation-caused quenching (ACQ) fluorescent probes are utilized to visualize the in vivo behaviors of SMEDDSs, because the released probes during lipolysis are quenched upon contacting water. Two SMEDDSs composed of medium chain triglyceride and different ratios of Tween-80 and PEG-400 are set as models, meanwhile Neoral® was used as a control. The SMEDDS droplets reside in the digestive tract for as long as 24 h and obey first order kinetic law of lipolysis. The increased chain length of the triglyceride decreases the lipolysis of the SMEDDSs. Ex vivo imaging of main tissues and histological examination confirm the trans-epithelial transportation of the SMEDDS droplets. Approximately 2%-4% of the given SMEDDSs are transported via the lymph route following epithelial uptake, while liver is the main termination. Caco-2 cell lines confirm the cellular uptake and trans-epithelial transport. In conclusion, a fraction of SMEDDSs can survive the lipolysis in the gastrointestinal tract, permeate across the epithelia, translocate via the lymph, and accumulate mainly in the liver.

Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery

Approximately one third of newly discovered drug molecules show insufficient water solubility and therefore low oral bio-availability. Self-nano-emulsifying drug-delivery systems (SNEDDSs) are one of the emerging strategies developed to tackle the issues associated with their oral delivery. SNEDDSs are composed of an oil phase, surfactant, and cosurfactant or cosolvent. SNEDDSs characteristics, their ability to dissolve a drug, and in vivo considerations are determinant factors in the choice of SNEDDSs excipients. A SNEDDS formulation can be optimized through phase diagram approach or statistical design of experiments. The characterization of SNEDDSs includes multiple orthogonal methods required to fully control SNEDDS manufacture, stability, and biological fate. Encapsulating a drug in SNEDDSs can lead to increased solubilization, stability in the gastro-intestinal tract, and absorption, resulting in enhanced bio-availability. The transformation of liquid SNEDDSs into solid dosage forms has been shown to increase the stability and patient compliance. Supersaturated, mucus-permeating, and targeted SNEDDSs can be developed to increase efficacy and patient compliance. Self-emulsification approach has been successful in oral drug delivery. The present review gives an insight of SNEDDSs for the oral administration of both lipophilic and hydrophilic compounds from the experimental bench to marketed products.

Formulation, Pharmacokinetic Evaluation and Cytotoxicity of an Enhanced- penetration Paclitaxel Nanosuspension

BACKGROUND

Improving poorly soluble drugs into druggability was a major problem faced by pharmaceutists. Nanosuspension can improve the druggability of insoluble drugs by improving the solubility, chemical stability and reducing the use of additives, which provided a new approach for the development and application of the insoluble drugs formulation. Paclitaxel (PTX) is a well-known BCS class IV drug with poor solubility and permeability. Also, many studies have proved that paclitaxel is a substrate of the membrane-bound drug efflux pump P-glycoprotein (P-gp), therefore it often shows limited efficacy against the resistant tumors and oral absorption or uptake.

OBJECTIVE

To manufacture an enhanced-penetration PTX nanosuspension (PTX-Nanos), and evaluate the physicochemical property, pharmacokinetics and tissue distribution in vivo and cytotoxic effect in vitro.

METHODS

PTX-Nanos were prepared by microprecipitation-high pressure homogenization, with a good biocompatibility amphiphilic block copolymer poly(L-phenylalanine)-b-poly(L-aspartic acid) (PPA-PAA) as stabilizer.

RESULTS

The PTX-Nanos had a sustained-dissolution manner and could effectively reduce plasma peak concentration and extend plasma circulating time as compared to PTX injection, markedly passively targeting the MPS-related organs, such as liver and spleen. This unique property might enhance treatment of cancer in these tissues and reduce the side effects in other normal tissues. Moreover, the hybrid stabilizers could enhance penetration of PTX in PTX-Nanos to multidrug resistance cells.

CONCLUSION

To sum up, our results showed that the optimal formula could improve the solubility of PTX and the stability of the product. The PTX-Nanos developed in this research would be a promising delivery platform in cancer treatment.

Lipid-based mucus penetrating nanoparticles and their biophysical interactions with pulmonary mucus layer

Lungs are critical organs that are continuously exposed to exogeneous matter. The presence of the mucus layer helps to protect them via its adhesive structure and filtering mechanisms. Mucus also acts as a strong barrier against the drugs and nanocarriers in drug delivery. In this study, solid lipid nanoparticles (SLNs), at different sizes and surface properties, were prepared and their spreading/penetration ability was tested for their use in pulmonary drug delivery. The biophysical interactions of SLNs have been studied via light scattering (LS) and zeta potential analyses by incubating the SLNs in mucin solution and forming a model mucus layer using a Langmuir-Blodgett (LB) trough. In addition, the penetration performance of the particles was evaluated using Franz diffusion cell and rotating diffusion tubes. It was determined that 36% of SLNs can penetrate through a 1.2 ± 0.2-mm-thick mucus layer. Finally, the spreading behavior of the particles on a mucus-mimicking subphase was characterized and enhanced using a catanionic surfactant mixture. Overall, the current study was the first to investigates both the spreading and penetration performance of SLNs. The developed systems offer a drug delivery system that is able to achieve high penetration rates through a thick mucus layer.

Mucus, mucins, and cystic fibrosis

Cystic fibrosis (CF) is both the most common and most lethal genetic disease in the Caucasian population. CF is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and is characterized by the accumulation of thick, adherent mucus plaques in multiple organs, of which the lungs, gastrointestinal tract and pancreatic ducts are the most commonly affected. A similar pathogenesis cascade is observed in all of these organs: loss of CFTR function leads to altered ion transport, consisting of decreased chloride and bicarbonate secretion via the CFTR channel and increased sodium absorption via epithelial sodium channel upregulation. Mucosa exposed to changes in ionic concentrations sustain severe pathophysiological consequences. Altered mucus biophysical properties and weakened innate defense mechanisms ensue, furthering the progression of the disease. Mucins, the high-molecular-weight glycoproteins responsible for the viscoelastic properties of the mucus, play a key role in the disease but the actual mechanism of mucus accumulation is still undetermined. Multiple hypotheses regarding the impact of CFTR malfunction on mucus have been proposed and are reviewed here. (a) Dehydration increases mucin monomer entanglement, (b) defective Ca²⁺ chelation compromises mucin expansion, (c) ionic changes alter mucin interactions, and (d) reactive oxygen species increase mucin crosslinking. Although one biochemical change may dominate, it is likely that all of these mechanisms play some role in the progression of CF disease. This article discusses recent findings on the initial cause(s) of aberrant mucus properties in CF and examines therapeutic approaches aimed at correcting mucus properties.

Formulation and characterisation of a self‐nanoemulsifying drug delivery system of amphotericin B for the treatment of leishmaniasis

This study was aimed to develop a self‐nanoemulsifying drug delivery system (SNEDDS) for amphotericin B (AmB) potential use in leishmaniasis through topical and oral routes. Two formulations, formulation A and formulation B (FA and FB) of AmB loaded SNEDDS were developed by mixing their excipients through vortex and sonication. The SNEDDS formulation FA and FB displayed a mean droplet size of 27.70 ± 0.5 and 30.17 ± 0.7 nm and zeta potential −11.4 ± 3.25 and −13.6 ± 2.75 mV, respectively. The mucus permeation study showed that formulation FA and FB diffused 1.45 and 1.37%, respectively in up to 8 mm of mucus. The cell permeation across Caco‐2 cells monolayer was 10 and 11%, respectively. Viability of Caco‐2 cells was 89% for FA and 86.9% for FB. The anti‐leishmanial activities of FA in terms of IC₅₀ were 0.017 µg/ml against promastigotes and 0.025 µg/ml against amastigotes, while IC₅₀ values of FB were 0.031 and 0.056 µg/ml, respectively. FA and FB killed macrophage harboured Leishmania parasites in a dose‐dependent manner and a concentration of 0.1 µg/ml killed 100% of the parasites. These formulations have the potential to provide a promising tool for AmB use through oral and topical routes in leishmaniasis therapy.

SEDDS: A game changing approach for the oral administration of hydrophilic macromolecular drugs

Since the development of self-emulsifying drug delivery systems (SEDDS) in 1980's, they attract the attention of researchers in order to confront the challenge of poor water-solubility of orally given drugs. Within recent years, SEDDS were also discovered for oral administration of hydrophilic macromolecular drugs such as peptides, proteins, polysaccharides and pDNA. Due to hydrophobic ion pairing (HIP) with oppositely charged lipophilic auxiliary agents the resulting complexes can be incorporated in the lipophilic phase of SEDDS. Depending on the solubility of the complex in the SEDDS pre-concentrate and in the release medium drug release can be adjusted on purpose by choosing more or less lipophilic auxiliary agents in appropriate quantities for HIP. Within the oily droplets formed in the GI-tract drugs are protected towards degradation by proteases and nucleases and thiol-disulfide exchange reactions with dietary proteins. The oily droplets can be made mucoadhesive or highly mucus permeating depending on their target site. Furthermore, even their cellular uptake properties can be tuned by adjusting their zeta potential or decorating them with cell penetrating peptides. The potential of SEDDS for oral administration of hydrophilic macromolecular drugs could meanwhile be demonstrated via various in vivo studies showing a bioavailability at least in the single digit percentage range. Owing to these properties advanced SEDDS turned out to be a game changing approach for the oral administration of hydrophilic macromolecular drugs.

Self-emulsifying drug delivery system: Mucus permeation and innovative quantification technologies

Mucus is a dynamic barrier which covers and protects the underlying mucosal epithelial membrane against bacteria and foreign particles. This protection mechanism extends to include therapeutic macromolecules and nanoparticles (NPs) through trapping of these particles. Mucus is not only a physical barrier that limiting particles movements based on their sizes but it selectively binds with particles through both hydrophilic and lipophilic interactions. Therefore, nano-carriers for mucosal delivery should be designed to eliminate entrapment by the mucus barrier. For this reason, different strategies have been approached for both solid nano-carriers and liquid core nano-carriers to synthesise muco-diffusive nano-carrier. Among these nano-strategies, Self-Emulsifying Drug Delivery System (SEDDS) was recognised as very promising nano-carrier for mucus delivery. The system was introduced to enhance the dissolution and bioavailability of orally administered insoluble drugs. SEDDS has shown high stability against intestinal enzymatic activity and more importantly, relatively rapid permeation characteristics across mucus barrier. The high diffusivity of SEDDS has been tested using various in vitro measurement techniques including both bulk and individual measurement of droplets diffusion within mucus. The selection and processing of an optimum in vitro technique is of great importance to avoid misinterpretation of the diffusivity of SEDDS through mucus barrier. In conclusion, SEDDS is a system with high capacity to diffuse through intestinal mucus even though this system has not been studied to the same extent as solid nano-carriers.

Selective permeability of mucus barriers

Mucus is a hydrogel that exhibits complex selective permeability, permitting the passage of some particles while restricting the passage of other particles including important therapeutics. In this review, we discuss biochemical mechanisms underlying mucus penetration and mucus binding, emphasizing the importance of steric, electrostatic, and hydrophobic interactions. We discuss emerging techniques for engineering nanoparticle surface chemistries for mucus penetration as well as recent advances in tuning mucus interactions with small molecule, peptide, or protein therapeutics. Finally, we highlight recent work suggesting that mucus permeability can serve as a biomarker for disease and physiological states such as pregnancy.

Enzyme decorated drug carriers: Targeted swords to cleave and overcome the mucus barrier

The use of mucus permeating drug carrier systems being able to overcome the mucus barrier can lead to a remarkable enhancement in bioavailability. One promising approach is the design of mucolytic enzyme decorated carrier systems (MECS). These systems include micro- and nanoparticles as well as self-emulsifying drug delivery systems (SEDDS) decorated with mucin cleaving enzymes such as papain (PAP) or bromelain (BRO). MECS are able to cross the mucus barrier in a comparatively efficient manner by cleaving mucus substructures in front of them on their way to the epithelium. Thereby these enzymes hydrolyze peptide bonds of mucus glycoproteins forming tiny holes or passages through the mucus. In various in vitro and in vivo studies MECS proved to be superior in their mucus permeating properties over nanocarriers without enzyme decoration. PAP decorated nanoparticles, for instance, remained 3h after oral administration to an even 2.5-fold higher extend in rat small intestine than the corresponding undecorated nanoparticles permeating the intestinal mucus gel layer to a much lower degree. As MECS break up the mucus network only locally without destroying its overall protective barrier function, even long term treatments with such systems seem feasible. Within this review article we address different drug carrier systems decorated with various types of enzymes, their particular pros and cons and potential applications.