Development and evaluation of a solid self-nanoemulsifying drug delivery system for loratadin by extrusion-spheronization

PURPOSE

Recently the liquid nanoemulsifying drug delivery systems (SNEDDS) have shown dramatic effects on improving oral bioavailability of poorly soluble drugs. The main purpose of this study was to prepare a solid form of self-nanoemulsifying drug delivery system of loratadin by extrusion-spheronization. The liquid SNEDDS are generally prepared in a soft or hard gelatin capsules which suffers from several disadvantages. Therefore incorporation of SNEDDS into solid dosage form is desirable to get together the advantages of SNEDDS and solid multiparticualte systems.

METHODS

The SNEDDS was consisted of liquid paraffin, capriole, span 20, transcutol and loratadin as a poorly soluble drug. A multilevel factorial design was used to formulation of SNEDDS pellets, liquid SNEDDS (20 and 30%) was mixed with lactose, microcrystallin cellulose (40%) and silicon dioxide (0, 5 and 10%), and Na- crosscarmelose (0, 5 and 10%). The resulting wet mass transformed into pellets by extrusion-spheronization. The pellets were dried and characterized for size (sieve analysis), shape (image analysis), mechanical strength (friability test), droplet size (laser light scattering) and drug release rate (dissolution test). Selected SNEDDS pellets were also compared with conventional loratadin pellet or tablet formulation.

RESULTS

The resulting SNE pellets exhibited uniform size and shape. Total friability of pellets did not affected by formulation variables. The in vitro release of SNE pellets was higher than the liquid SNE and powder tablets.

CONCLUSION

Our studies demonstrated that extrusion-spheronization is a viable technology to produce self-emulsifying pellets in large scale which can improve in vitro dissolution with better solubility.

Advanced drug delivery to the lymphatic system: lipid-based nanoformulations

The delivery of drugs and bioactive compounds via the lymphatic system is complex and dependent on the physiological uniqueness of the system. The lymphatic route plays an important role in transporting extracellular fluid to maintain homeostasis and in transferring immune cells to injury sites, and is able to avoid first-pass metabolism, thus acting as a bypass route for compounds with lower bioavailability, ie, those undergoing more hepatic metabolism. The lymphatic route also provides an option for the delivery of therapeutic molecules, such as drugs to treat cancer and human immunodeficiency virus, which can travel through the lymphatic system. Lymphatic imaging is useful in evaluating disease states and treatment plans for progressive diseases of the lymph system. Novel lipid-based nanoformulations, such as solid lipid nanoparticles and nanostructured lipid carriers, have unique characteristics that make them promising candidates for lymphatic delivery. These formulations are superior to colloidal carrier systems because they have controlled release properties and provide better chemical stability for drug molecules. However, multiple factors regulate the lymphatic delivery of drugs. Prior to lymphatic uptake, lipid-based nanoformulations are required to undergo interstitial hindrance that modulates drug delivery. Therefore, uptake and distribution of lipid-based nanoformulations by the lymphatic system depends on factors such as particle size, surface charge, molecular weight, and hydrophobicity. Types of lipid and concentration of the emulsifier are also important factors affecting drug delivery via the lymphatic system. All of these factors can cause changes in intermolecular interactions between the lipid nanoparticle matrix and the incorporated drug, which in turn affects uptake of drug into the lymphatic system. Two lipid-based nanoformulations, ie, solid lipid nanoparticles and nanostructured lipid carriers, have been administered via multiple routes (subcutaneous, pulmonary, and intestinal) for targeting of the lymphatic system. This paper provides a detailed review of novel lipid-based nanoformulations and their lymphatic delivery via different routes, as well as the in vivo and in vitro models used to study drug transport in the lymphatic system. Physicochemical properties that influence lymphatic delivery as well as the advantages of lipid-based nanoformulations for lymphatic delivery are also discussed.

An injectable hybrid nanoparticle-in-oil-in-water submicron emulsion for improved delivery of poorly soluble drugs

Poor drugability problems are commonly seen in a class of chemical entities with poor solubility in water and oil, and moreover, physicochemical instability of these compounds poses extra challenges in design of dosage forms. Such problems contribute a significant high failure rate in new drug development. A hybrid nanoparicle-in-oil-in-water (N/O/W) submicron emulsion was proposed for improved delivery of poorly soluble and unstable drugs (e.g., dihydroartemisinin (DHA)). DHA is known for its potent antimalarial effect and antitumor activity. However, its insolubility and instability impose big challenges for formulations, and so far, no injectable dosage forms are clinically available yet. Therefore, an injectable DHA N/O/W system was developed. Unlike other widely-explored systems (e.g., liposomes, micelles, and emulsions), in which low drug load and only short-term storage are often found, the hybrid submicron emulsion possesses three-fold higher drug-loading capacity than the conventional O/W emulsion. Of note, it can be manufactured into a freeze-drying form and can render its storage up to 6 months even in room temperature. The in vivo studies demonstrated that the PK profiles were significantly improved, and this injectable system was effective in suppressing tumor growth. The strategy provides a useful solution to effective delivery of such a class of drugs.

In situ formation of nanocrystals from a self-microemulsifying drug delivery system to enhance oral bioavailability of fenofibrate

OBJECTIVES

In situ formation of nanocrystals and dissolution profiles of fenofibrate (FFB) from a self-microemulsifying drug delivery system (SMEDDS) were characterized.

METHODS

SMEDDS formulated with Myritol and surfactant mixture (Smix) of D-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS) and either Tween 20 (A, C, E, G, M, S, N, T, O) or Tween 80 (B, D, F, H, P, U, Q, V, R) at various oil/Smix ratios (Group I: A and B of 0.42, C and D of 0.25, E and F of 0.11; Group II: G and H of 1.38, M and P of 1.11, S and U of 0.9, N and Q of 0.73, T and V of 0.58, and O and R of 0.46) and water contents (1: 9.5%, 2: 5.0%, 3: 0.0%, G-V: 4.5%). Their dissolutions were conducted at different rotation speeds. Two optimal SMEDDSs containing Tween 80(B2) or a higher oil/Smix ratio(Q) and B2(solution) were selected for pharmacokinetic study.

RESULTS

FFB particles formed within the nanosize range from Group I gradually increased with time but decreased with increasing stirring rates. However, the mean size of FFB formed by B series was as low as 200 nm, which was smaller than that of A series at three stirring rates. The release rate from both groups obviously increased with increasing stirring rate. However, incomplete release was observed for S and N in Tween 20 series, whereas a faster release rate and complete release were observed for Tween 80 series with an insignificant difference among them. Results of pharmacokinetic study demonstrated that the highest-ranked area under the curve and Cmax values were for Q(SMEDDS) and B2(solution), respectively. The relative bioavailability of Q(SMEDDS) with respect to Tricor was enhanced by about 1.14-1.22-fold.

CONCLUSION

SMEDDS, consisting of Myritol 318 and TPGS combined with Tween 80 at 4:1, was able to enhance the oral bioavailability of FFB.

Self-microemulsifying drug delivery system for improved oral bioavailability of dipyridamole: preparation and evaluation

Dipyridamole shows poor and variable bioavailability after oral administration due to pHdependent solubility, low biomembrane permeability as well as being a substrate of P-glycoprotein. In order to improve the oral absorption of dipyridamole, a self-microemulsifying drug delivery system (SMEDDS) for dipyridamole was prepared and evaluated in vitro and in vivo. The optimum formulation was 18% oleic acid, 12% Labrafac lipophile WL 1349, 42% Solutol HS 15 and 28% isopropyl alcohol. It was found that the performance of self-microemulsification with the combination of oleic acid and Labrafac lipophile WL 1349 increased compared with just one oil. The results obtained from an in vitro dissolution assay indicated that dipyridamole in SMEDDS dissolved rapidly and completely in pH 6.8 aqueous media, while the commercial drug tablet was less soluble. An oral bioavailability study in rats showed that dipyridamole in the SMEDDS formulation had a 2.06-fold increased absorption compared with the simple drug suspension. It was evident that SMEDDS may be an effective approach to improve the oral absorption for drugs having pH-dependent solubility.

Intestinal absorption and intestinal lymphatic transport of sirolimus from self-microemulsifying drug delivery systems assessed using the single-pass intestinal perfusion (SPIP) technique and a chylomicron flow blocking approach: linear correlation with oral bioavailabilities in rats

This work aims to investigate the impact of different amount of oil or surfactant included in self-microemulsifying drug delivery systems on the intestinal lymphatic transport of sirolimus using the single-pass intestinal perfusion (SPIP) technique and a chylomicron flow blocking approach. Male Sprague-Dawley rats were pretreated intraperitoneally with 3.0mg/kg cycloheximide or saline. One hour later, single-pass intestinal perfusion experiments in jejunum and ileum and in vivo bioavailability studies were carried out to calculate the effective permeability coefficient and pharmacokinetic parameters, respectively. Drug absorption from oil-free formulation was mostly via the portal blood. In contrast, for the SMEDDS formulations containing ≥25% MCT, the lymphatic transport of sirolimus was a major contributor to oral bioavailability. The formulation including more content of oil presented higher lymphatic transport of drug and further exhibited the increased oral bioavailability. Besides, distal ileum presented much more lymphatic transport of drug compared to proximal jejunum. Furthermore, even though the smaller droplet size of resultant microemulsions and more surfactant content also can positively influence the intestinal absorption of drug, their influences on the drug intestinal lymphatic transport were relatively weaker than that of more oil content. In addition, there was a high linear correlation between the AUC values and the mean of P(eff) values in jejunum and ileum.

Enhanced oral bioavailability of vinpocetine through mechanochemical salt formation: physico-chemical characterization and in vivo studies

PURPOSE

Enhancing oral bioavailability of vinpocetine by forming its amorphous citrate salt through a solvent-free mechanochemical process, in presence of micronised crospovidone and citric acid.

METHODS

The impact of formulation and process variables (amount of polymer and citric acid, and milling time) on vinpocetine solubilization kinetics from the coground was studied through an experimental design. The best performing samples were characterized by employing a multidisciplinary approach, involving Differential scanning calorimetry, X-ray diffraction, Raman imaging/spectroscopy, X-ray photoelectron spectroscopy, solid-state NMR spectroscopy, porosimetry and in vivo studies on rats to ascertain the salt formation, their solid-state characteristics and oral bioavailability in comparison to vinpocetine citrate salt (Oxopocetine(®)).

RESULTS

The analyses attested that the mechanochemical process is a viable way to produce in absence of solvents vinpocetine citrate salt in an amorphous state.

CONCLUSION

From the in vivo studies on rats the obtained salt was four times more bioavailable than its physical mixture and bioequivalent to the commercial salt produced by conventional synthetic process implying the use of solvent.

Biowaiver extension potential and IVIVC for BCS Class II drugs by formulation design: Case study for cyclosporine self-microemulsifying formulation

The objective of this work was to suggest the biowaiver potential of biopharmaceutical classification system (BCS) Class II drugs in self-microemulsifying drug delivery systems (SMEDDS) which are known to increase the solubility, dissolution and oral absorption of water-insoluble drugs. Cyclosporine was selected as a representative BCS Class II drug. New generic candidate of cyclosporine SMEDDS (test) was applied for the study with brand SMEDDS (reference I) and cyclosporine self-emulsifying drug delivery systems (SEDDS, reference II). Solubility and dissolution of cyclosporine from SMEDDS were critically enhanced, which were the similar behaviors with BCS class I drug. The test showed the identical dissolution rate and the equivalent bioavailability (0.34, 0.42 and 0.68 of p values for AUC₀(→)₂₄(h), C(max) and T(max), respectively) with the reference I. Based on the results, level A in vitro-in vivo correlation (IVIVC) was established from these two SMEDDS formulations. This study serves as a good example for speculating the biowaiver extension potential of BCS Class II drugs specifically in solubilizing formulation such as SMEDDS.

Development of a novel self-microemulsifying drug delivery system for reducing HIV protease inhibitor-induced intestinal epithelial barrier dysfunction

The development of HIV protease inhibitors (PIs) has been one of the most significant advances of the past decade in controlling HIV infection. Unfortunately, the benefits of HIV PIs are compromised by serious side effects. One of the most frequent and deleterious side effects of HIV PIs is severe gastrointestinal (GI) disorders including mucosal erosions, epithelial barrier dysfunction, and leak-flux diarrhea, which occurs in 16-62% of patients on HIV PIs. Although the underlying mechanisms behind HIV PI-associated serious adverse side effects remain to be identified, our recent studies have shown that activation of endoplasmic reticulum (ER) stress response plays a critical role in HIV PI-induced GI complications. The objective of this study was to develop a novel self-microemulsifying drug delivery system (SMEDDS) using various antioxidants as surfactants and cosurfactants to reduce the GI side effects of the most commonly used HIV PI, ritonavir. The biological activities of this SMSDDS of ritonavir were compared with that of Norvir, which is currently used in the clinic. Rat normal intestinal epithelial cells (IEC-6) and mouse Raw 264.7 macrophages were used to examine the effect of new SMEDDS of ritonavir on activation of ER stress and oxidative stress. Sprague-Dawley rats and C57/BL6 mice were used for pharmacokinetic studies and in vivo studies. The intracellular and plasma drug concentrations were determined by HPLC analysis. Activation of ER stress was detected by Western blot analysis and secreted alkaline phosphatase (SEAP) reporter assay. Reactive oxygen species (ROS) was measured using dichlorodihydrofluorescein diacetate as a probe. Cell viability was determined by Roche's cell proliferation reagent WST-1. Protein levels of inflammatory cytokines (TNF-alpha and IL-6) were determined by enzyme-linked immunosorbent assays (ELISA). The intestinal permeability was assessed by luminal enteral administration of fluorescein isothiocyanate conjugated dextran (FITC-dextran, 4 kDa). The pathologic changes in intestine were determined by histological examination. The results indicated that incorporation of antioxidants in this new SMEDDS not only significantly reduced ritonavir-induced ER stress activation, ROS production and apoptosis in intestinal epithelial cells and macrophages, but also improved the solubility, stability and bioavailability of ritonavir, and significantly reduced ritonavir-induced disruption of intestinal barrier function in vivo. In conclusion, this new SMEDDS of ritonavir has less GI side effects compared to Norvir. This new SMEDDS can be used for other HIV PIs and any insoluble antiviral drug with serious GI side effects.

Preparation and characterization of vinpocetine loaded nanostructured lipid carriers (NLC) for improved oral bioavailability

The purpose of this study is to develop an optimized nanostructured lipid carriers (NLC) formulation for vinpocetine (VIN), and to estimate the potential of NLC as oral delivery system for poorly water-soluble drug. In this work, VIN-loaded NLC (VIN-NLC) was prepared by a high pressure homogenization method. The VIN-NLC showed spherical morphology with smooth surface under transmission electron microscope (TEM) and scanning electron microscopic (SEM) analysis. The average encapsulation efficiency was 94.9+/-0.4%. The crystallization of drug in NLC was investigated by powder X-ray diffraction and differential scanning calorimetry (DSC). The drug was in an amorphous state in the NLC matrix. In the in vitro release study, VIN-NLC showed a sustained release profile of VIN and no obviously burst release was observed. The oral bioavailability study of VIN was carried out using Wistar rats. The relative bioavailability of VIN-NLC was 322% compared with VIN suspension. In conclusion, the NLC formulation remarkably improved the oral bioavailability of VIN and demonstrated a promising perspective for oral delivery of poorly water-soluble drugs.

Formulation optimization and in situ absorption in rat intestinal tract of quercetin-loaded microemulsion

A new microemulsion system has been developed to increase the solubility and oral absorption of quercetin, a poorly water-soluble drug. The formulation of quercetin-loaded microemulsion was optimized by a simplex lattice experiment design. The optimized microemulsion formulation consisted of oil (7%, w/w), surfactant (48%, w/w), and cosurfactant (45%, w/w). Under this condition, the mean droplet diameter of microemulsion was 38.9 nm and solubility of quercetin in the microemulsion was 4.138 mg/ml. The in situ absorption property of quercetin-loaded microemulsion in rat intestine was studied and the results showed there was significant difference in absorption parameters such as K(a), t(1/2) and uptake percentages between microemulsion and micelle solution containing quercetin. The study on absorption percentage in different regions of rat intestine attested that the colon had the best permeability, followed by ileum, duodenum in order. It can be concluded that microemulsion can improve the solubility and oral absorption of quercetin, a poorly water-soluble drug.

Enhanced oral bioavailability of dexibuprofen by a novel solid self-emulsifying drug delivery system (SEDDS)

The main objective of this study was to prepare a solid form of lipid-based self-emulsifying drug delivery system (SEDDS) by spray drying liquid SEDDS with an inert solid carrier Aerosil 200 to improve the oral bioavailability of poorly water-soluble drug dexibuprofen. The liquid SEDDS was a system that consisted of dexibuprofen, Labrasol, Capryol 90 and Labrafil M 1944 CS. The particle size analysis revealed no difference in the z-average particle diameter of the reconstituted emulsion between liquid and solid SEDDS. The solid SEDDS was characterized by SEM, DSC and XRD studies. In vivo results of solid SEDDS and dexibuprofen powder in rats at the dose of 10mg/kg showed that the initial plasma concentrations of drug in solid SEDDS were significantly higher than those of dexibuprofen powder (P<0.05). The solid SEDDS gave significantly higher AUC and Cmax than did dexibuprofen powder (P<0.05). In particular, the AUC of solid SEDDS was about twofold higher than that of dexibuprofen powder. Our results suggested that this solid SEDDS could be used as an effective oral solid dosage form to improve the bioavailability of poorly water-soluble drug dexibuprofen.

Enhancement of oral absorption of curcumin by self-microemulsifying drug delivery systems

Curcumin is a poorly water-soluble drug and its oral bioavailability is very low. A new self-microemulsifying drug delivery system (SMEDDS) has been successfully developed to improve the solubility and oral absorption of curcumin. Suitable compositions of SMEDDS formulation were screened via solubility studies of curcumin and compatibility tests. The formulation of curcumin-loaded SMEDDS was optimized by a simplex lattice experiment design. The optimal formulation of SMEDDS was comprised of 57.5% surfactant (emulsifier OP:Cremorphor EL = 1:1), 30.0% co-surfactant (PEG 400) and 12.5% oil (ethyl oleate). The solubility of curcumin (21 mg/g) significantly increased in SMEDDS. The average particle size of SMEDDS-containing curcumin was about 21 nm when diluted in water. No significant variations in particle size and curcumin content in SMEDDS were observed over a period of 3 months at 4 degrees C. The spherical shape of microemulsion droplet was observed under TEM. The dissolution study in vitro showed that more than 95% of curcumin in SMEDDS could be dissolved in pH 1.2 or pH 6.8 buffer solutions in 20 min, however, less than 2% for crude curcumin in 60 min.The in situ absorption property of curcumin-loaded SMEDDS was evaluated in intestines of rats. The results showed the absorption of curcumin in SMEDDS was via passive transfer by diffusion across the lipid membranes. The results of oral absorption experiment in mice showed that SMEDDS could significantly increase the oral absorption of curcumin compared with its suspension. Our study illustrated that the developed SMEDDS formulation held great potential as a possible alternative to traditional oral formulations of curcumin.