Stability-Enhanced Ternary Solid Dispersions of Glyburide: Effect of Preparation Method on Physicochemical Properties.

Introduction: Limited aqueous solubility and subsequent poor absorption and low bioavailability are the main challenges in oral drug delivery. Solid dispersion is a widely used formulation strategy to overcome this problem. Despite their efficiency, drug crystallization tendency and poor physical stability limited their commercial use. To overcome this defect, ternary solid dispersions of glyburide: sodium lauryl sulfate (SLS) and polyethylene glycol 4000 (PEG), were developed using the fusion (F) and solvent evaporation (SE) techniques and subsequently evaluated and compared. Materials and Methods: Physicochemical and dissolution properties of the prepared ternary solid dispersions were evaluated using differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), and dissolution test. Flow properties were also assessed using Carr's index and Hausner's ratio. The physical stability of the formulations was evaluated initially and after 12 months by comparing dissolution properties. Results: Formulations prepared by both methods similarly showed significant improvements in dissolution efficiency and mean dissolution time compared to the pure drug. However, formulations that were prepared by SE showed a greater dissolution rate during the initial phase of dissolution. Also, after a 12-month follow-up, no significant change was observed in the mentioned parameters. The results of the infrared spectroscopy indicated that there was no chemical interaction between the drug and the polymer. The absence of endotherms related to the pure drug from thermograms of the prepared formulations could be indicative of reduced crystallinity or the gradual dissolving of the drug in the molten polymer. Moreover, formulations prepared by the SE technique revealed superior flowability and compressibility in comparison with the pure drug and physical mixture (ANOVA, P < 0.05). Conclusion: Efficient ternary solid dispersions of glyburide were successfully prepared by F and SE methods. Solid dispersions prepared by SE, in addition to increasing the dissolution properties and the possibility of improving the bioavailability of the drug, showed acceptable long-term physical stability with remarkably improved flowability and compressibility features.

Dissolution improvement of binary solid dispersions of erlotinib prepared by one-step electrospray method.

Erlotinib hydrochloride, a selective tyrosine kinase inhibitor approved for treatment of non-small cell lung cancer firstly. Erlotinib classified as class II drugs in the Biopharmaceutical Classification System (BCS), which characterized by low solubility and high permeability. The aim of this study was to enhance the dissolution rate of this drug. The binary solid dispersions of erlotinib: PVP prepared at different ratios (1:3, 1:5, and 1:8) by electrospray technique. The characterization of formulations performed using differential scanning calorimetery (DSC), Fourier transform infrared spectroscopy (FT-IR) and dissolution rate test. The dissolution results showed that the dissolution rate of erlotinib from binary solid dispersions improved in comparison to pure drug. FTIR spectrum results showed that all peaks of erlotinib functional groups are also observable in the prepared solid dispersions. The FTIR results demonstrated that there was no interaction between drug and polymer. DSC thermograms of the prepared solid dispersions showed no drug-related peak, which is probably related to reduced crystallinity and drug amorphization. Based on the obtained results, it can be concluded that the erlotinib solid dispersion systems displayed improved dissolution rate compared to the pure drug. This will likely lead to increased drug bioavailability.

Novel Approaches for Efficient Delivery of Tyrosine Kinase Inhibitors.

Epidermal growth factor receptors (EGFRs) have potential to be considered as therapeutic target for cancer treatment especially in cancer patients with overexpression of EGFR. Cetuximab as a first monoclonal antibody and Imatinib as the first small molecule tyrosine kinase inhibitor (SMTKI) were approved by FDA in 1998 and 2001. About 28 SMTKIs have been approved until 2015 and a large number of compound with kinase inhibitory activity are at the different phases of clinical trials. Although Kinase inhibitors target specific intracellular pathways, their tissue or cellular distribution are not specific. So treatment with these drugs causes serious dose dependent side effects. Targeted delivery of kinase inhibitors via dendrimers, polymeric nanoparticles, magnetic nanoparticles and lipid based delivery systems such as liposomes, solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) can lead to reduction of side effects and improving therapeutic efficacy of the drugs in the target organs. Furthermore formulation of these drugs is challenged by their physicochemical properties such as solubility and dissolution rate. The main approaches in order to increase dissolution rate, are particle size reduction, self-emulsification, cyclodextrin complexation, crystal modification and amorphous solid dispersion. Synergistic therapeutic effect, decreased side effects and drug resistant, reduced cost and increased patient compliance are the advantages associated with using combination therapy especially in the treatment of cancer. Combination of TKIs with chemotherapeutic agents or biopharmaceuticals such as monoclonal antibodies and oligonucleotides and also combination of two TKIs within one formulation is possible by new targeting delivery systems. This article reviews the recent advances in the design and development of delivery systems for TKIs.

Synthesis of PCEC Copolymers with Controlled Molecular Weight Using Full Factorial Methodology.

PURPOSE: Polycaprolactone (PCL) is a biodegradable polyester and has attracted attention as a suitable carrier for development of controlled drug delivery due to its non-toxicity and biocompatibility. It has been reported that the biodegradability of PCL can be enhanced by copolymerization with PEG. Molecular weight (Mw) and CL block lengths optimization in a series of synthesized PCEC copolymers was the main purpose of this study. METHODS: The composition of copolymers was designed using full factorial methodology. Molecular weight of used PEG (4 levels) and weight ratio of epsilon-caprolactone/PEG (3 levels) were selected as independent variables. The PCEC copolymers were synthesized by ring opening polymerization. Formation of copolymers was confirmed by FT-IR spectroscopy as well as H-NMR. The Mn of PCEC copolymers was calculated from HNMR spectra. The thermal behavior of copolymers was characterized on differential scanning calorimeter. RESULTS: Molecular weight of twelve synthesized copolymers was ranged from 1782 to 9264. In order to evaluate the effect of selected variables on the copolymers composition and Mw, a mathematical model for each response parameter with p-value less than 0.001were obtained. Average percent error for prediction of total Mn of copolymers and Mn of CL blocks were 13.81% and 14.88% respectively. CONCLUSION: In conclusion, the proposed model is significantly valid due to obtained low percent error in Mn prediction of test sets.

Preparation of Chlorpheniramine Maleate-loaded Alginate/Chitosan Particulate Systems by the Ionic Gelation Method for Taste Masking.

BACKGROUND: Chlorpheniramine maleate (CM) is widely used as an antihistaminic drug but it is very bitter and as yet no mouth dissolving/disintegrating taste-masked preparation that might be useful for pediatric and geriatric patients is available in the market. OBJECTIVES: The purpose of this research was to mask the bitter taste of CM by formulating microspheres of the taste-masked drug. MATERIALS AND METHODS: This work was done to develop alginate/chitosan particles prepared by ionic gelation (Ca(2+) and Al(3+)) for the CM release. The effect of different chitosan and Ca(2+) concentrations on taste masking and the characteristics of the microspheres were investigated. Ca(2+) and Al(3+) alginates microspheres of CM were prepared using cross-linked insoluble complexes that precipitate, incorporating the drug. Formulations were characterized for particle size and shape, entrapment efficiency, fourier transform spectroscopy (FTIR), x-ray diffraction (XRD), and differential scanning calorimetry (DSC), bitter taste threshold and in vitro drug release in simulated gastrointestinal fluids. RESULTS: FTIR, XRD and DSC demonstrated unstable characters of CM in the drug-loaded microspheres and revealed an amorphous form. Also, the peak of alginate microparticles (Ca(2+) and Al(3+) ions) in all formulations remained the same, with low intensity of spectrum. The results of DSC, X-ray diffraction and FTIR showed the presence of several CM chemical interactions with alginate and ions (Ca(2+) and Al(3+)). The microsphere formulations showed desirable drug entrapment efficiencies (62.2-94.2%). Calcium/aluminum alginate retarded the release of CM at low pH = 1.2 and released the drug from microspheres slowly at pH = 6.8, simulating intestine pH. The drug release duration and the release kinetics were dependent on the nature of the polymers, the cation concentrations, and valences (Ca(2+) and Al(3+)). The drug release rate was decreased by an increase in chitosan and cation concentrations. CONCLUSIONS: The results of the present study indicated that oral preparation of CM with an acceptable taste is feasible.

Synthesis, characterization and in vitro anti-tumoral evaluation of Erlotinib-PCEC nanoparticles.

BACKGROUND: Development of a nanosized polymeric delivery system for erlotinib was the main objective of this research. MATERIALS AND METHODS: Poly caprolactone-polyethylene glycol-polycaprolactone (PCEC) copolymers with different compositions were synthesized via ring opening polymerization. Formation of triblock copolymers was confirmed by HNMR as well as FT-IR. Erlotinib loaded nanoparticles were prepared by means of synthesized copolymers with solvent displacement method. RESULTS: Physicochemical properties of obtained polymeric nanoparticles were dependent on composition of used copolymers. Size of particles was decreased with decreasing the PCL/PEG molar ratio in used copolymers. Encapsulation efficiency of prepared formulations was declined by decreasing their particle size. Drug release behavior from the prepared nanoparticles exhibited a sustained pattern without a burst release. From the release profiles, it can be found that erlotinib release rate from polymeric nanoparticles is decreased by increase of CL/PEG molar ratio of prepared block copolymers. Based on MTT assay results, cell growth inhibition of erlotinib has a dose and time dependent pattern. After 72 hours of exposure, the 50% inhibitory concentration (IC50) of erlotinib hydrochloride was appeared to be 14.8 µM. CONCLUSIONS: From the obtained results, it can be concluded that the prepared PCEC nanoparticles in this study might have the potential to be considered as delivery system for erlotinib.

Modified synthesis of erlotinib hydrochloride.

PURPOSE: An improved and economical method has been described for the synthesis of erlotinib hydrochloride, as a useful drug in treatment of non-small-cell lung cancer. METHOD: Erlotinib hydrochloride was synthesized in seven steps starting from 3, 4-dihydroxy benzoic acid. In this study, we were able to modify one of the key steps which involved the reduction of the 6-nitrobenzoic acid derivative to 6-aminobenzoic acid derivative. An inexpensive reagent such as ammonium formate was used as an in situ hydrogen donor in the presence of palladium/charcoal (Pd/C) instead of hydrogen gas at high pressure. RESULT: This proposed method proceeded with 92% yield at room temperature. Synthesis of erlotinib was completed in 7 steps with overall yield of 44%. CONCLUSION: From the results obtained it can be concluded that the modified method eliminated the potential danger associated with the use of hydrogen gas in the presence of flammable catalysts. It should be mentioned that the catalyst was recovered after the reaction and could be used again.

Polymer Percolation Threshold in Multi-Component HPMC Matrices Tablets.

INTRODUCTION: The percolation theory studies the critical points or percolation thresholds of the system, where one component of the system undergoes a geometrical phase transition, starting to connect the whole system.The application of this theory to study the release rate of hydrophilic matrices allows to explain the changes in release kinetics of swellable matrix type system and results in a clear improvement of the design of controlled release dosage forms. METHODS: In this study, the percolation theory has been applied to multi-component hydroxypropylmethylcellulose (HPMC) hydrophilic matrices. Matrix tablets have been prepared using phenobarbital as drug, magnesium stearate as a lubricant employing different amount of lactose and HPMC K4M as a filler and matrix forming material, respectively. Ethylcelullose (EC) as a polymeric excipient was also examined. Dissolution studies were carried out using the paddle method.In order to estimate the percolation threshold, the behaviour of the kinetic parameters with respect to thevolumetric fraction of HPMC at time zero, was studied. RESULTS: In both HPMC/lactose and HPMC/EC/lactose matrices, from the point of view of the percolation theory, the optimum concentration for HPMC, to obtain a hydrophilic matrix system for the controlled release of phenobarbital is higher than 18.1% (v/v) HPMC. Above 18.1% (v/v) HPMC, an infinite cluster of HPMC would be formed maintaining integrity of the system and controlling the drug release from the matrices. According to results, EC had no significant influence on the HPMC percolation threshold. CONCLUSION: This may be related to broad functionality of the swelling hydrophilic matrices.

Synthesis and determination of acute and chronic pain activities of 1-[1-(3-methylphenyl) (tetralyl)]piperidine as a new derivative of phencyclidine via tail immersion and formalin tests.

Phencyclidine (1-(1-phenylcyclohexyl)piperidine, CAS 956-90-1, PCP, 1) and ketamine (2-O-chlorophenyl-2-methylaminocyclohexan, CAS 1867-66-9, II) revealed some analgesic effects. Some of their derivatives have been synthesized for biological properties studies. Utilizing 1-tetralone as a starting material, 1-[1-(3-methylphenyl)(tetralyl)]piperidine, (PCP-CH3-tetralyl, III) was synthesized and its analgesic effects were studied on rats via tail immersion (as a model of acute thermal pain) and formalin (as a model of acute chemical and chronic pain) tests and compared with those of ketamine and PCP. The results indicated a marked anti-nociception 2-25 min after ketamine injection, but this analgesic effect lasted for 40 min following PCP-CH3-tetralyl application in the tail immersion test. However, the data obtained from the formalin test showed that chronic pain could be significantly attenuated by ketamine, PCP and PCP-CH3-tetralyl.

Synthesis and determination of chronic and acute thermal and chemical pain activities of a new derivative of phencyclidine in rats.

Phencyclidine (1-(1-phenylcyclohexyl) piperidine, PCP, I) and ketamine (2-O-chlorophenyl-2-methylaminocyclohexan, II) have shown analgesic effects. Some of its derivatives were synthesized and their biological properties have been studied. In this study, a new derivative of PCP, (1-[1-(3-methoxyphenyl) (tetralyl)] piperidine, PCP-OCH3-tetralyl, III) was synthesized and the acute thermal pain of this compound was determined using tail immersion test on rats and the results were compared with Ketamine and PCP. The results indicated a marked anti-nociception 2-25 min after ketamine injection, but the analgesic effect remained for 40 min following PCP-OCH3-tetralyl application in tail immersion test. However, the data obtained from formalin test showed that the chronic anti-nociception effect of ketamine was higher than PCP and PCP-OCH3-tetralyl exhibited almost similar analgesic effect.

Bioequivalence of fexofenadine tablet formulations assessed in healthy Iranian volunteers.

BACKGROUND AND OBJECTIVE: Many drug products containing the same amount of active drug are made and marketed by more than one pharmaceutics manufacturer. Since the quality of final drug product is affected by the source of ingredients, type and amount of excipients and manufacturing process, bioequivalence studies are used to determine the bioavailability and characterize the pharmacokinetics of the new formulation relative to a reference formulation. In the present study the bioavailability of a new capsule formulation of fexofenadine (CAS 153439-40-8) was compared to a reference formulation in 12 healthy male volunteers. METHODS: The blood samples were collected at different time points. After centrifugation and decanting the plasma, the drug was extracted using a mixture of diethyl ether/isopropyl alcohol (5:95% v/v). Then the samples were dried at 45 degrees C under nitrogen and finally, after dissolving the dried sample in mobile phase, the plasma drug concentrations were determined using HPLC. The pharmacokinetic parameters (Cmax, AUCt0, AUCinfinity0) were statistically compared by analysis of variance (ANOVA) for test and reference formulations and no statistical differences were observed. RESULTS AND DISCUSSION: The maximum plasma concentration (Cmax) of fexofenadine was 1206.3 +/- 619.0 ng/ml for the test and 1172.6 +/- 493.7 ng/ml for the reference formulation. The mean AUC0-infinity of fexofenadine was 8911.4 +/- 3870.0 and 9363.9 +/- 2668.0 ng x h/ml for the test and reference formulation, respectively. The calculated 90% confidence intervals for the mean test/reference ratios of mentioned parameters were 90.0-113.9, 86.9-109.5 and 80.8-102.8, respectively, which are in the bioequivalence range. CONCLUSION: Based on the obtained results the two fexofenadine formulations are considered to be equivalent.