Current Drug Delivery - Volume 13, Issue 7, 2016

To assess in vivo behavior through in vitro method, the dissolution test is mostly used, both for quality control (QC) and for development purpose. In view of the fact that a dissolution test can hardly achieve two goals at the same time, the design of dissolution testing generally varies along with the development stage of drug products and therefore the selection of dissolution media may change with the goals of the dissolution test. To serve the QC purpose, a dissolution medium is designed to provide a sink condition; for development purpose, the dissolution medium is required to simulate the physiological conditions in the gastrointestinal tract as far as possible. In this review, we intended to provide an initial introduction to the various dissolution media applied for QC and formulation development purposes for poorly water soluble drugs. We focused on these methods like addition of cosolvents, surfactants and utilization of biphasic media, applied to provide sink conditions which are difficult to be achieved by simple aqueous buffers for lipophilic drugs, and introduced the development of physiologically relevant media for human and animals like dog and rat with respect to the choice of buffers, bile salts, lipids and so on. In addition, we further discussed the influence of biorelevant dissolution media on the modification of drug Biopharmaceutical Classification System (BCS) classification, especially for BCS class II drugs with low solubility and high permeability, the solubility of which is relatively sensitive to the presence of bile salts and lipids.

Background: Gut microbiota has a significant role in the pathogenesis of diabetes. Colonic microflora modulation using an antibiotic might have an emerging role to treat the metabolic disorders. The present study was aimed to optimize the Moxifloxacin loaded chitosan microspheres (MCMs) by emulsion cross linking method for colon targeted delivery to alter the microflora. Methods: Preliminary optimization of MCMs was carried out using Placket-Burman design (PBD) following by final optimization with Box-Behnken design (BBD). Optimized MCMs were evaluated for yield, particle size, entrapment efficiency and in vitro/ in vivo antimicrobial activities. Results: FTIR spectroscopy of MCMs confirms the absence of chemical interactions during the formulation. MCMs were found to be smooth, spherical with particle size around 20μm. An enteric coating of MCMs prevented the drug release in the acidic environment of the stomach and ileum with complete release at the colon. MCMs had followed the korsmeyer - peppas model of drug release, indicating the drug release by non-fickian diffusion pattern. MCMs showed significant in vitro antimicrobial activity against Lactobacillus casei and Escherichia coli. In vivo results of MCMs exhibited prolonged antimicrobial effect of drug in the cecal content of rats. Significant protective activity observed in the ileum and colon histology in rats treated with MCMs compared to the pure drug. Conclusion: MCMs were formulated by emulsion cross linking method using QBD approach. An enteric coating around the microspheres prevented the premature drug release at upper gastrointestinal tract, while chitosan cross linking has provided the sustain release of the drug in the colonic region over the time.

Background: The management of TB is difficult due to the resistance developed by Mycobacterium tuberculosis against anti-tubercular drugs causes the new challenges for treating and managing the disease. Objective: The objective of the study was to combat multiple drug resistance (MDR) exhibited by mycobacterium species by synthesizing Dual Drug Conjugate nanoparticle (DDC) using Isoniazid (INH) and Moxifloxacin (MOXI). Method: The reaction was nucleophilic substitution using hydrolysable linkers like Chloroacetyl chloride (CAC) & Succinyl chloride (SCL). The drugs were covalently linked as INH-CAC-MOXI (DDC-1) and INH-SCL-MOXI (DDC-2). The DDC-1 & DDC-2 were subjected to hydrolysability tests at different pH solutions. The modified drugs were formulated into Poly (D, L-Lactic-co-Glycolide) nanoparticles using single emulsion technique. Design Expert® (version 8.0.1) software was used for designing, and evaluating the prepared formulation by employing response surface, optimal design of experiment technique. Result: The prepared nanoparticles were characterized for compatibility studies using Fourier Transform Infrared Spectroscopy, Nuclear Magnetic Resonance, particle size, size distribution, Zeta potential, drug entrapment efficiency and Scanning Electron Microscopy. Microbiological studies on pure drug and the conjugate indicated better activity of conjugate compared to pure drug alone or 1:1 physical mixture of drug. The nanoparticles were further subjected to drug release studies and accelerated stability studies. Conclusion: The present study offers a key to the challenge of loading different types of drugs onto the same drug delivery vehicle with efficient loading capacity, thus enabling better treatment for TB.

The aim of this study was to design a silica-supported solid dispersion of lacidipine (LCDP) to enhance the dissolution rate and oral absorption using supercritical CO2 (scCO2) as a solvent. The formulation was characterized using differential scanning calorimetry, powder X-ray diffraction, scanning electron microscopy and fourier transformed infrared spectroscopy. In the dissolution test, LCDP-scCO2 formulation showed a significantly enhanced dissolution compared with LCDPsilica physical mixture and a faster dissolution rate than Lacipil® under different dissolution conditions. In an in vivo test, the area under concentration-time curve and Cmax of LCDP-scCO2 formulation was 9.23 and 23.78 fold greater than LCDP-silica physical mixture (1:15, w/w), respectively, whereas the corresponding values were 1.92 and 2.80 fold greater than Lacipil®, respectively. Our results showed that the solid dispersion prepared by supercritical fluids technology is a feasible method to enhance the oral bioavailability of LCDP.

Liposomes can serve as promising carriers for targeting delivery and controlled release of anti-cancer drugs. Doxorubicin-loaded liposomes have achieved enhanced efficacy in some solid tumors due to EPR effect with prolonged circulation and reduced toxicity. In this study the effects of liposomal structure have been investigated on the loading efficiency and controlled release behavior. Liposomes with various compositions were prepared through a thin film hydration method, and extruded to large unilamellar vesicles (LUVs) with mean particle size (Z ave~ 100 nm) by high-pressure extrusion technique. Then, doxorubicin was loaded into liposomes using remote active loading strategy. The loading efficiency and drug release behavior were evaluated using various parameters such as medium pH, liposome compositions and cholesterol concentrations. Liposomes prepared with different compositions showed high levels of drug encapsulation. Drug loading efficiencies (>90%) achieved with high final drug/lipid ratio (0.18-0.2). Faster release was observed at pH 5.5 when compared to pH 7.4 for all formulations. The fastest release rate was observed for unsaturated lipid (<48hr) and the slowest release rate was observed for saturated lipids with high phase transition temperature such as 1, 2-distearoylphosphatidylcholine (DSPC) and hydrogenated soy phosphatidylcholine (HSPC) (10-18 days). The sustained release was observed for liposomal formulations containing cholesterol. In conclusion, we have demonstrated that drug release rate could be controlled by manipulating the composition of liposomal structures.

Background: HIV/AIDS is a macrophage resident infection localized in the reticuloendothelial system and remote locations of brain and bone marrow. We present core shell nanoparticles of gold(AuNPs) and nevirapine(NVP) for targeted delivery to the multiple HIV reservoirs. The aim of the study was to design core shell NVP loaded AuNPs with high drug loading and to evaluate biodistribution of the nanoparticles in possible HIV reservoirs in vivo. A specific objective was to assess the possible synergy of AuNPs with NVP on anti-HIV activity in vitro. Method: Core shell nanoparticles were prepared by double emulsion solvent evaporation method and characterized. Results: Glyceryl monostearate-nevirapine-gold nanoparticles(GMS-NVP-AuNPs) revealed high entrapment efficiency (>70%), high loading (~40%), particle size <250 nm and zeta potential -35.9± 1.41mv and exhibited sustained release with good stability. Surface plasmon resonance indicated shell formation while SEM coupled EDAX confirmed the presence of Au. TEM confirmed formation of spherical core shell nanoparticles. GMS-NVP-AuNPs revealed low hemolysis (<10 %) and serum stability upto 6 h. GMS-NVP-AuNPs exhibited rapid, high and sustained accumulation in the possible HIV reservoir organs, including the major organs of liver, spleen, lymph nodes, thymus and also remote locations of brain, ovary and bone marrow. High cell viability and enhanced uptake in PBMC’s and TZM-bl cells were observed. While uptake in PBMC’s proposed monocytes/macrophages enabled brain delivery. GMS-NVP-AuNPs demonstrated synergistic anti-HIV activity. Conclusion: The superior anti-HIV activity in vitro coupled with extensive localization of the nanoparticles in multiple HIV reservoirs suggests great promise of the core shell GMS-NVP-AuNPs for improved therapy of HIV.

Background: Drug delivery through liposomes offers several advantages, but still challenging to the researchers for the use of liposomes as carriers in drug delivery due to their poor physical stability, unpredictable drug encapsulation and systemic availability of the loaded drug. Objective: The present investigation was planned with an objective to prepare Rifampicin loaded liposomes by using response surface methodology of statistical 32 factorial design and further to formulate them into pastilles for deliver through buccal route thereby to enhance systemic absorption. Methods: Rifampicin liposomes were prepared by using different ratios of soya lecithin and cholesterol by solvent Injection method. These liposomes were characterized by using optical microscopy, Scanning Electron Microscopy (SEM) and evaluated for particle size, entrapment efficiency (EE), in vitro and ex vivo drug release. Results: Main effects and interaction terms of the formulation variables were evaluated quantitatively using a mathematical statistical model approach showing that both independent variables have significant (P value < 0.05) effects on particle size (P value: 0.0273), percentage entrapment efficiency (P value: 0.0096), percentage drug release through dialysis membrane (P value: 0.0047) and percentage drug release through porcine buccal membrane (P value: 0.0019). Conclusion: The statistical factorial design of liposomal formulations fulfilled all the requirements of the target set and exhibited suitable values for the selected test parameters. Pastilles were prepared for liposomes using glycerol gelatin base and were found to be soft, smooth with uniform drug content and drug release.

Background: In this study, fluorescein labeled SLN and NLC formulations were prepared for improving the dermal distribution of the hydrophilic active ingredients and for enhancing the skin penetration. Methods: To determine skin distribution of the lipid nanoparticles ex-vivo penetration/ permeation experiments were performed using full thickness rat skin by means of Franz diffusion cells. Studies on the localization of fluorescence labeled nanoparticles were performed by confocal laser scanning microscopy (CLSM). Cellular uptake studies were performed on human keratinocyte cell line (HaCaT) and visualized by fluorescence microscope. Both tissue and cell uptake were also quantitatively determined by means of fluorimetric method in the skin extract or cell extract. Results: Both imaging and quantification studies suggest that the dermal localization of the lipid nanoparticles depends on their dimensions and particle size distribution. The CLSM images clearly show that the Tripalmitin based lipid nanoparticles have higher accumulation in the skin. It is possible to overcome the stratum corneum barrier function with T-NLC05 coded lipid nanoparticle formulation. Additionally cellular uptake of this NLC formulation is time dependent. Conclusıon: It can be concluded that this formulation is promising for treating local skin disorders without systemic side effects. On the other hand obtained results suggest that optimum formulation (T-NLC05) might be an interesting option even for novel cosmetic products.

Background: The oral bioavailability of Raloxifene hydrochloride, an FDA approved selective estrogen receptor modulator, is severely limited due to its poor aqueous solubility and extensive first pass metabolism. The Present work focuses on the development of ethosomal hydrogel for transdermal delivery of Raloxifene HCl as an alternate way to solve aforementioned problem. The physical breaching of stratum corneum, the principal barrier, by microneedle treatment was also employed to potentiate its transdermal permeation. Methods: The influence of lipid and ethanol concentration on vesicle size and entrapment efficiency was extensively investigated using response surface methodology based on central composite design. The software based optimization was done and validated using check point analysis. Optimized batch was extensively evaluated for its safety, efficacy and stability. Results: The optimized ethosomal batch possessed 403 nm size and 74.25% drug entrapment. Its zeta potential and in vitro drug release were also found favorable for transdermal permeation. The ex vivo skin permeation study revealed a transdermal flux of 4.621 μg/cm2/h through the intact pig ear skin which was further enhanced through the microporated skin (transdermal flux, 6.194 μg/cm2/h) with a 3.87 fold rise when compared to drug permeation from plain solution applied over intact skin (transdermal flux, 1.6 μg/cm2/h). Histopathological skin sections showed the non-irritant nature of the ethosomal hydrogel and microneedle treatment. The formulation was found stable under both refrigeration and room temperature conditions for 6 weeks. Conclusion: In a nutshell, the developed system was found efficient, safe and stable and seems promising for transdermal use.

Background: Atenolol has been used to treat angina and hypertension, either alone or with other antihypertensives. Despite its usefulness, it shows some side effects such as diarrhea and nausea in some patients. A method for slow release of atenolol in intestine is helpful to prevent such side effects. Methods: A facile co-precipitation microwave-assisted method was used to fabricate mesoporous hydroxyapatite nanoparticles (mHAp). It was then functionalized to have SO3H groups. The synthesized material was used for storage/slow release study of atenolol. Results: Atenolol loaded mHAp shows immediate release of atenolol in pH 8, whileafter functionalizing shows up to ca. 30% release at the beginning. In pH 1, 50% of drug was released after 10 h from AT@mHAp and after 18h the drug was almost completely released.The drug release profiles of functionalized HAp at pH value 1 and 8reveals the complete release of atenolol in intestine pH, while no complete release is observed in stomach environment. Conclusion: The aims of this work were synthesis and characterization of mesoporous HAp through the microwave-assisted co-precipitation method and elucidate the underlying drug release capability of mesoporous HAp nanoparticles. The SO3H group was incorporated into the mesoporous HAp and then used as drug delivery carriers using atenolol as a model drug to investigate their drug storage/release properties in simulated body fluid (SBF). Increasing pH value to 8 causes increase in the drug release.

Background: Amyotrophic Lateral Sclerosis (ALS), a motor neuron disease (MND), is a progressive neurodegenerative disorder characterized by the deterioration of both upper and lower motor neurons. Only one drug (riluzole) has been approved for the treatment of ALS. Riluzole is a BCS class II drug having 60% absolute bioavailability. It is a substrate of P-glycoprotein and BBB restricts its entry in brain. Objective: This investigation was aimed to develop O/W nanoemulsion system of riluzole to improve its brain bioavailability. Methods: Riluzole loaded nanoemulsion was prepared by phase titration method. It was consisting of 3% w/w Sefsol 218, 28.3% w/w Tween 80:Carbitol (1:1) and 68.7% w/w water. It was characterized for drop size, drop size distribution, transmittance, viscosity, pH, zeta potential, conductivity and nasal ciliotoxicity study. Thermodynamic stability and room temperature stability of prepared nanoemulsion formulation were evaluated. Pharmacokinetic and brain uptake study was carried out using albino rats (wistar) post intranasal and oral administration. Results: Riluzole loaded nanoemulsion was having a drop size of 23.92±0.52 nm. It was free from nasal ciliotoxicity and stable for three months. Brain uptake of riluzole post intranasal administration of riluzole loaded nanoemulsion was significantly (P <4.10 × 10-6) higher when it was compared with oral administration of riluzole loaded nanoemulsion. Conclusion: This study indicates that nanoemulsion of riluzole for intranasal administration could be a promising approach for the treatment of ALS to minimize the dose of riluzole in order to avoid dose related adverse events.

Background: The aim of this study was to determine the concentrations of propranolol in periocular tissues and plasma after ocular instillation of 0.5% propranolol gel-forming solution (GFS) as compared to 0.5% propranolol non-gelforming solution (non-GFS) for potential use in the treatment of periocular capillary hemangiomas. Methods: A GFS prepared in 1% sodium alginate or a non-GFS in phosphatebuffered saline was instilled into the eyes of rabbits. At predetermined time intervals after dosing, blood was withdrawn, rabbits were euthanized, and periocular tissues were dissected. Results: Ocular instillation of the GFS resulted in higher concentrations of propranolol in the outer layers of both the upper and lower eyelids (in the range of 9.9-36.9 μg/g) and maintained higher levels of propranolol in these tissues for 24 h after dosing, as compared to the ocular instillation of the non-GFS (in the range of 3.4-15.1 μg/g). While the concentrations of propranolol in the other periocular tissues were generally similar for GFS and non-GFS at 1 h after dosing, the concentrations of propranolol in the extraocular muscles and periocular fat were higher for GFS than those for non-GFS between 4-24 h after dosing. Lower level of propranolol in plasma was observed at 1 h with GFS as compared with non-GFS. Conclusion: The use of the propranolol gel-forming solution can prolong drug retention on the ocular surface and increase its distribution to the outer layers of the eyelids while decreasing systemic exposure to the drug.

Metronidazole is an antimicrobial agent utilized for the treatment of protozoa and anaerobic bacteria infections. Many times, it is necessary to modify the metronidazole release, and the development of modified release systems may be suggested. In this study, we are able to investigate the use of the residue normally thrown out from the preparation of propolis extracts (BP) as strategy to modify the metronidazole release. We prepared films containing polymeric adjuvant (gelatin or ethylcellulose) and metronidazole, by solvent casting method. Density, mechanical properties, water vapor permeability (WVP), moisture uptake capacity (MUC), thermogravimetry, differential scanning calorimetry, Fourier transform infrared spectroscopy (FT-IR), and in vitro metronidazole release were investigated. Thickness and density of the preparations indicated that the compounds were homogeneously dispersed throughout. Mechanical properties were influenced by film composition. Films containing gelatin showed higher resistance to stress while those containing ethylcellulose presented greater flexibility. The greater the adjuvant concentrations lower the resistance to rupture and the elasticity, but higher MUC and WVP of formulations. FT-IR tests suggested interactions between BP and the adjuvants. Films were capable to protect the metronidazole and changed its release profile. BP films are of great practical importance constituting a novel strategy to modify the metronidazole release.

Background: Microencapsulation of natural antioxidants in polymeric systems represents a possible strategy for improving the oral bioavailability of compounds that are otherwise poorly soluble. Objective: α-lipoic acid (ALA) was microencapsulated with polymethacrylate polymers (blends at various ratios of Eudragit® RS100 and RL100 resins). Method: Microspheres were produced by solvent displacement of an ethanol cosolution of ALA and polymers; the microsuspensions were then freeze-dried, using trehalose as a cryoprotector. Microspheres were characterized in the solid state for micromeritic properties and drug loading, as well as by infrared spectroscopy, powder X-ray diffractometry and differential scanning calorimetry. The antioxidant activity of free and encapsulated ALA was assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Results: In vitro release studies, performed in simulated gastric (pH 1.2) and intestinal fluid (pH 6.8), showed that, depending on polymer composition and drug-to-polymer ratio, ALA release can be slowed down, compared to the dissolution pattern of the free drug. Solid-state characterization confirmed the chemical stability of ALA in the microspheres, suggesting that ALA did not develop strong interactions with the polymer and was present in an amorphous or a disordered-crystalline state within the polymer network. As indicated by the DPPH assay, the microencapsulation of ALA in Eudragit® Retard matrices did not alter its antioxidant activity. Conclusion: ALA was effectively encapsulated in Eudragit® Retard matrices, showing a chemical stability up to 6 months at room conditions and at 40°C. Moreover, since the drug maintained its antioxidant activity in vitro, the potential application of these microparticulate systems for oral administration would deserve further studies.

Development of drug resistance to anticancer drugs is an important challenge for cancer treatment. Recent studies focus on co-delivery of anticancer drugs and siRNA to overcome this challenge. Mesoporous silica nanoparticles (MSNs) are one of the promising nanoparticles that enable the delivery of drugs and siRNA simultaneously. MSNs coated with copolymer capable of co-delivery of drug and siRNA were prepared and characterized. In the present study, MSNs functionalized with polyethylenimine-polyethylene glycol (PEI-PEG) copolymer were prepared. MSNs were characterized using dynamic light scattering (DLS), Transmission Electron Microscopy (TEM) and elemental analysis. Nanoparticles were loaded with epirubicin hydrochloride (EPI) and anti B-cell lymphoma 2 (BCL-2) siRNA. The in vitro cytotoxicity and in vivo efficacy of different formulations were evaluated. Mean size of MSNs ranged from 98 to 247 nm. EPI release from MSNs was pH-dependent. MSNs loaded with EPI and siRNA showed better in vitro cytotoxicity with 1 μg/mL EPI and 50-400 ng/mL siRNA, besides MSNs loaded with 9 mg/kg EPI and 1.2 mg/kg siRNA resulted in improved in vivo effects compared to EPI or MSNs containing EPI or siRNA alone. The results of in vitro and in vivo studies indicated the synergistic effect of EPI and anti BCL-2 siRNA. This formulation could be a promising nanoparticle for codelivery of drug and siRNA in cancer cells.