Characterization and evaluation of solid self-microemulsifying drug delivery systems with porous carriers as systems for improved carbamazepine release

A Comprehensive Guide to the Development, Evaluation, and Future Prospects of Self-nanoemulsifying Drug Delivery Systems for Poorly Water-soluble Drugs

Self-nano Emulsifying Drug Delivery Systems (SNEDDS) are novel formulations that can enhance the solubility and bioavailability of poorly water-soluble drugs. SNEDDS are composed of lipids, surfactants, co-solvents, and drugs and can spontaneously form nanoemulsions when mixed with water under mild agitation. SNEDDS can be formulated as liquid or solid dosage forms and can improve drug absorption by increasing the interfacial area, protecting the drug from degradation, and facilitating lymphatic transport. SNEDDS is characterized by various parameters such as particle size, zeta potential, droplet morphology, emulsification efficiency, drug solubility, and stability. SNEDDS offers several advantages over conventional dosage forms, such as dose reduction, faster onset of action, reduced variability, versatility, and ease of formulation. However, SNEDDS also face some limitations and challenges, such as drug precipitation, cost-effectiveness, compatibility with capsule shells, and lack of predictive in vitro models. SNEDDS has a promising future in the field of pharmaceuticals, especially for personalized medicine and targeted drug delivery.

Functionalized calcium carbonate (FCC) as a novel carrier to solidify supersaturated self-nanoemulsifying drug delivery systems (super-SNEDDS)

Functionalized calcium carbonate (FCC), a novel pharmaceutical excipient, has shown promising properties in the field of oral drug delivery. The current study aimed at evaluating the feasibility of FCC as a carrier for the solidification of self-nanoemulsifying drug delivery systems (SNEDDS) containing the poorly water-soluble model drug carvedilol (CRV). Conventional, subsaturated SNEDDS (80 %-SNEDDSliquid) and supersaturated SNEDDS (200 %-SNEDDSliquid) were loaded onto FCC via physical adsorption at three ratios; 2.5:1, 3.0:1 and 3.5:1 (w/w) of FCC:SNEDDSliquid, respectively, generating free-flowing powders (SNEDDSFCC) with drug loading ranging from 0.8 % to 2.6 % (w/w) CRV. The emulsification of SNEDDSFCC in a USP II dissolution setup (in purified water) was characterized using dynamic light scattering, resulting in similar droplet sizes and PDIs as observed for their liquid counterparts. The morphology and physical state of the obtained SNEDDSFCC were characterized using scanning electron microscopy and differential scanning calorimetry. The physical stability and drug release upon dispersion were assessed as a function of storage time. The 200 %-SNEDDSliquid were physically stable for 6 days, however, solidification using FCC stabilized the supersaturated concentrations of CRV for a test period of up to 10 weeks (solidification ratios 3.0:1 and 3.5:1 (FCC:SNEDDSliquid)). SNEDDSFCC achieved an improved rate and extent of drug release upon dispersion compared to the crystalline CRV in tap water (pH 7.5), however, to a lesser extent than their liquid counterparts. After 8 weeks of storage (25 °C at dry conditions), FCC was still able to rapidly release the SNEDDSliquid and demonstrated the same rate and extent of drug release as freshly prepared samples. The solidification of 200 %-SNEDDSliquid in presence of FCC greatly improved the drug loading and showed an enhanced drug release profile compared to the conventional systems. In conclusion, FCC showed potential as a carrier for solidification of SNEDDS and for the development of novel supersaturated solid SNEDDS for the oral delivery of poorly water-soluble drugs.

Improvement and characterization of oral absorption behavior of clofazimine by SNEDDS: Quantitative evaluation of extensive lymphatic transport

Clofazimine, an anti-leprosy drug, has been anticipated for a candidate to treat tuberculosis, cryptosporidiosis, and coronavirus infection, but its low oral bioavailability is considered a reason for its limited activity. In the current study, we have tried to improve the oral bioavailability of clofazimine by several SNEDDS formulations and characterized the absorption behavior from various aspects. Among four SNEDDS formulations prepared, SNEDDS A, prepared with castor oil as an oil component, provided the highest bioavailability (around 61%) and SNEDDS D, prepared with Capryol 90, gave the second highest bioavailability. SNEDDS A formed the finest nanoparticles, which were maintained under gastric and intestinal luminal conditions. The comparison in oral bioavailability between the SNEDDS formulation and its corresponding preformed nanoemulsion suggested that SNEDDS A would efficiently form nanoemulsion in the gastrointestinal tract after oral administration. AUC of mesenteric lymph node concentration was the highest for SNEDDS A, which would be one of the reasons for SNEDDS A to reveal the highest oral bioavailability. A cycloheximide-treated oral absorption study and single-pass perfusion study by utilizing a vascular-luminal perfused small intestine-liver preparation clearly indicated that over 90% of clofazimine absorbed to systemic circulation should be derived from lymphatic transport for both SNEDDS A and D. Furthermore, the fraction of dose absorbed was around 65% for SNEDDS D, but SNEDDS A achieved around 94%, indicating the excellent performance of SNEDDS A.

Development and Characterization of Celecoxib Solid Self-nanoemulsifying Drug Delivery Systems (S-SNEDDS) Prepared Using Novel Cellulose-Based Microparticles as Adsorptive Carriers

Self-nanoemulsifying drug delivery systems (SNEDDS) represent an interesting platform for improving the oral bioavailability of poorly soluble lipophilic drugs. While Liquid-SNEDDS (L-SNEDDS) effectively solubilize the drug in vivo, they have several drawbacks, including poor storage stability. Solid-SNEDDS (S-SNEDDS) combine the advantages of L-SNEDDS with those of solid dosage forms, particularly stability. The aim of the present study was to convert celecoxib L-SNEDDS into S-SNEDDS without altering their release behavior. Various commercially available adsorptive carrier materials were investigated, as well as novel cellulose-based microparticles prepared by spray drying from an aqueous dispersion containing Diacel^® 10 and methyl cellulose or gum arabic as a binder prior to their use. Particle size and morphology of the carrier materials were screened by scanning electron microscopy and their effects on the loading capacity for L-SNEDDS were investigated, and comparative in vitro dissolution studies of celecoxib L-SNEDDS and the different S-SNEDDS were performed immediately after preparation and after 3 months of storage. Among the adsorptive carrier materials, the novel cellulose-based microparticles were found to be the most suitable for the preparation of celecoxib S-SNEDDS from L-SNEDDS, enabling the preparation of a solid, stable formulation while preserving the in vitro release performance of the L-SNEDDS formulation.

Fabrication and Characterization of Buccal Film Loaded Self-emulsifying Drug Delivery System containing Lysiphyllum strychnifolium Stem Extracts

Lysiphyllum strychnifolium has long been used as a popular herbal medicinal plant for treating fever and alcohol intoxication. This study aimed to prepare buccal film for L. strychnifolium stem extracts. These extracts were less soluble in water and were therefore loaded in self-emulsifying systems before being mixed into the film. Astilbin was selected as a chemical marker in L. strychnifolium stem extracts. Firstly, the L. strychnifolium stem extracts were entrapped in the self-emulsifying systems which were designed and optimized based on 3² factorial design. The optimal formulation was 0.60 g of surfactant-co-surfactant mixture (Tween^® 80 and polyethylene glycol 400 in the ratio of 7.5:1) and 0.40 g of caprylic/capric triglyceride. Secondly, the optimal self-emulsifying system was loaded in the polymeric film which consisted of polyvinyl alcohol blended with poloxamer 407 using glycerin as a plasticizer. The properties of the prepared buccal film were unchanged, and the film showed an amorphous state, indicating all ingredients might be completely dissolved in the film. The buccal film could be placed in direct contact with the mouth without oral mucosal irritation, and showed a smooth and homogeneous surface with a rough and compact cross-sectional morphology. Astilbin content in the buccal film was 61.39 ± 11.45 µg/cm². Astilbin was released from the buccal film while the permeation rate was low. The release mechanism was both swelling and diffusion, and followed anomalous or non-Fickian transfer. The permeability coefficient of the cumulative amount of astilbin permeated from buccal film was 1.0192 ± 0.1395 ×10^-3 cm/h. Thus, the buccal film can be prepared by using a self-emulsifying system for herbal applications and shows potential as a safe and convenient form of oral drug administration.

Self-nanoemulsifying composition containing curcumin, quercetin, Ganoderma lucidum extract powder and probiotics for effective treatment of type 2 diabetes mellitus in streptozotocin induced rats

Liquid self-nanoemulsifying drug delivery system (L-SNEDDS) of curcumin and quercetin were prepared by dissolving them in isotropic mixture of Labrafil M1944CS®, Capmul MCM®, Tween-80® and Transcutol P®. The prepared L-SNEDDS were solidified using Ganoderma lucidum extract, probiotics and Aerosil-200® using spray drying. These were further converted into pellets using extrusion-spheronization. The mean droplet size and zeta potential of L-SNEDDS were found to be 63.46 ± 2.12 nm and - 14.8 ± 3.11 mV while for solid SNEDDS pellets, these were 72.46 ± 2.16 nm and -38.7 ± 1.34 mV, respectively. The dissolution rate for curcumin and quercetin each was enhanced by 4.5 folds while permeability was enhanced by 5.28 folds (curcumin) and 3.35 folds (quercetin) when loaded into SNEDDS pellets. The Cmax for curcumin and quercetin containing SNEDDS pellets was found 532.34 ± 5.64 ng/mL and 4280 ± 65.67 ng/mL, respectively. This was 17.55 and 3.48 folds higher as compared to their naïve forms. About 50.23- and 5.57-folds increase in bioavailability was observed for curcumin and quercetin respectively, upon loading into SNEDDS pellets. SNEDDS pellets were found stable at accelerated storage conditions. The developed formulation was able to normalize the levels of blood glucose, lipids, antioxidant biomarkers, and tissue architecture of pancreas and liver in streptozotocin induced diabetic rats as compared to their naïve forms.

Development of mushroom polysaccharide and probiotics based solid self-nanoemulsifying drug delivery system loaded with curcumin and quercetin to improve their dissolution rate and permeability: State of the art

The role of mushroom polysaccharides and probiotics as pharmaceutical excipients for development of nanocarriers has never been explored. In the present study an attempt has been made to explore Ganoderma lucidum extract powder (GLEP) containing polysaccharides and probiotics to convert liquid self nanoemulsifying drug delivery system (SNEDDS) into solid free flowing powder. Two lipophilic drugs, curcumin and quercetin were used in this study due to their dissolution rate limited oral bioavailability and poor permeability. These were loaded into liquid SNEDDS by dissolving them into isotropic mixture of Labrafill M1944CS, Capmul MCM, Tween-80 and Transcutol P. The liquid SNEDDS were solidified using probiotics and mushroom polysaccharides as carriers and Aerosil-200 as coating agent. The solidification was carried out using spray drying process. The process and formulation variables for spray drying process of liquid SNEDDS were optimized using Box Behnken Design to attain required powder properties. The release of both drugs from the optimized spray dried (SD) formulation was found to be more than 90%, whereas, it was less than 20% for unprocessed drugs. The results of DSC, PXRD and SEM, showed that the developed L-SNEDDS preconcentrate was successfully loaded onto the porous surface of probiotics, mushroom polysaccharides and Aerosil-200.

Evaluation of solid carvedilol-loaded SMEDDS produced by the spray drying method and a study of related substances

In this study, various formulations of solidified carvedilol-loaded SMEDDS with high SMEDDS loading (up to 67% w/w) were produced with the spray drying process using various porous silica-based carriers. The process yield was improved with higher atomization gas flow rate during the spray drying process and with prolonged mixing time of dispersion of liquid SMEDDS and solid porous carriers prior to the spray drying process. Depending on the choice of the carrier and the SMEDDS:carrier ratio in solid SMEDDS, different drug loading, self-microemulsifying properties, drug release rates, and released drug fractions were obtained. The products exhibited fast drug release due to preserved self-microemulsifying properties and the absence of crystalline carvedilol, which was confirmed with XRD and Raman mapping. A decrease in drug content during the stability study was observed and investigated. This was at least partially attributed to the chemical degradation of the drug. Key degradation products determined by the LC-MS method were amides formed by in situ reaction of carvedilol with fatty acids present in the oily phase of SMEDDS.

Orally administered self-emulsifying drug delivery system in disease management: advancement and patents

Introduction: Oral administration of a drug is the most common, ideal and preferred route of administration. The main problem of oral drug formulations is their low bioavailability arises from poor aqueous solubility of drug. Aqueous solubility of lipophilic drugs can be improved by various techniques like salt formation, complexation, addition of co-solvent etc. but self-emulsifying drug-delivery system (SEDDS) is getting more attention for increasing the solubility of such drugs. The SEDDS is an isotropic mixture of drug, lipids, and emulsifiers, usually with one or more hydrophilic co-solvents/co-emulsifiers. This system is having ability to generate oil-in-water (o/w) emulsions or microemulsions upon gentle agitation followed by dilution with aqueous phase. The SEDDSs are relatively newer, lipid-based technological innovations possessing unparalleled potential in improving oral bioavailability of poorly water-soluble drugs.Areas covered: This review provides updated information regarding the types of SEDDS, their preparation techniques, drug delivery and related recent patents along with marketed formulations.Expert opinion: The SEDDS has been explored for improving bioavailability, rising intra-subject heterogeneity, and increasing solubility. SEDDS offers the benefit of a protective effect against the hostile environment in the gut. The unique fabrication techniques provide specific strategy to overcome the low bioavailability and poor solubility problems.

Amelioration of lipophilic compounds in regards to bioavailability as self-emulsifying drug delivery system (SEDDS)

Background

High lipophilicity and poor aqueous solubility are the endemic problems of new drug molecules. Sixty to seventy percent of these drugs are unable to solubilize completely in aqueous media, or have very low permeability. This hampers their oral absorption and further leads to their poor bioavailability. Various researches are in progress to overcome these limitations. Novel technologies like nano-carrier systems have become popular for improving the solubility of drugs.

Main body

Lipid-based formulations, among nano systems, are taking pace for the enhancement of solubility, oral absorption, and hence the bioavailability of drugs. Among the lipid formulations, self-emulsification systems are gaining popularity by offering various advantages to delivery systems. Self-emulsifying drug delivery systems (SEDDS) are isotropic blends of oil and surfactant/co-surfactants. These ingredients upon gentle agitation in aqueous media results in the formation of o/w emulsion. In spite of many works published in SEDDS, the major concerns of this article are to discuss the various approaches to formulate a good lipid-based carrier system for poorly aqueous soluble drugs, role of various polymers, and their categories used in the formulation along-with the modern technologies used for enhancing the stability of liquid SEDDS. This review majorly focuses upon the problems related to the poor aqueous solubility of the newer lipid molecules and the solutions to overcome their solubility and in addition bioavailability.

Conclusion

As per the researches done in formulation and optimization of SEDDS for the enhancement of bioavailability of lipophilic molecules, it can be stated that the aqueous solubility as well as bioavailability can be increased by many folds compared to their marketed or other oral formulations.

Novel self-nanoemulsifying drug-delivery system enhances antileukemic properties of all-trans retinoic acid

Aim: All- trans retinoic acid (ATRA) shows erratic oral bioavailability when administered orally against leukemia, which can be solved through its incorporation in self-nanoemulsifying drug-delivery systems (SEDDS). The SEDDS developed contained a hydrophobic ion pair between benzathine (BZT) and ATRA and was enriched with tocotrienols by the input of a palm oil tocotrienol rich fraction (TRF) in its composition. Results: SEDDS-TRF-ATRA-BZT allowed the formation of emulsions with nanometric size that retained ATRA within their core after dispersion. Pharmacokinetic parameters after oral administration of SEDDS-TRF-ATRA-BZT in mice were improved compared with what was seen for an ATRA solution. Moreover, SEDDS-TRF-ATRA-BZT had improved activity against HL-60 cells compared with SEDDS without TRF. Conclusion: SEDDS-TRF-ATRA-BZT is a promising therapeutic choice over ATRA conventional medicine.

Solidification of SMEDDS by fluid bed granulation and manufacturing of fast drug release tablets

Solidification of self-microemulsifying drug delivery systems (SMEDDS) is a rising experimental field with important potential for pharmaceutical industry, however fluid-bed granulation with SMEDDS is yet an unexplored solidification technique. The aim of the study was to solidify carvedilol-loaded SMEDDS utilizing fluid bed granulation process and to investigate how the formulation variables (type of solid carrier, optimization of granulation dispersion) and fluid-bed granulation process variables can be optimized in order to achieve suitable agglomeration process, high drug loading and appropriate product characteristics. Obtained granulates exhibited complete drug release, comparable to liquid SMEDDS and superior to crystalline carvedilol, nevertheless compromise between large SMEDDS loading and appropriate flow properties of the granules has to be made. Representative granulates with highest drug loading were further compressed into tablets. It was shown that the optimal excipient selection of compression mixture and compression force can lead to fast carvedilol release even from the tablets. Selfmicroemulsifying properties were not impaired neither after the solidification process and nor after the compression of solid SMEDDS into tablets. This suggests that fluid-bed granulation with SMEDDS offers a perspective alternative for solidification of the SMEDDS, enabling preservation of self-microemulsifying properties, acceptable drug loading and complete drug release.

Nanoemulsions Loaded with Amphotericin B: Development, Characterization and Leishmanicidal Activity

Leishmaniasis is one of the most neglected diseases in the world. Its most severe clinical form, called visceral, if left untreated, can be fatal. Conventional therapy is based on the use of pentavalent antimonials and includes amphotericin B (AmB) as a second-choice drug. The micellar formulation of AmB, although effective, is associated with acute and chronic toxicity. Commercially-available lipid formulations emerged to overcome such drawbacks, but their high cost limits their widespread use. Drug delivery systems such as nanoemulsions (NE) have proven ability to solubilize hydrophobic compounds, improve absorption and bioavailability, increase efficacy and reduce toxicity of encapsulated drugs. NE become even more attractive because they are inexpensive and easy to prepare. The aim of this work was to incorporate AmB in NE prepared by sonicating a mixture of surfactants, Kolliphor® HS15 (KHS15) and Brij® 52, and an oil, isopropyl myristate. NE exhibited neutral pH, conductivity values consistent with oil in water systems, spherical structures with negative Zeta potential value, monomodal size distribution and average diameter of drug-containing droplets ranging from 33 to 132 nm. AmB did not modify the thermal behavior of the system, likely due to its dispersion in the internal phase. Statistically similar antileishmanial activity of AmB-loaded NE to that of AmB micellar formulation suggests further exploring them in terms of toxicity and effectiveness against amastigotes, with the aim of offering an alternative to treat visceral leishmaniasis.

Development of solid self-emulsifying drug delivery systems (SEDDS) to improve the solubility of resveratrol

Aim: A solid self-emulsifying drug delivery systems was developed by using the spray-drying technique, to improve the solubility of resveratrol (RES). Materials & methods: Cod liver oil and three surfactant system were tested: soy phosphatidylcholine (SPC)/Eumulgin® HRE-40 (EU)/Sodium oleate (system A); SPC/Tween®80 (TW) /Sodium oleate (system B) and SPC/EU/TW (system C). Results: The greatest incorporation was obtained with system C (21.26 mg/ml). Solid self-emulsifying drug delivery systems with the highest yield were obtained with colloidal silicon dioxide (CSD) (80.12%), and CSD sodium croscarmelose 9:1 and 5:5. RES dissolution attained 100% at 45 min with CSD:CS 5:5. Discussion: The surface modification to hydrophilic by CSD:sodium croscarmellose reduced the cohesive force among drug particles. Conclusion: The developed systems are a good approximation for the design of strategies that could allow increasing the oral bioavailability of RES.

Comparison of 1-Palmitoyl-2-Linoleoyl-3-Acetyl-Rac-Glycerol-Loaded Self-Emulsifying Granule and Solid Self-Nanoemulsifying Drug Delivery System: Powder Property, Dissolution and Oral Bioavailability

The main objective of this study was to compare the powder property, dissolution and bioavailability of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG)-loaded self-emulsifying granule system (SEGS) and solid self-nanoemulsifying drug delivery system (SNEDDS). Various SEGS formulations were prepared, and the effect of surfactant and binder on the drug solubility in them, leading to selecting sodium lauryl sulphate (SLS) and hydroxyl propyl methyl cellulose (HPMC). The SEGS and SNEDDS were prepared with PLAG/SLS/HPMC/calcium silicate/microcrystalline cellulose at the weight ratio of 1:0.25:0.1:0.5:3 employing the fluid bed granulation and spray-drying technique, respectively. Their powder properties were compared in terms of flow ability, emulsion droplet size, scanning electron microscopy, and powder X-ray diffraction. Furthermore, the solubility, dissolution, and oral bioavailability in rats of the SEGS were assessed in comparison with the SNEDDS. The SEGS and SNEDDS enhanced the solubility of the drug approximately 36- and 32-fold as compared with the drug alone; but they had no differences. The crystalline drug may exist in both the calcium silicate and microcrystalline cellulose (MCC) in the SEGS, but only in the calcium silicate in the SNEDDS. The SEGS had considerably improved the flow ability (Hausner ratio, 1.23 vs. 1.07; Carr index, 19.8 vs. 43.5%) and drug dissolution as compared with the SNEDDS. The SEGS and SNEDDS with double peak profiles, unlike the single peak of drug alone, showed a significantly higher plasma concentration and area under the curve (AUC), as compared with drug alone. Although they were not significantly different, the SEGS gave higher AUC than did the SNEDDS, suggesting its enhanced oral bioavailability of PLAG. Thus, the SEGS could be used as a powerful oral dosage form to improve the flow ability and oral bioavailability of PLAG, an oily drug.

Bioavailability Enhancement of Poorly Soluble Drugs: The Holy Grail in Pharma Industry

Background:

Bioavailability, one of the prime pharmacokinetic properties of a drug, is defined as the fraction of an administered dose of unchanged drug that reaches the systemic circulation and is used to describe the systemic availability of a drug. Bioavailability assessment is imperative in order to demonstrate whether the drug attains the desirable systemic exposure for effective therapy. In recent years, bioavailability has become the subject of importance in drug discovery and development studies.

Methods:

A systematic literature review in the field of bioavailability and the approaches towards its enhancement have been comprehensively done, purely focusing upon recent papers. The data mining was performed using databases like PubMed, Science Direct and general Google searches and the collected data was exhaustively studied and summarized in a generalized manner.

Results:

The main prospect of this review was to generate a comprehensive one-stop summary of the numerous available approaches and their pharmaceutical applications in improving the stability concerns, physicochemical and mechanical properties of the poorly water-soluble drugs which directly or indirectly augment their bioavailability.

Conclusion:

The use of novel methods, including but not limited to, nano-based formulations, bio-enhancers, solid dispersions, lipid-and polymer-based formulations which provide a wide range of applications not only increases the solubility and permeability of the poorly bioavailable drugs but also improves their stability, and targeting efficacy. Although, these methods have drastically changed the pharmaceutical industry demand for the newer potential methods with better outcomes in the field of pharmaceutical science to formulate various dosage forms with adequate systemic availability and improved patient compliance, further research is required.

Effects of Hydrophilic Carriers on Structural Transitions and In Vitro Properties of Solid Self-Microemulsifying Drug Delivery Systems

Self-microemulsifying drug delivery systems (SMEDDS) offer potential for improving the oral bioavailability of poorly water-soluble drugs. However, their susceptibilities during long term storage and in vivo precipitation issues limit their successful commercial application. To overcome these limitations, SMEDDS can be solidified with solid carriers, thus producing solid self-microemulsifying drug delivery systems (S-SMEDDS). In this study, effects of various hydrophilic carriers on structural transitions and in vitro properties of S-SMEDDS were investigated in order to set up in vitro methods for screening out appropriate carriers for S-SMEDDS. Liquid SMEDDS was prepared and characterized using nimodipine as a model drug. The effects of various hydrophilic carriers on internal microstructure and solubilization of SMEDDS were investigated by conductivity measurement and in vitro dispersion test. The results showed that hydrophilic carriers including dextran 40, maltodextrin and PVP K30 seemed to delay the percolation transition of SMEDDS, allowing it to maintain a microstructure that was more conducive to drug dissolution, thus significantly increasing the solubilization of nimodipine in the self-microemulsifying system and decreasing drug precipitation when dispersed in simulated gastric fluid. S-SMEDDS of nimodipine were prepared by using spray drying with hydrophilic carriers. The effects of various hydrophilic carriers on in vitro properties of S-SMEDDS were investigated by using SEM, DSC, PXRD and in vitro dissolution. The results showed that properties of hydrophilic carriers, especially relative molecular mass of carriers, had obvious influences on surface morphologies of S-SMEDDS, reconstitution of microemulsion and physical state of nimodipine in S-SMEDDS. Considering that in vitro properties of S-SMEDDS are closely related to their pharmacokinetic properties in vivo, the simple and economical in vitro evaluation methods established in this paper can be used to screen solid carriers of S-SMEDDS well.

Self-microemulsifying Drug Delivery System for Problematic Molecules: An Update

BACKGROUND

The poor bioavailability of a problematic molecule is predominantly due to its high lipophilicity, low solubility in gastric fluids and/or high fist pass metabolism. Self microemulsifying drug delivery system (SMEDDS), a lipidic type IV nano-formulation has been of interest in the field of pharmaceutical research due to its potential for tailoring the physicochemical properties of pharmaceutical molecules.

METHODS

This review provides insights on various recent innovations and reports from the past seven years (2012-2019) of self-emulsifying formulations for the delivery of various types of poorly soluble drugs, phytoconstituents and high molecular peptides and gives exhaustive details of the outcome of the endeavors in this field.

RESULTS

Various types of innovative formulations have been molded from SMEDDS like selfemulsifying powders, granules, tablets, pellets, eutectic and cationic formulations. Till date, many research reports and patents have been filed on self-emulsifying dosage forms and many formulations have gained US-FDA approvals which are summarized in the review article.

CONCLUSION

This review content highlighted the increasing scope of SMEDDS in augmenting the physiochemical properties of an API, the variegated formulation types and the attributes of API that can be improved by SMEDD based formulations.

Enhancement of Aqueous Solubility and Dissolution of Celecoxib through Phosphatidylcholine-Based Dispersion Systems Solidified with Adsorbent Carriers

This study aimed to design phosphatidylcholine (PC)-based solid dispersion (SD) systems for enhancing the apparent aqueous solubility and dissolution of celecoxib (CLC), a selective cyclooxygenase-2 inhibitor with a highly hydrophobic property. Although PC-based dispersion formulations considerably increased solubilities of CLC, the lipidic texture of PC was not appropriate as a solid dosage form for oral administration of CLC. To mask the lipidic texture of PC-based matrices, Neusilin^® US2, an adsorbent material with a porous structure and large surface area widely used in the pharmaceutical industry, was employed and thereby fully powderized PC-based dispersion formulations could be fabricated. However, PC matrices containing CLC strongly adsorbed to the pores of Neusilin^® US2 was not able to be rapidly released. To address this problem, different hydrophilic materials were examined to promote the release of the CLC-dispersed PC matrices from Neusilin^® US2. Among tested hydrophilic materials, croscarmellose sodium was the most suitable to facilitate fast drug dissolution from Neusilin^® US2 particles, showing significantly enhanced apparent aqueous solubility and dissolution behavior of CLC. Through differential scanning calorimetry, X-ray diffraction, and Fourier transform infrared spectroscopy (FT-IR) analysis, a considerably reduced crystallinity of CLC dispersed in the PC-based dispersion formulations was demonstrated. The PC-based SD formulations developed in this study would be useful for improving the oral bioavailability of poorly soluble drugs such as CLC.

Self-microemulsifying tablets prepared by direct compression for improved resveratrol delivery

The purpose of this study was to develop self-microemulsifying (SME-) tablets to improve resveratrol solubility whilst delivering resveratrol in a preferred tablet dosage form. Resveratrol was dissolved in liquid self-microemulsifying drug delivery system (SMEDDS) (10% w/w) and solidified through adsorption on several different solid carriers. Two ranges of synthetic amorphous silica (Sylysia® 290, 350, 470, 580; Syloid® 244FP, AL-1FP) as well as granulated magnesium aluminometasilicate (Neusilin® US2) were screened for their SMEDDS adsorbent capacity. The most efficient carrier from every range was chosen for further SME-tablet development. To counteract the high ratio of liquid in SME-tablets, additional dry binders (microcrystalline cellulose, copovidone) were added to the tableting mixture, as well as superdisintegrant (croscarmellose sodium) and lubricant (magnesium stearate). Finally, approx. 600 mg tablets were directly pressed using 12 mm flat face punch, containing 41.75% SMEDDS. Overall, all tablets exhibited sufficient hardness (>50 N), although it was negatively affected by higher compression force. Tablets with Neusilin® US2 proved to have highest hardness, as granulated structure of Neusilin® US2 provided best compaction properties needed for successful direct compression of tablets. All prepared SME tablet formulations disintegrated in under 10 min and formed microemulsions (droplet size < 100 nm) upon dilution with water, with Neusilin® US2 tablets exhibiting the lowest droplet size (<30 nm). While conventional dissolution test indicated incomplete resveratrol release from solid carriers in both pH 1.2 and 6.8 media, no difference fatty acid amount titrated during fasted state in vitro lipolysis between liquid and solid SMEDDS was observed. Moreover, accelerated stability tests confirmed over 90% of trans-resveratrol remained in solid SMEDDS following 90 days at 40 °C, with no crystallization of resveratrol observed during that time. To sum up, through adsorption on solid carriers, in particular Neusilin® US2, SMEDDS was successfully transformed into a directly compressible mixture and tableted without the loss of its self-microemulsifying ability.

Controlled Release of the Nimodipine-Loaded Self-Microemulsion Osmotic Pump Capsules: Development and Characterization

The present study was intended to develop a controlled released osmotic pump capsule based on Nimodipine (NM)-loaded self-microemulsifying drug delivery systems (SMEDDSs) in order to improve the low oral bioavailability of NM. To optimize the NM-loaded SMEDDS composition, the experiments of NM solubility in different oils, the pseudo-ternary phase diagram experiments and the different drug loading experiments were conducted in the preliminary screening studies. Controlled release of NM required an osmotic pump capsule comprising a coated semi-permeable capsule shell, plasticizer, and pore-forming agent. NM release follows zero-order kinetics after oral administration. Polyethylene glycol content, used as a pore-forming agent, coating mass, and drug release orifice size were key factors affecting drug release behavior according to the single methods and were optimized through response surface methodology. The NM-loaded SMEDDS droplet size and the ¹H NMR mass spectrogram of the novel capsule were determined. The droplet size of the reconstituted microemulsion was 39.9 nm and ¹H NMR analysis showed NM dissolution in the microemulsion. The dissolution test performed on three batches of NM-SMEDDS capsules-prepared using optimal preparation methods-indicated the capsule to deliver a qualified drug delivery with a zero-order release rate. The results demonstrated that NM-loaded SMEDDSs were successfully developed and displayed a qualified release rate in vitro.

Development of ternary solid dispersions with hydrophilic polymer and surface adsorbent for improving dissolution rate of carbamazepine

In this study solid dispersions of carbamazepine in the hydrophilic Kollidon® VA64 polymer, adsorbed onto Neusilin® UFL2 adsorption carrier have been employed to improve carbamazepine dissolution rate. In order to evaluate effects of changing in the proportions of all solid dispersion components on carbamazepine dissolution rate, D-optimal mixture experimental design was used in the formulation development. From all prepared solid dispersion formulations, significantly faster carbamazepine dissolution was observed compared to pure drug. Ternary solid dispersions containing carbamazepine, Kollidon® VA64 and Neusilin® UFL2 showed superior dissolution performances over binary ones, containing only carbamazepine and Neusilin® UFL2. Proportion of Kollidon® VA64 showed the most profound effect on the amount of carbamazepine dissolved after 10 and 30 min, whereby these parameters increase upon increasing in Kollidon® VA64 concentrations up to the middle values in the studied range of Kollidon® VA64 concentrations. Physicochemical characterization of the selected samples using differential scanning calorimetry, FT-IR spectroscopy, powder X-ray diffraction and polarizing light microscopy showed polymorphic transition of carbamazepine from more thermodynamically stable monoclinic form (form III) to less thermodynamically stable triclinic form (form I) in the case of ternary, but not of binary solid dispersion formulations. This polymorphic transition can be one of the factors responsible for improving of carbamazepine dissolution rate from studied solid dispersions. Ternary solid dispersions prepared with Kollidon® VA64 hydrophilic polymer and Neusilin® UFL2 adsorption carrier resulted in significantly improvement of carbamazepine dissolution rate, but formation of metastable polymorphic form of carbamazepine requires particular care to be taken in ensuring product long term stability.

Self-Emulsifying Granules and Pellets: Composition and Formation Mechanisms for Instant or Controlled Release

Many articles have been published in the last two decades demonstrating improvement in the dissolution and absorption of low solubility drugs when formulated into self-emulsifying drug delivery systems (SEDDS). Several such pharmaceutical products have appeared in the market for medium dose (Neoral^® for Cyclsoprin A, Kaletra^® for Lopinavir and Ritonavir), or low dose medications (Rocaltrol^® for Calcitriol and Avodart^® for Dutasteride). However, these are in the form of viscous liquids or semisolid presentations, characterized by the disadvantages of high production cost, stability problems and the requirement of large quantities of surfactants. Solid SEDDS (S-SEDDS), as coarse powders, granules or pellets, besides solubility improvement, can be filled easily into capsules or processed into tablets providing a handy dosage form with instant release, which can be further developed into controlled release by mixing with suitable polymers or coating with polymeric films. In this review, the materials used for the preparation of S-SEDDS, their properties and role in the formulations are detailed. Factors affecting the physical characteristics, mechanical properties of S-SEDDS as well as their in vitro release and in vivo absorption are discussed. The mechanisms involved in the formation of instant and sustained release self-emulsifying granules or pellets are elucidated. Relationships are demonstrated between the characteristics of S-SEDDS units (size, shape, mechanical properties, re-emulsification ability, drug migration and drug release) and the properties of the submicron emulsions used as massing liquids, with the aim to further elucidate the formation mechanisms. The influence of the composition of the powdered ingredients forming the granule or pellet on the properties of S-SEDDS is also examined. Examples of formulations of S-SEDDS that have been reported in the literature in the last thirteen years (2004–2017) are presented.

Biosafety study and mechanism comparison on two types of silica with different nanostructures

Silica is frequently used in oral drug delivery; however, its biosafety, particularly concerned with its nanostructure, has not been comprehensively studied yet. Here, the in vitro and in vivo biosafety of two types of silica (A200, nano-sized or micron-sized agglomerates; S350, micro-sized particles with nanopores) were compared and the possible reasons for the differences were explored. The results indicated that both A200 and S350 could inhibit the growth of Caco-2 cells by inducing apoptosis and changing the cell cycle progression. A200 showed a stronger influence than S350 in most of the in vitro experiments. In the in vivo study in KM mice, both A200 and S350 could change the blood constituents under the tested conditions; A200 also increased the levels of inflammatory factors in plasma and the numbers of CD4+ lymphocyte subsets. No obvious organic damage was observed in either the A200-treated or S350-treated groups. The transport study showed that neither A200 nor S350 were readily transported across the intestinal epithelial barrier in vitro and in vivo, but A200 could transport across the lymphatic-associated epithelium and accumulate in the Peyer's Patches, which might explain the A200-induced immune response. The increased transport of A200 might relate to its particle size, dispersion state and specific surface area. In conclusion, these results demonstrated that A200 and S350 exhibited diverse biosafety aspects, which correlated with their different nanostructures. We believe this study will provide some scientific information about the biosafety of A200 and S350 for their applications in oral drug delivery systems.

Preparation and In Vitro/In Vivo Evaluation of Puerarin Solid Self-Microemulsifying Drug Delivery System by Spherical Crystallization Technique

The aim of this work was to establish a method for preparing stable and controllable solid self-microemulsifying drug delivery system (S-SMEDDS) by spherical crystallization technique, which was explored for promoting the dissolution, oral bioavailability, and process efficiency. Solubility test, preparation of liquid self-microemulsifying drug delivery system (L-SMEDDS), and the obtained ternary phase diagrams test have been performed to screen and optimize the composition of LSMEDDS. The optimized formulation was used to prepare puerarin solid self-microemulsifying drug delivery system (Pue-SSMEDDS) by spherical crystallization technique. Droplet size and morphological analysis of the optimal Pue-SSMEDDS were determined to evaluate the final formulation. And the Pue-SSMEDDS was also assessed by flowability study, angle of repose, Carr's index, and flow velocity. Furthermore, the vitro dissolution and pharmacokinetic profile in vivo were analyzed. The study in vitro showed the Pue-SSMEDDS could disperse in the dispersion medium within 60 s and was spherical with the particle size of 19.66 nm and zeta potential of -28.3 mV. It could keep stable at low temperature and seal condition for 3 months. In vivo pharmacokinetic experiments of rats, the mean plasma concentration of self-microemulsion group was much higher than that of conventional tablets and could play a long-lasting efficacy, while there was no significant difference between the LSMEDDS and S-SMEDDS. The results suggested the potential of S-SMEDDS could improve the oral bioavailability of poorly water-soluble drug, such as puerarin.

Development of a solidified self-microemulsifying drug delivery system (S-SMEDDS) for atorvastatin calcium with improved dissolution and bioavailability

To improve the dissolution and oral bioavailability (BA) of atorvastatin calcium (ATV), we previously introduced an optimized self-microemulsifying drug delivery system (SMEDDS) using Capmul(®) MCM (oil), Tween(®) 20 (surfactant), and tetraglycol (cosurfactant). In this study, various solid carriers were employed to develop a solidified SMEDDS (S-SMEDDS): mannitol (M) and lactose (L) as water-soluble carriers, and Sylysia(®) 350 (S) and Aerosil(®) 200 (A) as water-insoluble carriers. Maximum solidifying capacities (SCmax) of water-insoluble carriers were significantly greater than those of water-soluble carriers were. The resultant powders were free flowing with an angle of repose <40° and Carr's index 5-20%, regardless of the solid carrier types. S-SMEDDS with mannitol (S(M)-SMEDDS) or lactose (S(L)-SMEDDS) had a smaller droplet size and greater dissolution than S-SMEDDS with Sylysia(®) 350 (S(S)-SMEDDS) or Aerosil(®) 200 (S(A)-SMEDDS). Following oral administration of various formulations to rats at a dose equivalent to 25mg/kg of ATV, plasma drug levels were measured by LC-MS/MS. The relative BAs (RBAs) of SMEDDS, S(M)-SMEDDS, and S(S)-SMEDDS were 345%, 216%, and 160%, respectively, compared to that of ATV suspension. Additionally, at a reduced dose of ATV equivalent to 5mg/kg, the RBAs of S(M)-SMEDDS and S(S)-SMEDDS compared to that of SMEDDS were 101% and 65%, respectively. These results suggest that S(M)-SEMDDS offers great potential for the development of solid dosage forms with improved oral absorption of drugs with poor water solubility.

Statistical modeling, optimization and characterization of solid self-nanoemulsifying drug delivery system of lopinavir using design of experiment

OBJECTIVE

Lopinavir (LPV), an antiretroviral protease inhibitor shows poor bioavailability because of poor aqueous solubility and extensive hepatic first-pass metabolism. The aim of the present work was to investigate the potential of the solid self-nanoemulsifying drug delivery system (S-SNEDDS) in improving dissolution rate and oral bioavailability of LPV.

MATERIALS AND METHODS

Liquid SNEDDS (L-SNEDDS) of LPV were prepared using Capmul MCM C8, Cremophor RH 40 and propylene glycol and their amounts were optimized by Scheffe's mixture design. L-SNEDDS formulations were evaluated for different physicochemical and in vitro drug release parameters. S-SNEDDS were prepared by adsorbing L-SNEDDS on Neusilin US2 and characterized for solid-state properties. In vivo bioavailability of S-SNEDDS, marketed Lopinavir + Ritonavir (LPV/RTV) formulation and pure LPV was studied in Wistar rats. Stability study of S-SNEDDS was performed as per ICH guidelines.

RESULTS AND DISCUSSION

Optimized L-SNEDDS obtained by Scheffe design had drug loading 160 ± 1.15 mg, globule size 32.9 ± 1.45 nm and drug release >95% within 15 min. Solid state studies suggested the transformation of the crystalline drug to amorphous drug. The size and zeta potential of globules obtained on dilution S-SNEDDS remained similar to L-SNEEDS. In vivo bioavailability study revealed that S-SNEDDS has 2.97 and 1.54-folds higher bioavailability than pure LPV and LPV/RTV formulation, respectively. The optimized S-SNEDDS was found to be stable and had a shelf life of 2.85 years.

CONCLUSION

The significant increase in drug dissolution and bioavailability by prepared SNEDDS suggest that the developed S-SNEDDS is a useful solid platform for improving oral bioavailability of poorly soluble LPV.

Formulation optimization of aprepitant microemulsion-loaded silicated corn fiber gum particles for enhanced bioavailability

The present investigation was aimed at development of silicate corn fiber gum (SCFG) particles as superior solid carrier for the preparation of Aprepitant (APT)-loaded self-emulsifying powder (SEP) system. 2(4) D-optimal mixture design with three level process variables was employed to develop SCFG particles, utilizing flow descriptors and hydrophobicity descriptors as response variables. The results indicated that blending of CFG (51.4% w/w) and magnesium silicate (MS) (48.6% w/w) using freeze-drying technique was found to have highest desirability (0.904). The developed SEP showed highest oil desorbing capacity, low self-emulsification time and highest drug content. It was observed that SCFG-SEP (F2 formulation) showed lowest PDI (0.2445 ± 0.03) as well as smallest particle size (127 ± 5.8 nm). The droplets were uniform and maintain their integrity after reconstitution (TEM analysis). Furthermore, APT-loaded SEP showed enhanced in vitro dissolution (4 folds) and ex vivo performance (7-fold enhanced Papp) as compared to pure APT. Furthermore, in vivo pharmacokinetic study showed that significant enhancement (p > 0.05) in Cmax was evident with APT-loaded F2 (SCFG-SEP) (1.93-fold) and F4 (Aerosil 200-SEP) (1.58-fold). The data also suggested increase in absorption rate when APT incorporated into SCFG-SEP. Thus, findings pointed toward enhanced bioavailability of APT when loaded into SCFG particles. Overall, the developed SCFG particles could be considered as a better alternative to already available solid carrier(s).

Influence of Solid Drug Delivery System Formulation on Poorly Water-Soluble Drug Dissolution and Permeability

The majority of drugs have a low dissolution rate, which is a limiting step for their absorption. In this manuscript, solid dispersions (SD), solid self-microemulsifying drug delivery systems (S-SMEDDS) and solid self-nanoemulsifying drug delivery systems (S-SNEDDS) were evaluated as potential formulation strategies to increase the dissolution rate of carbamazepine. Influence of increased dissolution rate on permeability of carbamazepine was evaluated using PAMPA test. In S-SMEDDS and S-SNEDDS formulations, the ratio of liquid SMEDDS/SNEDDS and solid carrier (Neusilin^® UFL2) was varied, and carbamazepine content was constant. In SD formulations, the ratio of carbamazepine and Neusilin^® UFL2, was varied. Formulations that showed the best dissolution rate of carbamazepine (SD_1:6, SMEDDS_1:1, SNEDDS_1:6) were mutually compared, characterization of these formulations was performed by DSC, PXRD and FT-IR analyses, and a PAMPA test was done. All formulations have shown a significant increase in dissolution rate compared to pure carbamazepine and immediate-release carbamazepine tablets. Formulation S-SMEDDS_1:1 showed the fastest release rate and permeability of carbamazepine. DSC, PXRD and FT-IR analyses confirmed that in S-SMEDDS and S-SNEDDS carbamazepine remained in polymorph form III, and that it was converted to an amorphous state in SD formulations. All formulations showed increased permeability of carbamazepine, compared to pure carbamazepine.