Search

Celastrol (CL), a bioactive compound isolated from Tripterygium wilfordii, has demonstrated bioactivities against a variety of diseases including cancer and obesity. However, its poor water solubility and rapid in vivo clearance limit its clinical applications. To overcome these limitations, nanotechnology has been employed to improve its pharmacokinetic properties. Nanoparticles made of biological materials offer minimal adverse effects while maintaining the efficacy of encapsulated therapeutics. Silk fibroin (SF) solution was prepared successfully by extraction from the cocoons of silkworms, and a final concentration of 2 mg/mL SF solution was used for the preparation of CL-loaded SF nanoparticles (CL-SFNP) by the desolvation method. A stirring speed of 750 rpm and storage time of 20 h at &minus, 20 &deg, C resulted in optimized product yield. A high-performance liquid chromatography (HPLC) method was developed and validated for the analysis of CL in rat plasma in terms of selectivity, linearity, intra-/inter-day precision and accuracy, and recovery. No interference was observed in rat plasma. Linearity in the concentration range of 0.05&ndash, 5 &micro, g/mL was observed with R2 of 0.999. Precision and accuracy values were below the limit of acceptance criteria, i.e., 15% for quality control (QC) samples and 20% for lower limit of quantification (LLOQ) samples. Rats were given intravenous (IV) administration of 1 mg/kg of pure CL in PEG 300 solution or CL-SFNP. The pharmacokinetic profile was improved with CL-SFNP compared to pure CL. Pure CL resulted in a maximum concentration (Cmax) value of 0.17 &micro, g mL&minus, 1 at 5 min following administration, whereas that for CL-SFNP was 0.87 &micro, 1 and the extrapolated initial concentrations (C0) were 0.25 and 1.09 &micro, 1, respectively, for pure CL and CL-SFNP. A 2.4-fold increase in total area under the curve (AUC0-inf) (&micro, g h mL&minus, 1) was observed with CL-SFNP when compared with pure CL. CL-SFNP demonstrated longer mean residence time (MRT, 0.67 h) than pure CL (0.26 h). In conclusion, the preparation of CL-SFNP was optimized and the formulation demonstrated improved pharmacokinetic properties compared to CL in solution following IV administration.

The objective of the present study was to develop a proliposomal formulation to increase the oral bioavailability of dronedarone hydrochloride (dronedarone HCl) by enhancing solubility, dissolution, and/or intestinal absorption. Proliposomes were prepared by using solvent evaporation method. In this process, different ratios of drug, phospholipids, such as soy phosphatidylcholine (SPC), Phospholipon 90H, hydrogenated egg phosphatidylcholine (HEPC), and dimyristoyl phosphatidylglycerol (DMPG), and cholesterol were used. Physical characterization and in vitro dissolution studies were evaluated for the prepared formulations. In vitro transport across the membrane was carried out using Caco-2 cells. Among all the formulations, the amount of drug released in dissolution was higher with DPF8 formulation (drug:DMPG Na:cholesterol:::1:2:0.2) compared to the pure drug. Also, Caco-2 cell permeability studies resulted in 2.6-fold increase in apparent permeability. Optimized formulation was evaluated in vivo in male Sprague-Dawley rats. After single oral administration of optimized formulation (DPF8), a relative bioavailability of 148.36% was achieved compared to the pure drug. Improved oral bioavailability of dronedarone could be provided by an optimized proliposomal formulation with enhanced solubility, permeability, and oral absorption.

The objective of this study was to develop proliposomal formulation and self micro-emulsifying drug delivery system (SMEDDS) for a poorly bioavailable drug, nisoldipine and to compare their in vivo pharmacokinetics. Proliposomes were prepared by thin film hydration method using different lipids such as Soy phosphatidylcholine (SPC), Hydrogenated Soy phosphatidylcholine (HSPC), Dimyristoylphosphatidylcholine (DMPC) and Dimyristoyl phosphatidylglycerol sodium (DMPG), Distearyl phosphatidylcholine (DSPC), and Cholesterol in various ratios. SMEDDS formulations were prepared using varying concentrations of Capmul MCM, Labrasol, Cremophor EL and Tween 80. Both proliposomes and SMEDDS were evaluated for particle size, zeta potential, in vitro drug release, in vitro permeability and in vivo pharmacokinetics. In vitro drug release was carried out in purified water using USP type II dissolution apparatus. In vitro drug permeation was studied using parallel artificial membrane permeation assay (PAMPA) and everted rat intestinal perfusion techniques. In vivo pharmacokinetic studies were conducted in male Sprague-Dawley rats. Among the different formulations, proliposomes with drug:DMPC:cholesterol in the ratio of 1:2:0.5 and SMEDDS with Capmul MCM (13.04% w/w), Labrasol (36.96% w/w), Cremophor EL (34.78% w/w) and Tween 80 (15.22% w/w) demonstrated the desired particle size and zeta potential. Enhanced drug release was observed with proliposomes and SMEDDS compared to pure nisoldipine in purified water after 1h. Nisoldipine permeability across PAMPA and everted rat intestinal perfusion models was significantly higher with proliposomes and SMEDDS. Following single oral administration of proliposomes and SMEDDS, a relative bioavailability of 301.11% and 239.87% respectively, was achieved compared to pure nisoldipine suspension.

Lipids have been extensively used in formulations to enhance dissolution and bioavailability of poorly water-soluble as well as water-soluble drug molecules. The digestion of lipid-based formulations, in the presence of bile salts, phospholipids, and cholesterol, changes the lipid composition in vivo, resulting in the formation of different colloidal phases in the intestine. Therefore, in vitro characterization and evaluation of such formulations are critical in developing a successful formulation. This review covers comprehensive discussion on in vitro characterization techniques such as solubility, drug entrapment, thermal characterization, dissolution, and digestion of lipid-based formulations.

The objective of this study was to develop proliposomes and self-nanoemulsifying drug delivery system (SNEDDS) for a poorly bioavailable drug, valsartan, and to compare their in vivo pharmacokinetics. Proliposomes were prepared by thin-film hydration method using different lipids such as soy phosphatidylcholine (SPC), hydrogenated soy phosphatidylcholine (HSPC), distearyl phosphatidylcholine (DSPC), dimyristoylphosphatidylcholine (DMPC), and dimyristoyl phosphatidylglycerol sodium (DMPG) and cholesterol in various ratios. SNEDDS formulations were prepared using varying concentrations of capmul MCM, labrafil M 2125, and Tween 80. Both proliposomes and SNEDDS were evaluated for particle size, zeta potential, in vitro drug release, in vitro permeability, and in vivo pharmacokinetics. In vitro drug release was carried out in purified water and 0.1 N HCl using USP type II dissolution apparatus. In vitro drug permeation was studied using parallel artificial membrane permeation assay (PAMPA) and everted rat intestinal permeation techniques. Among the formulations, the proliposomes with drug/DMPG/cholesterol in the ratio of 1:1:0.5 and SNEDDS with capmul MCM (16.0% w/w), labrafil M 2125 (64.0% w/w), and Tween 80 (18.0% w/w) showed the desired particle size and zeta potential. Enhanced drug release was observed with proliposomes and SNEDDS as compared to pure valsartan. Valsartan permeability across PAMPA and everted rat intestinal permeation models was significantly higher with proliposomes and SNEDDS. Following single oral administration of proliposomes and SNEDDS, a relative bioavailability of 202.36 and 196.87%, respectively, was achieved compared to pure valsartan suspension. The study results indicated that both proliposomes and SNEDDS formulations are comparable in improving the oral bioavailability of valsartan.

Insoluble drugs often formulated with various excipients to enhance the dissolution. Cyclodextrins (CDs) are widely used excipients to improve dissolution profile of poorly soluble drugs. Drug-CD complexation process is complex and often requires multiple processes to produce solid dosage form. Hence, this study explored commonly used granulation processes for simultaneous complexation and granulation. Poorly soluble drugs ibuprofen and glyburide were selected as experimental drugs. Co-evaporation of drug:CD mixture from a solvent followed by wet granulation with water was considered as standard process for comparison. Spray granulation and fluid bed processing (FBP) using drug:CD solution in ethanol were evaluated as an alternative processes. The dissolution data of glyburide tablets indicated that tablets produced by spray granulation, FBP and co-evaporation-granulation have almost identical dissolution profile in water and 0.1% SLS (>70% in water and >60% in SLS versus 30 and 34%, respectively for plain tablet, in 120 min). Similarly, ibuprofen:CD tablets produced by co-evaporation-granulation and FBP displayed similar dissolution profile in 0.01 M HCl (pH 2.0) and buffer pH 5.5 (>90 and 100% versus 44 and 80% respectively for plain tablets, 120 min). Results of this study demonstrated that spray granulation is simple and cost effective process for low dose poorly soluble drugs to incorporate drug:CD complex into solid dosage form, whereas FBP is suitable for poorly soluble drugs with moderate dose.

Proliposomes are phospholipid based drug delivery systems that are finding important applications in the field of pharmaceutics. Proliposomes have been extensively studied as a potential carrier for oral delivery of drugs with poor bioavailability, but the mechanism of absorption and cellular uptake pathways has not yet been clearly understood. An in-depth insight into the physical and biological behavior of proliposomes is necessary for designing an effective delivery system for enhancing the availability of drug at the intended site. Reformulation of sub optimal drugs using proliposomes has given an opportunity to improve the therapeutic indices of various drugs predominantly by altering their uptake mechanism. This work reviews the proliposomal drug delivery field, summarizes the success of proliposomes for the oral delivery of drugs with poor bioavailability; indicating the key issues to be addressed to affirm that proliposomes can effectively work as a drug carrier in clinical settings with a clear understanding of its behavior in biological environment, as they are now an established platform technology with considerable clinical acceptance.

The aim of this study was to develop a proliposomal formulation of lipopeptide antibiotic drug daptomycin (DAP) for oral delivery. Thin film hydration was the selected method for preparation of proliposomes. Different phospholipids including soy-phosphatidylcholine (SPC), hydrogenated egg-phosphatidylcholine (HEPC), and distearoyl-phosphatidylcholine (DSPC) were evaluated in combination with cholesterol. The inclusion of surface charge modifiers in the formulation such as dicetyl phosphate (DCP) and stearylamine (SA) to enhance drug encapsulation was also evaluated. Particle size, surface charge, and encapsulation efficiency were performed on daptomycin-hydrated proliposomes as part of physical characterization. USP type II dissolution apparatus with phosphate buffer (pH 6.8) was used for in vitro drug release studies. Optimized formulation was evaluated for in vivo pharmacokinetics after oral administration to Sprague-Dawley rats. Proliposomes composed of SPC exhibited higher entrapment efficiency than those containing HEPC or DSPC. The highest entrapment efficiency was achieved by positively charged SPC-SA proliposomes, showing an encapsulation efficiency of 92% and a zeta potential of + 28 mV. In vitro drug release of optimized formulation demonstrated efficient drug retention totaling for less than 20% drug release within the first 60 min and only 42% drug release after 2 h. Pharmacokinetic parameters after single oral administration of optimized proliposomal formulation indicated a significant increase in oral bioavailability of DAP administered as SPC-SA proliposomes when compared to drug solution. Based on these results, incorporation of charge modifiers into proliposomes may increase drug loading and proliposomes an attractive carrier for oral delivery of daptomycin.

Drug discovery and development has become longer and costlier process. The fear of failure and stringent regulatory review process is driving pharmaceutical companies towards “me too” drugs and improved generics (505(b) (2)) fillings. The discontinuance of molecules at late stage clinical trials is common these years. The molecules are withdrawn at various stages of discovery and development process for reasons such as poor ADME properties, lack of efficacy and safety reasons. Hence this review focuses on possible applications of formulation and drug delivery to salvage molecules and improve the drugability. The formulation and drug delivery technologies are suitable for addressing various issues contributing to attrition are discussed in detail., Graphical abstract This paper provides insight into effective application of formulation strategies to reduce attrition of molecules during drug discovery/development. Comprehensive information on utilizing solubilzation, prodrug, proliposomes, polymer conjugation, targeted/timed release formulations, alternate routes of delivery to reduce attrition of molecules due to ADME, efficacy and toxicity issues is provided. Clinical success and challenges are documented.

The aim of this study was to develop and characterize phospholipid bearing pellets for a poorly water-soluble drug, nisoldipine. Pellets were prepared using extrusion-spheronization technique containing microcrystalline cellulose, soy phosphatidylcholine (SPC), granulating fluid and lactose. Operational parameters such as extrusion speed, spheronization speed and residence time were evaluated. Optimal extrusion speed was found to be 50 rpm with a spheronization speed of 60 Hz and residence time of 2 min. Pellets were characterized for their size, shape, density, flow properties, friability, moisture content, surface morphology and thermal properties. Pellets were evaluated for their assay and in vitro drug release. Mathematical modeling was used to determine the release patterns of the pellets. Pellets were found to be spherical, 600-850 μm size with0.01% friability and had70% yield. Scanning electron microscopic (SEM) studies showed a smoother external surface and a porous internal matrix. SPC incorporated pellets resulted in improved dissolution of the drug. Pellets with SPC (20 and 30%) released90% of the drug within 24 h. The dissolution profiles of the pellets were best fitted to Korsmeyer-Peppas kinetic model. In this study, we could successfully incorporate a lipid and a water-insoluble drug into a pellet formulation with improved dissolution profile.

Advances in polymer science have led to the development of novel drug delivery systems. Some polymers are obtained from natural resources and then chemically modified for various applications, while others are chemically synthesized and used. A large number of natural and synthetic polymers are available. In the present paper, only water soluble polymers are described. They have been explained in two categories (1) synthetic and (2) natural. Drug polymer conjugates, block copolymers, hydrogels and other water soluble drug polymer complexes have also been explained. The general properties and applications of different water soluble polymers in the formulation of different dosage forms, novel delivery systems and biomedical applications will be discussed.

Pneumonia due to methicillin-resistant Staphylococcus aureus (MRSA) often cannot be cured by vancomycin treatment. Poor lung tissue and intracellular penetration limits the ability to achieve effective bactericidal levels, particularly in alveolar macrophages, where MRSA can evade phagocytic killing. Compared to standard formulations, liposome encapsulation has been shown to enhance vancomycin intracellular killing of MRSA. In this murine pharmacokinetic and biodistribution study, PEGylated liposomal vancomycin, compared to standard and non-PEGylated formulations, significantly prolonged blood circulation time and increased deposition in lung, liver, and spleen and yet reduced accumulation in kidney tissue. As a result of optimizing antimicrobial targeting of infected lung tissue and limiting renal parenchymal exposure, administration of PEGylated liposomal vancomycin may improve the efficacy of treatment of MRSA pneumonia and reduce the risk of nephrotoxicity.

Meticillin-resistant Staphylococcus aureus (MRSA) can persist in alveolar macrophages and contribute to clinical failure of intravenous vancomycin to cure pneumonia. In this study, it was shown that vancomycin in standard solution is unable to kill intracellular MRSA within macrophages. The intracellular viability of MRSA inside macrophages treated with two different formulations of encapsulated liposomal vancomycin prepared using a hydration-dehydration method was then determined. In contrast to the observations with standard vancomycin, treatment with conventional non-pegylated liposomal vancomycin (lacking any surface modification) resulted in a sufficient concentration of antibiotic inside the intracellular compartment of the macrophages to exert a marked bactericidal effect against MRSA. On the other hand, treatment of infected macrophages with surface-pegylated liposomes resulted in no impact on MRSA survival, and this lack of an inhibitory effect may likely reflect delayed phagocytosis owing to the 'stealth' effect by pegylation. This study indicates the potential for a novel liposomal delivery system that may improve clinical vancomycin treatment outcomes by targeting intracellular MRSA infection.

Objective and design A 6-month, randomized clinical study was conducted to evaluate the effect of a ribonuclease-enriched lactoferrin (R-ELF) supplement on the circulating cytokine levels and bone health of postmenopausal women. Subjects Thirty-eight healthy postmenopausal women, aged 45–60 years, were randomized into placebo and R-ELF groups. Treatment The R-ELF group was supplemented with R-ELF (2 9 125 mg/day) and calcium (100% RDA), while the placebo group received only the calcium supplement. Methods Serum levels of receptor activator for NF-jB ligand (RANKL), C-reactive protein (CRP) and various pro- and anti-inflammatory cytokines were determined by ELISA. Results Pro-inflammatory cytokines IL-6 and TNF-a decreased significantly (-44 and -10%, respectively) while anti-inflammatory IL-10 increased (140%) due to R-ELF supplementation at the end of study. RANKL and CRP were modestly reduced (-50%) relative to their placebo levels, although RANKL elevated initially. Conclusions R-ELF supplementation showed beneficial effects towards improvement of inflammatory status in postmenopausal women.

The efficacy of n-lauryl-beta-D-maltopyranoside, (dodecylmaltoside, DDM) as a permeability-enhancer for tiludronate and cromolyn (BCS Class III, water-soluble compounds with oral bioavailability5%) was evaluated in Caco-2 cell monolayers and rat intestinal sacs. In Caco-2 cells samples were collected over a 5-h period and transepithelial resistance (TEER) was measured concurrently. In rat intestinal sacs, samples of the test compounds and marker (Lucifer Yellow) were collected over a 40 min period; accumulation in the serosal fluid and intestinal tissue was measured. At lower concentration DDM had no effect on cromolyn permeability and a marginal increase was observed at higher concentration. Tiludronate permeability in the presence of DDM showed greater enhancement as compared to cromolyn. At higher concentration DDM appeared to cause permanent damage to the cell monolayer (irreversible change in TEER). In the intestinal tissue, DDM caused increased tissue accumulation of test compounds. This indicated that transport was not restricted to the paracellular route and damage to the intestinal tissue could not be ruled out. Based on the results obtained in this study it can be concluded that at concentrations that are non-toxic DDM appears to have a limited use to improve the oral absorption of cromolyn and tiludronate.

Current treatments for postmenopausal osteoporosis suffer from side effects. Safe and natural milk proteins, ribonuclease, and lactoferrin promote formation of new capillaries and bone formation. A ribonuclease-enriched lactoferrin supplement studied here, demonstrates significant reduction in resorption and increase in formation, towards restoring the balance of bone turnover within 6 months. Osteoporosis, a major health issue among postmenopausal women, causes increased bone resorption and reduced bone formation. A reduction in angiogenesis could also contribute to this imbalance. Current treatments such as hormone replacement therapy and bisphosphonates have drawbacks of severe side effects. Milk ribonuclease (RNase) is known to promote angiogenesis and lactoferrin (LF) to stimulate bone formation by osteoblasts. We examine the effect of ribonuclease-enriched lactoferrin supplement on the bone health of postmenopausal women. A total of 38 healthy, postmenopausal women, aged 45 to 60 years were randomized into placebo or RNAse-enriched-LF (R-ELF) supplement groups. The bone health status was monitored by assessing bone resorption markers, serum N-telopeptides (NTx), and urine deoxypyridinoline (Dpd) crosslinks and serum bone formation markers, bone-specific alkaline phosphatase (BAP), and osteocalcin (OC). R-ELF supplementation demonstrated a decrease in urine Dpd levels by 14% (19% increase for placebo) and serum NTx maintained at 24% of the baseline (41% for placebo), while serum BAP and OC levels showed a 45% and 16% elevation (25% and 5% for placebo). R-ELF supplementation demonstrated a statistically significant reduction in bone resorption and increase in osteoblastic bone formation, to restore the balance of bone turnover within a short period.

The objective of this study was to develop proliposomal formulation for a poorly bioavailable drug, tacrolimus. Proliposomes were prepared by thin film hydration method using different lipids such as hydrogenated soy phosphatidylcholine (HEPC), soy phosphatidylcholine (SPC), distearyl phosphatidylcholine (DSPC), dimyristoylphosphatidylcholine (DMPC), and dimyristoylphosphatidylglycerol sodium (DMPG) and cholesterol in various ratios. Proliposomes were evaluated for particle size, zeta potential, in vitro drug release, in vitro permeability, and in vivo pharmacokinetics. In vitro drug release was carried out in purified water using USP type II dissolution apparatus. In vitro drug permeation was studied using parallel artificial membrane permeation assay (PAMPA) and everted rat intestinal perfusion techniques. In vivo pharmacokinetic studies were conducted in male Sprague-Dawley (SD) rats. Among the different formulations, proliposomes with drug/DSPC/cholesterol in the ratio of 1:2:0.5 demonstrated the desired particle size and zeta potential. Enhanced drug release was observed with proliposomes compared to pure tacrolimus in purified water after 1 h. Tacrolimus permeability across PAMPA and everted rat intestinal perfusion models was significantly higher with proliposomes. The optimized formulation of proliposomes indicated a significant improvement in the rate and absorption of tacrolimus. Following a single oral administration, a relative bioavailability of 193.33% was achieved compared to pure tacrolimus suspension.

The objective of our investigational work was to develop a proliposomal formulation to improve the oral bioavailability of valsartan. Proliposomes were formulated by thin film hydration technique using different ratios of phospholipids:drug:cholesterol. The prepared proliposomes were evaluated for vesicle size, encapsulation efficiency, morphological properties, in vitro drug release, in vitro permeability and in vivo pharmacokinetics. In vitro drug-release studies were performed in simulated gastric fluid (pH 1.2) and purified water using dialysis bag method. In vitro drug permeation was studied using parallel artificial membrane permeation assay (PAMPA), Caco-2 monolayer and everted rat intestinal perfusion techniques. In vivo pharmacokinetic studies were conducted in male Sprague Dawley (SD) rats. Among the proliposomal formulations, F-V was found to have the highest encapsulation efficiency of 95.6 ± 2.9% with a vesicle size of 364.1 ± 14.9 nm. The in vitro dissolution studies indicated an improved drug release from proliposomal formulation, F-V in comparison to pure drug suspension in both, purified water and pH 1.2 dissolution media after 12 h. Permeability across PAMPA, Caco-2 cell and everted rat intestinal perfusion studies were higher with F-V formulation as compared to pure drug. Following single oral administration of F-V formulation, a relative bioavailability of 202.36% was achieved as compared to pure valsartan.

Globally, in the last three decades of medical research, the use of liposomes as carrier for anti-HIV/AIDS drugs is gaining prominence. These potential anti-HIV nanocarriers are concentric lipid bilayers which can be fabricated to protect molecules and to target the drugs to specific sites, which is the reason behind their popularity in the antiretroviral drug delivery. The development of an effective drug delivery system such as liposomes presents an opportunity to circumvent the many challenges associated with antiretroviral drug therapy. The physiochemical properties of liposomes such as size, charge, and lipid composition significantly affect the liposomal efficiency. These nanocarriers offer advantages such as drug loading both in aqueous region and within the bilayer of the vesicles, act as solubilizing agents, protect drug from degradation in the body, allow modification of the pharmacokinetic and tissue distribution patterns of the drug, provide drug targeting, and have low immunogenicity, biocompatibility, and cell specificity. Different types of liposome-based delivery systems, such as cationic, anionic, sterically stabilized, and immunoliposomes, have been studied for the anti-HIV/AIDS drug delivery. Liposomes, however, face challenges with regard to their use in antiretroviral drug delivery such as limited hydrophilic drug-loading capacity, issues related to physical and biologic stability, poor scale-up, cost, short shelf life, and toxicity. Numerous patented strategies have been granted in the USA and around the world related to these anti-HIV nanocarriers. In the present article, we have discussed the general physiological aspects of the HIV infection, relevance of the nanocarrier, liposomes, in the treatment of this disease and some recently awarded US patents and patent applications of these liposomal delivery systems for anti-HIV drugs.

The objective of this study was to design an in situ biodegradable polymer implant controlled-release drug delivery system, using novel combinations of co-solvents and a model polypeptide, calcitonin (CT), and to assess the release of drug as a function of these co-solvents. Formulations were prepared by dissolving/ suspending CT polypeptide in poly-(lactic acid) (PLA) polymer solutions/suspensions containing combinations of a hydrophobic (benzyl benzoate, BB) and a hydrophilic (benzyl alcohol, BA) solvent. The CT-PLA mixtures were each injected into test tubes containing phosphate buffered saline solution to form the in situ implant and sampling was conducted over a 28-day period. The samples were analyzed for drug content using a modified Lowry protein assay procedure. Cumulative drug release demonstrated a rank-order correlation depending on the amount of the hydrophobic (BB) and hydrophilic (BA) solvents within each system. Increasing the amounts of the hydrophobic solvent, BB, in formulations demonstrated a 1.2-4.4-fold increase in CT release. Stability studies of all formulations over a 4-month period showed progressive increase in degradation of the CT polypeptide, especially at 37 degrees C, but a slower degradation pattern prevailed at 4 degrees and 20 degrees C. Differential scanning calorimetric studies revealed a homogenous mixture of drug in the polymer matrix. Overall, these studies demonstrated the feasibility of designing controlled release systems capable of releasing a polypeptide drug as a function of influence of different co-solvent combinations.

Purpose. To demonstrate the in vivo transdermal delivery and establish the comparative pharmacokinetics of five β-blockers in hairless rat.

In this study, we evaluated the ability of a coated, encapsulated formulation to increase the oral bioavailability of (±)-halofantrine (HF) enantiomers, a drug with low and erratic oral bioavailability. After encapsulation of HF in distearoylphosphatidylcholine, the dried particles were coated with cellulose acetate phthalate. A suspension of the product was made using methylcellulose as a dispersion agent, and the product was administered to Sprague-Dawley rats to provide a HF dose of 7 mg kg−1 as the HCl salt. HF HCl powder in 1 % methylcellulose with or without liposomal product excipients was also administered to separate groups of rats, which served as control groups. Serial blood samples were obtained from the rats and plasma was assayed by stereospecific high-performance liquid chromatography. There were no significant differences in the area under the concentration-time curve (AUC) or maximum concentration (Cmax) between the two control groups. Plasma concentrations of both HF enantiomers were significantly higher in the rats given HF as an encapsulated proliposomal formulation compared with the control groups. Compared with methyl-cellulose control, the encapsulation product resulted in increases of 41 to 47% in the AUC of HF enantiomers, and 90 to 100% in Cmax. The ability of an encapsulated proliposomal product to significantly increase the oral absorption of HF was clearly demonstrated.

Objective of the present study was to develop a proliposomal formulation to decrease the hepatic first-pass metabolism of a highly metabolized drug. Lovastatin was chosen as the model drug. Proliposomes were prepared by mixing different ratios of phospholipids such as soy phosphatidylcholine (SPC), hydrogenated egg phosphatidylcholine (HEPC) and dimyristoyl phosphatidylglycerol (DMPG) individually with drug and cholesterol in an organic solvent. Proliposomal powder was obtained following evaporation of the solvent. The proliposomal powder was either filled into capsules or compressed into tablets. Physical characterization, in vitro drug transport studies and in vitro dissolution of formulations and pure drug was carried out. In vitro transport across the membrane was evaluated using parallel artificial membrane permeability assay (PAMPA). The extent of drug released from various proliposomal formulations in the first 30 min was 85%, 87% and 96% with DMPG, SPC and HEPC containing formulations respectively, while the pure drug formulation showed 48% drug release in the same period. In vivo studies were carried out in male Sprague-Dawley rats. Following single oral administration of the selected formulation (F9), a relative bioavailability of 162% was achieved compared to pure lovastatin. The study demonstrated that proliposomes can be used as a drug delivery system to decrease the hepatic first-pass metabolism.

The objective of this study was to design lipid-based formulation to enhance the absorption of unmetabolized resveratrol (RSV) over adequate time and investigate various factors that contribute to prolonged absorption of RSV.Proliposomal formulations containing distearoyl phosphatidyl choline (DSPC) with or without cholesterol were prepared and evaluated. The liposomes obtained from hydration of proliposomal mixture were evaluated for size, zeta, physical appearance and entrapment. The integrity of liposomes in bile salt solution and solubility of RSV in sodium taurocholate solution in the presence of various concentrations of DSPC were evaluated to assess the stability and in varied gastrointestinal conditions. Finally, oral pharmacokinetic studies of liposomal dispersions in comparison with RSV solution were evaluated.Results revealed that spontaneous formation of liposomes did not occur upon hydration of RSV: DSPC proliposomes rather showed tendency to form loose cotton-like aggregates. Cholesterol aided in the formation of stable liposomes with large negative zeta potential. Release of RSV from liposomes in the presence of taurocholate was dependent on the amount and type of total lipid. Liposomes without cholesterol showed faster release, and release increased as the amount of DSPC in the formulation increased. Solubility studies indicated that DSPC increases the solubility of RSV in the presence of sodium taurocholate, and corroborates that bilayer assembly is disrupted because of interaction between RSV and DSPC. Mixture of RSV:DSPC:Chol at 1:0.25:0.25 formed stable colloidal dispersion with zeta potential -22 and released only 20 - 23% of entrapped RSV when incubated with 20 mM sodium taurocholate. Pharmacokinetic profile revealed that AUC and Cmax were twofold higher than plain RSV.The proliposomal formulation optimized by considering various physicochemical factors and simulated in vitro testing result in significant improvement rate and extent of absorption of unmetabolized RSV.

The purpose of this study was to improve the dissolution properties of a poorly water soluble and bioavailable drug, ethopropazine HCl (ET), by incorporating the drug in three different types of solid dispersion systems. Solid dispersions of ET were prepared using 1:1 (w/w) ratios of (1) phospholipid (1,2 dimyristoyl-sn-glycerophosphocholine) (DMPC), (2) polyethylene glycol 8000 (PEG8000), and (3) a novel combination of both DMPC and PEG8000. Using the solvent method of preparation, ET and DMPC and/or PEG were dissolved in chloroform, and solvent subsequently was evaporated using nitrogen gas. The resulting solid dispersion(s) was passed through a 60-mesh sieve. Characterization of ET/DMPC solid dispersion was performed by differential scanning calorimetry (DSC) and X-ray diffractometry studies. Dissolution studies conducted in phosphate buffered saline (PBS) (pH 7.4, 37 degrees C +/- 0.5 degrees C) using the USP type II (paddle) dissolution apparatus showed significant increases in the dissolution rate of ET with all the solid dispersions in this study. Specifically, within the first 5 min (D5), solid dispersions containing ET/DMPC (1:1) showed an eightfold increase in dissolution; in combination with DMPC and PEG8000 (1:1), there was an approximately sixfold increase; and a fourfold increase was observed with PEG8000 (1:1). Complete dissolution of all solid dispersions occurred within 60 min (D60) of the run. Storage of the ET/DMPC sample for over 4.5 months revealed a decrease in the dissolution rate when compared to freshly prepared sample. Overall, it was concluded that the dissolution rate of ET significantly improved when dispersed in all the selected carrier systems. However, the solid dispersion of ET/DMPC was observed to be superior to the other combinations used.

The objective of this study was to formulate a hydrogel-forming bioadhesive drug delivery system for oral administration of didanosine (ddI). The aim of this tablet dosage form is to improve the oral absorption of ddI by delivering it in small doses over an extended period and localizing it in the intestine by bioadhesion. Compressed tablets of ddI using Polyox WSRN-303, Carbopol 974P-NF, and Methocel K4M as the bioadhesive release rate-controlling polymers were prepared. The effect of polymer concentration on the release profile and in vitro bioadhesion of the matrix tablets was studied. Tablet formulations with Polyox WSRN-303 (10%) and Methocel K4M (30%) showed 93 and 90% drug release, respectively, after 12 h. The drug release was found to be linear when fitted in the Higuchi equation (square-root time equation), suggesting zero-order release. Carbopol 974-P-NF was found to inhibit the complete release of ddI because of drug-polymer interaction; hence, is not suitable for formulation of ddI. Drug diffusion and swelling of the polymer (anomalous Fickian release) was found dominant in ddI release. In general, in vitro bioadhesion increased with an increase in polymer concentration. Tablets containing a single polymer can be designed to form hydrogels serving the dual purpose of bioadhesion and sustained release.

A stability indicating high performance liquid chromatography method has been developed for simultaneous determination of acetaminophen, salicylamide and phenyltoloxamine. The reversed-phase method utilizes UV detection at 220 nm and a C8 column. This paper presents the data to support linearity, precision, specificity, and robustness of the method. The known potential degradation products of acetaminophen, p-aminophenol, p-nitrophenol, precursor impurity p-hydroxyacetophenone, the potential degradation product of salicylamide, salicylic acid, and precursor impurity ethylsalicylate were separated for quantitation simultaneous with parent compounds. Quantification was achieved by peak area and external standard method. This method can be employed in determining stability, assay, content uniformity, and dissolution of the combination in pharmaceutical dosage forms.

The objective of this study is to determine the effect of various neutral liposomes on corneal and conjunctival permeability of didanosine (ddI), an antiviral drug. Multi-lamellar vesicles (MLVs), large unilamellar vesicles (LUVs), and sonicated multi-lamellar vesicles (SMLVs) encapsulating ddI (with trace quantities of 3HddI) were prepared using distearoyl phosphatidylcholine (DSPC), a neutral lipid. The liposomes contained 14C-cholesteryl oleate as a lipid tracer. Liposome formulations containing free and encapsulated drug (f + e) and those containing only encapsulated drug (e) of an equal quantity were compared with free drug in this study. The permeability studies were conducted in the mucosal to serosal direction across excised rabbit cornea and conjunctiva. The percent encapsulation of ddI in MLVs, LUVs, and SMLVs was 25.66 0.30, 26.56 0.57, and 19.41 0.30, respectively. The mean particle size of MLVs, LUVs, and SMLVs containingfree and encapsulated drug was 3058, 774, and 270 nm, respectively. With...

The objective of this study was to examine the encapsulation of stavudine (d4T), an approved drug for AIDS treatment, in liposomes composed of various lipids and the in vitro release characteristics, and to evaluate the stability. The reverse phase evaporation method was used to prepare liposomes and the effect of cholesterol on drug encapsulation was studied by adding different amounts of cholesterol to a constant amount of lipid. The effect of charge of the lipid bilayer on drug encapsulation was also studied. Stearylamine or dicetylphosphate (10 mol%) were used to induce positive or negative charges, respectively. The particle size of the liposomes was measured using dynamiclightscattering. Stabilitystudies were performed by storing formulations at 4, 25, and 37 C for 12 weeks, and then subjecting them to alternate heat-cool cycles and simulated transportation conditions. Encapsulation of stavudine was found to be maximum (48%) in DSPC liposomes containing equimolar amounts of cholesterol. Encapsulatio...

Iontophoresis of colchicine solution through electroporated skin showed maximum enhancement as compared to iontophoresis and electroporation alone. Encapsulation of colchicine in positively charged liposomes further augmented the delivery,with the amount of drug in the receptor after 24 h being 1348 342 mug/cm2 when iontophoresis was performed through electroporated skin as compared to 666 38mug/cm2 when it was performed through nonelectroporated skin and 41 18mug/cm2 when only electroporation was performed. The impedance of the skin was observed to drop sharply due to electroporation, with a postpulse recovery of about 30% over 24h. Also the total amount transported was compared to the total charge delivered in the case of each of the protocols. Hence this serves as initial evidence for potential of charged liposomes for the enhanced transdermal delivery of nonionized or neutral drugs using a combination of electroporation and iontophoresis.

Phase equilibrium behavior of antibiotics is important in drug design and for optimization of the recovery process in manufacturing. Aqueous/organic partitioning behavior of a clinically important antibiotic, oxytetracycline is measured. The organic phase includes pure solvent n-hexane, chloroform, diethyl ether and ethyl acetate. In addition, measurements are also made for mixed organic phase composed of n-hexane+ethyl acetate. Organic-phase partitioning increases with the hydrogen bonding (H-bonding) tendency of the solvent in the order n-hexane

Phase equilibrium behaviour of antibiotics is important in drug design and for optimization of the recovery process in manufacturing. Aqueous/organic partitioning behaviour of a clinically important antibiotic, tetracycline is measured. The organic phase includes pure solvent n-hexane, chloroform, diethyl ether and ethyl acetate. Measurements are also made for mixed organic phase composed of n-hexane+ethyl acetate. Organic-phase partitioning increases with the hydrogen bonding tendency of the solvent in the order n-hexane

Phase equilibrium behavior of antibiotics is important in drug design and for optimization of the recovery processes in manufacturing. Antibiotics are high-cost fine chemicals, mostly manufactured by fermentation using inexpensive substrates. The major cost of manufacturing is involved in the separation processes. The aqueous/organic partitioning behavior of a clinically important antibiotic, chloramphenicol, is measured. The organic phase includes the pure solvents n-hexane, chloroform, diethyl ether, and ethyl acetate. In addition, measurements are also made for a mixed organic phase composed of n-hexane + ethyl acetate. Partitioning increases with the hydrogen bonding tendency of the solvent in the order n-hexane < chloroform < diethyl ether < ethyl acetate. Based on UNIQUAC and lattice-fluid hydrogen-bonding theories, an activity coefficient model (UNIQUAC-HB) is developed that includes hydrogen-bonding interaction. Single-solvent organic-phase data are correlated with the model, and free energy of hydrogen bonding parameters are obtained. Predictions made for mixed-solvent organic-phase systems agree well with the experimental data without using any adjustable parameter.

The pharmacokinetic profiles and tissue distribution, after single bolus intravenous doses of 2′,3′-dideoxyinosine (ddI) as a solution, a conventional liposomal formulation (without polyethylene glycol) of ddI and a long circulating liposomal formulation of ddI, were determined using rat as the animal model. Total ddI concentrations displayed multicompartment features following the conventional liposome preparation and appeared one compartment after the long circulating formulation. The ddI levels after the non liposomal preparation followed a one compartment model. The conventional liposomes showed a much greater volume of distribution compared to the long circulating liposomes and subsequently a longer t 1/2 . Due to the size of the conventional liposomes, these could not penetrate the fenestrated capillaries of the liver and thus had a lower accumulation in this tissue. Opsonization of these liposomes probably led to higher accumulation of the encapsulated ddI in the spleen, compared to when ddI was administered in a non liposomal form. The long circulating liposomes, on the other hand, provided a barrier to opsonin action and consequently had reduced accumulation in these tissues. The ddI levels in the pancreas were very low compared to the serum concentration after administration of the long circulating liposomes suggesting possible reduction of pancreatitis, an adverse effect of ddI.

Cytokine restraining agents (CRAs) are a family of compounds having profound anti-inflammatory properties. Among them, HP 228 is a heptapeptide, containing some unnatural amino acids, with the unique ability to restrain the pathological effects of cytokines without interfering with their essential immune functions. A liposomal formulation of HP 228 was developed to protect the drug from proteolytic enzymes and to provide controlled release of the drug. The liposomes were prepared using either dimyristoyl phosphatidylcholine or dipalmitoyl phosphatidylcholine and cholesterol by the thin-film hydration method. Dicetyl phosphate was added to the lipids to provide negative charge to the liposomes. Homogeneous size distribution of multilamellar vesicles (MLVs) was achieved by extruding them through the 800-nm polycarbonate membranes. The size distribution was characterized using a submicrometer particle size analyzer. Encapsulation efficiency of HP 228 was determined by adding protamine to MLVs and sep...

section 505(b)(2) 2 . The majority of those NDA’s under this section are new formulations. New dosage form, change of forms of drugs (Ester/salt), prodrug/active metabolite of drug and different route of administration are the few changes that the pharmaceutical companies are exploring for 505(b)(2) fillings 3 . The insoluble drugs are being reformulated. Hence this review summarises various solubilisation technologies and their commercial and health benefits. This review discusses drug formulations approved exploring different solubilisation technologies with insight to health benefits and commercial profits.

Glucosamine, as a dietary supplement for management of osteoarthritis, has a low and erratic oral bioavailability due to its transport-mediated absorption and presystemic loss in liver and GI tract. The present study described an effective approach to improve glucosamine intestinal absorption and hence its bioavailability using chitosan. Effects of chitosan on intestinal permeability and pharmacokinetics of glucosamine were evaluated in Caco-2 cell monolayer and rats, respectively. In addition, randomized crossover pharmacokinetic studies in beagle dogs were performed to evaluate the oral bioavailabilities of the developed glucosamine oral formulations containing chitosan (QD-Glu solution and QD-Glu tablet) in comparison to its commercial products. Caco-2 permeability studies demonstrated that chitosan could enhance the absorptive transport of glucosamine by 1.9-4.0-fold via the reversible opening of the cell tight junction. After oral administration of glucosamine solutions containing chitosan in rats, it was found that 0.5% (w/v) chitosan exhibited the highest enhancement in Cmax (2.8-fold) and AUC0-∞ (2.5-fold) of glucosamine. Further pharmacokinetic studies in beagle dogs demonstrated that QD-Glu solution and QD-Glu tablet showed much higher relative bioavailabilities of 313% and 186%, when comparing with Wellesse™ solution and Voltaflex™ tablet, respectively. In conclusion, chitosan could serve as a promising oral absorption enhancer for glucosamine.

2′,3′-Dideoxyinosine (ddI), an anti–human immunodeficiency virus (HIV) agent, was encapsulated in liposomes. The influence of the phospholipid/cholesterol ratio, concentration of phospholipid (PL), and chain length of PL on the encapsulation of ddI in multilamellar vesicles (MLVs), frozen and thawed multilamellar vesicles (FAT MLVs), and large unilamellar vesicles (LUVs) was studied. An optimum formulation was then selected to prepare long circulating liposomes. Stability studies at 4, 25, and 37°C and under certain stress conditions were performed. Release characteristics in phosphate buffer (pH 7.4) at 37°C were studied. Results show an increase in encapsulation efficiency (EE) with increasing amounts of cholesterol, a decrease in EE and increase in encapsulation yield (EY) with increasing concentrations of PL, and an increase in EE with increases in PL chain length, in both MLVs and LUVs. Freezing and thawing of MLVs had no influence on EE at a PL concentration of 10 mg/mL but increased EE at h...

Iontophoresis is useful for the transdermal delivery of charged drugs. However, nonionized drugs either have a low flux (due to electro-osmosis) or cannot be delivered using this technique. Because ionized or nonionized drugs can be encapsulated in charged liposomes, it was hypothesized that charged liposomes can deliver neutral or nonionized drug efficiently by iontophoresis. Colchicine, a neutral drug, was encapsulated in large unilamellar vesicles (LUVs), prepared with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) along with cholesterol (1:0.5 mole ratio). Multilamellar vesicles (MLVs) were prepared by the thin-film hydration method and LUVs were obtained by extruding MLVs through polycarbonate filters of 200 nm pore size. Positive charge was induced in the liposomes by adding stearylamine and negative charge by adding dicetyl phosphate. Nonencapsulated drug was separated from LUVs by...

Various drug delivery and targeting systems and approaches are currently utilized for cancer chemotherapy. Many drugs being developed through biotechnology are also in various stages of clinical trials. The most common approaches with drug delivery and targeting systems have been those using stealth liposomes or microspheres. Recent efforts have been made to use stealth nanoparticles for cancer drug delivery. In the next few years, it is expected that several liposomal products will be on the market. Another approach that has been utilized for some time has been the use of antibody-directed drugs or toxins. Several immunotoxins are currently in phase III trials, and efforts are being made to potentiate their activity with different potentiators. In an effort to understand the intricacies of tumor morphology and the limitations of drug targeting, various mathematical models have been proposed that help in designing appropriate delivery systems for successful tumor targeting. This review considers a...

Glyburide (GLY) is an oral hypoglycemic agent that is poorly soluble in water. The present study describes the preparation of solid dispersions and lyophilization of the dispersions designed to increase the solubility. Solid dispersions of GLY were prepared using polyethylene glycol 4000 (PEG 4000), PEG 6000 and a mixture of PEG 4000 and PEG 6000 (h1 mixture). The effect of melt and solvent methods of preparation of solid dispersion on dissolution behavior was also investigated. Dissolution studies indicated a significant increase in dissolution of GLY when dispersed in PEGs. Physical mixtures containing PEGs also showed improved dissolution of GLY as compared with that of pure drug, indicating the solubilizing effect of PEGs. Solid dispersions containing GLY/PEG 6000, 1:8, showed a 14-fold increase in dissolution after 60 min (D60) and another dispersion containing GLY/PEG 4000, 1:10, showed an 8-fold increase in the phosphate buffer system. The dispersion containing six parts of the PEG mixture (PEG 4000/PEG 6000, 1:1 mixture) showed a 12-fold increase in D60 as compared with pure drug. When multi-carrier solid dispersion containing six parts of mixture was prepared by the solvent method, the D60 value was about 2-fold that of the same dispersion prepared by the melt method. The dissolution of lyophilized solid dispersions further increased the dissolution of GLY significantly.

Liposomes have been used as carriers for drugs, toxins, enzymes, proteins/peptides and other bioactive materials there are several liposomal formulations that are being investigated in preclinical and clinical trials. Achieving high encapsulation as well as retention of the encapsulated drug is very important in developing liposomes as drug carriers. A high drug-to-lipid ratio is likely to reduce the cost of formulations and also the risk of lipid-induced toxicity following their injection. Comparison of the encapsulation efficiency of the drug in liposomes with the therapeutic dose indicates whether, in principle, liposomes can be used as a delivery system for that drug. The optimization of the liposomal encapsulation of a drug is usually based on trial and error, rather than on a thorough investigation of the factors affecting it. To obtain optimum encapsulation of a drug into a liposomal preparation, parameters influencing both the liposome and the drug need to be carefully considered during the early stages of development. In this review, factors that affect encapsulation of drugs in liposomes such as liposome size and type, charge on the liposome surface, bilayer rigidity, method of preparation, remote loading, addition of ion pairing, and complexing agents and characteristics of the drug to be encapsulated are discussed.

A promising strategy to improve the therapeutic efficiency of antimicrobial agents is targeted therapy. Although vancomycin has been considered a gold standard for the therapy of MRSA pneumonia, clinical failure rates have also been reported owing to its slow, time-dependent bactericidal activity, variable lung tissue penetration and poor intracellular penetration into macrophages. Liposomal encapsulation has been established as an alternative for antimicrobial delivery to infected tissue macrophages and offers enhanced pharmacodynamics, pharmacokinetics and decreased toxicity compared to standard preparations. The aim of the present work is to prepare vancomycin in two different liposomal formulations, conventional and PEGylated liposomes using different methods. The prepared formulations were optimized for their particle size, encapsulation efficiency and physical stability. The dehydration-rehydration was found to be the best preparation method. Both the conventional and PEGylated liposomal formulations were successfully formulated with a narrow particle size and size distribution and % encapsulation efficiency of and , respectively. Both the formulations were stable at C for 3 months. These formulations were successfully used to evaluate for their intracellular killing of MRSA and in vivo pharmacokinetic and bio-distribution studies.

rapid high-performance liquid chromatography (HPLC) method for the quantification of vancomycin in mouse plasma samples was developed and validated. Norvancomycin was used as the internal standard. Chromatographic separation was achieved on a Vydac C18 column (4.6×50 mm, 3 μm particle size) and the detection was made at 214 nm. A gradient elution was programmed with the mobile phases of 0.1% v/v trifluoroacetic acid (A) and 95:5 v/v acetonitrile: 0.1% TFA (B) and a flow rate of 1 ml/min. The total run time was 15 min. The calibration curve was linear over the range of 0.1-20 μg/ml, with a correlation coefficient (r) higher than 0.997 and the lower limit of quantitation (LLOQ) of 0.1 μg /ml. The intra-day accuracy values were between 90 and 112% and the inter-day ones ranged from 96 to 104%. Precision values ranged from 1.7 to 9.5% for intra-day and 6.3 to 9.4% for inter-day. Stability studies under normal laboratory conditions without significant loss of the drug. The assay was successfully applied to the pharmacokinetics and bio-distribution study of novel formulations of vancomycin in mice.

Liposomes bearing surface-attached antibody were prepared to study the retention of dideoxyinosine triphosphate (ddITP). Liposomes of various lipid composition were prepared and conjugated with modified mouse monoclonal antibodies. The antibody (H-2-K k ) used in this study is for Fc-mediated targeting. Antibody specificity was measured by studying the binding of antibody-liposome conjugates to antimouse IgG-Sepharose. The binding of antibody-liposome conjugates (L-Ab) was maximum when negatively charged liposomes (DMPC: CHOL: DCP) were employed. Inclusion of cholesterol to DMPC liposomes increased the binding by 4%. The binding was least when the neutral phospholipid compositions were employed (DMPC, DPPC and DMPC: CHOL) to prepare liposomes. The retention of ddITP was measured in plain liposomes and antibody-bearing liposomes stored at 4, 25 and 37°C. The leakage was maximal in DMPC liposomes. Only 20% of ddITP was retained in DMPC liposomes stored at 4°C after a month. However, when samples were stored at 25 and 37°C the retention was 12% and 4% respectively. There was no leakage of ddITP at 4 and 25°C in liposomes prepared using DMPC: CHOL (1:1 mole ratio) and DMPC: CHOL: DCP (7:2:1 mole ratio). The retention of ddITP was significantly increased in DMPC and DPPC liposomes after conjugation with antibodies. The retention of ddITP in DMPC: CHOL and DMPC: CHOL: DCP liposomes conjugated with antibodies was comparable to plain liposomes. These results suggest that the lipid composition used in the preparation of liposomes affect the conjugation of antibodies to liposomes and also the retention of an encapsulated drug.