Fengying Sun

Design of a long-term antipsychotic in situ forming implant and its release control method and mechanism

Two kinds of in situ forming implants (ISFIs) of atypical antipsychotics, risperidone and its 9-hydroxy active metabolite, paliperidone, using poly(lactide-co-glycolide)(PLGA) as carrier, were investigated. Significant difference was observed in the solution-gel transition mechanism of the two systems: homogeneous system of N-methyl-2-pyrrolidone (NMP) ISFI, in which drug was dissolved, and heterogeneous system of dimethyl sulfoxide (DMSO) ISFI, in which drug was dispersed. Fast solvent extractions were found in both systems, but in comparison with the high drug release rate from homogeneous system of drug/polymer/NMP, a fast solvent extraction from the heterogeneous system of drug/polymer/DMSO was not accompanied by a high drug release rate but a rapid solidification of the implant, which resulted in a high drug retention, well-controlled initial burst and slow release of the drug. In vivo study on beagle dogs showed a more than 3-week sustained release with limited initial burst. Pharmacologic evaluation on optimized paliperidone ISFIs presented a sustained-suppressing effect from 1 day to 38 day on the MK-801 induced schizophrenic behavior mice model. A long sustained-release antipsychotic ISFI of 50% drug loading and controlled burst release was achieved, which indicated a good potential in clinic application.

Studies on the preparation, characterization and pharmacological evaluation of tolterodine PLGA microspheres.

In this study, poly(d,l-lactide-co-glycolide) (PLGA) microspheres of tolterodine depot formulation were prepared using oil in water (o/w) method to investigate their potential pharmacokinetic and pharmacodynamic advantages over tolterodine l-tartrate tablets. Morphological studies of the microspheres showed a spherical shape and smooth surface with mean size of 50.69-83.01 microm, and the encapsulation efficiency was improved from 62.55 to 79.10% when the polymer concentration increased from 180 to 230 mg/ml. The addition of stearic or palmitic acids could significantly raise the drug entrapment efficiency but only slightly affected the in vitro release. A low initial burst followed by a proximately constant release of tolterodine was noticed in the in vitro release profiles. The in vivo study was carried out by intramuscular (i.m.) administration of tolterodine-loaded microspheres on beagle dogs, and a sustained release of drug from the PLGA microspheres was achieved until the 18th day with a low initial burst. Since the absence of hepatic first pass metabolism, only a single active compound-tolterodine was detected in the plasma. This avoided the coexistence of two active compounds in plasma in the case of oral administration of tolterodine, which may lead to a difficulty in dose control due to the different metabolic capacity of patients. In the pharmacodynamic study, the influence of tolterodine PLGA microspheres on the inhibition of carbachol-induced rat urinary bladder contraction was more significant than that of tolterodine l-tartrate tablets. There were invisible changes in rat bladder slices between tolterodine-loaded PLGA microspheres group and tolterodine l-tartrate tablets group. These results indicate that the continuous inhibition of muscarinic receptor may offer an alternative therapy of urge incontinence.

The glucose-lowering potential of exenatide delivered orally via goblet cell-targeting nanoparticles.

PurposeExenatide, a potent insulinotropic agent, can be used for the treatment of non-insulin-dependent diabetes mellitus. However, the need for frequent injections seriously limits its therapeutic utility. The aim of present report was to develop an orally available exenatide formulation using goblet cell-targeting nanoparticles (NPs).MethodThe exenatide-loaded nanoparticles were prepared with modified chitosan which was conjugated with a goblet cell-target peptide, CSKSSDYQC (CSK) peptide.ResultsThe CSK-chitosan nanoparticles shown reduced chitosan toxicity and enhanced the permeation of drugs across the Caco-2/HT-29 co-cultured cell monolayer, which simulated the intestinal epithelium. Following the oral administration of near-infrared fluorescent probe Cy-7-loaded NPs to mice, the distribution of the drugs was investigated with a near-infrared in vivo image system (FX Pro, Bruker, USA). The results showed that Cy-7 fluorescence disseminated from the oesophagus, then to stomach and small intestine and then was absorbed into hepatic, finally into the bladder; over time, Cy-7 was metabolized and excreted. The bioavailability of the modified nanoparticles was found to be 1.7-fold higher compared with the unmodified ones, and the hypoglycemic effect was also better.ConclusionCSK peptide-modified chitosan nanoparticles could be a potential therapeutics for Type II diabetes patients.

Parenteral thermo-sensitive organogel for schizophrenia therapy, in vitro and in vivo evaluation.

Novel biodegradable in situ forming organogel, obtained via the self-assembly of long chain fatty acid in pharmaceutical oil, was prepared and characterized. Different from traditional organogels, the use of organic solvent was avoided in this gel system, in consideration of its tissue irritation. Four kinds of fatty acids were employed as organogelators, which could successfully gel with injectable soybean oil. The gelation procedure was thermo-reversible. Phase transition temperature and time were depended on carbon chain length and concentration of gelators. Optimized formulations containing drug were then injected subcutaneously in rats for pharmacokinetic study. Results showed the steady drug release for one week with the well-controlled burst, which fitted well with the drug release mechanism of both drug diffusion and frame erosion. In vivo imaging of the organogel with fluorescence in live animals suggested that the organogel matrix was gradually absorbed and completely up-taken in nine days. Histopathological analysis of the surrounding tissues was carried out and revealed an overall good biocompatibility property of the implants over drug release period. This research demonstrates that this thermo-sensitive in situ forming organogel system represents a potentially promising platform for sustained drug delivery.

Role of Four Different Kinds of Polyethylenimines (PEIs) in Preparation of Polymeric Lipid Nanoparticles and Their Anticancer Activity Study.

A series of polyethylenimines-coated poly(d,l-lactide-co-glycolide)/lipid nanoparticles (PPLs) were fabricated for delivering paclitaxel via a simple nano-precipitation method. Four kinds of polyethylenimines (PEIs) (800 Da-, 2000 Da- and 25 kDa-branched PEIs, and 25 kDa-linear PEI) were selected as a polymeric coating for the nanoparticles. The PPLs were evaluated for their cytotoxic effects towards tumor cells. The nanoparticles were uniform spheres with particle sizes ranging from 135.8 to 535.9 nm and zeta potentials between 13.5 and 45.4 mV. The content of lipids and PEIs were optimized at lipids content from 0 to 40% and PEI content from 2.5% to 10%, respectively. At 20% lipid content and 5% PEI content, the formulation was found to be optimal. In vitro experiments showed that 25 kDa-branched PEI coated PLGA/lipid nanoparticles (25k-bPPLs) had higher cytotoxicity than other PPLs in several cancer cell lines. Meanwhile, 25k-bPPLs maintained high cellular delivery efficiency without excessive toxicity, which was confirmed by confocal microscopy and flow cytometry analyses. Furthermore, 25k-bPPLs displayed excellent colloidal stability in pH 7.4 PBS. In conclusion, 25k-bPPLs are promising drug delivery vehicles for cancer therapeutics.

Design of hydrogels of 5-hydroxymethyl tolterodine and their studies on pharmacokinetics, pharmacodynamics and transdermal mechanism

&NA; development, single‐factor experiments were employed to evaluate the effect of adding different matrix, enhancers, 5‐HMT, ethanol and glycerol on drug skin development, single‐factor experiments were employed to evaluate the effect of adding different matrix, enhancers, 5‐HMT, ethanol and glycerol on drug skin permeation. Finally, Carbopol 940 was selected as the gel matrix with N‐methyl pyrrolidone (NMP) chosen as the enhancer. The relationship between time and the steady accumulative percutaneous amount (Q, &mgr;g cm−2) of optimized 5‐HMT hydrogels was Q4–12 h = 1290.8 t1/2 − 1227.7. The absolute bioavailability of 5‐HMT hydrogels was 20.7% showed in pharmacokinetic study. No skin irritation was observed in 5‐HMT hydrogels skin irritation study. In the pharmacodynamic study, the overactive bladder model was induced by 150 &mgr;g/kg of pilocarpine in rats. The significant effects of 5‐HMT hydrogels on the inhibition of urine output on rat model were last to 12 h. The optimized 5‐HMT hydrogels displayed prolonged pharmacological responses. 5‐HMT hydrogels effectively avoided the metabolism difference of enzyme in bodies compared with tolterodine tablets, provided one single active compound in plasma to reduce the variability of having two active compounds. To further elucidate the transdermal mechanism, fourier transform infrared (FTIR) spectroscopy, differential scanning calorimeter (DSC) and activation energy measurements were used to study the transdermal routes and changes of stratum corneum during drug release. Graphical Abstract Figure. No caption available.

Preparation, characterization and pharmacological evaluation of tolterodine hydrogels for the treatment of overactive bladder.

In this study, transdermal gel formulations for tolterodine were developed to investigate the effects of gel matrix and chemical enhancers on drug skin permeation from tolterodine hydrogels. In vitro permeation studies of tolterodine through excised mouse skin were carried out using Franz-type diffusion cells. In the optimum gel formulation, Carbopol 940 was selected as the gel matrix. Compared to gels without enhancer, tolterodine hydrogels with N-methyl pyrrolidone (NMP) showed significant enhancing effect on transdermal permeation of tolterodine (p<0.05). The results of in vitro percutaneous delivery experiment showed that the relationship of the steady accumulative percutaneous amount (Q, μg cm(-2)) of tolterodine hydrogels and time was Q4-12h=770.19t(1/2)-966.99. Tolterodine permeated at the steady-state speed of 770.19 μg cm(-2)h(-1) and its release coincided with Higuchi Equation. The pharmacokinetic properties of the optimized tolterodine formulation were studied in rabbits. The absolute bioavailability of tolterodine was 11.47%. Since the absence of hepatic first-pass metabolism, only a single active compound-tolterodine was detected in the plasma. A skin irritation study was also carried out on rabbits, and the results showed tolterodine hydrogels had no skin irritation. In the pharmacodynamic study, the significant effects of tolterodine hydrogels on the inhibition of pilocarpine-induced rat urinary bladder contraction were last to 12h, indicating that tolterodine hydrogels could produce prolonged pharmacological responses. In conclusion, tolterodine hydrogels were formulated successfully using Carbopol 940 and NMP and these results helped in finding the optimum formulation for percutaneous drug release. It is quite evident that tolterodine hydrogels may offer a possibility to avoid the first-pass effect, resulting in a single active compound of tolterodine in plasma, which may profit on the patient under the dose control and the reduction of potential adverse effect from two active compounds in the body.

Multifunctional folate receptor-targeting and pH-responsive nanocarriers loaded with methotrexate for treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by progressive cartilage and bone destruction. Activated macrophages that overexpress folic acid (FA) receptors play an important role in RA, due to their abundance in inflamed synovial membrane and joints. In an effort to deliver drugs to the inflamed tissues, multifunctional FA receptor-targeting and pH-responsive nanocarriers were developed. They were composed of lipids, polyethylene glycol (PEG)–poly(lactic-co-glycolic acid) (PLGA) forming a hydrophilic shell, FA around the hydrophilic shell as a targeting ligand, and poly(cyclohexane-1,4-diylacetone dimethylene ketal) (PCADK) and PLGA as a hydrophobic core. PCADK also acts as a pH-responsive material. Methotrexate (Mtx) was encapsulated in the nanoparticles, which exhibited pH-responsive release in vitro. Cellular uptake and cytotoxicity experiments revealed that FA-PEG-PLGA/PCADK–lipid nanoparticles loaded with Mtx (FA-PPLNPs) exhibited superior cellular uptake and higher cytotoxicity to activated macrophages than PPLNPs/Mtx. The therapeutic effect of FA-PPLNPs/Mtx in RA was confirmed in an adjuvant-induced arthritis rat model. These results suggest that the multifunctional folate receptor-targeting and pH-responsive nanocarriers are promising for the treatment of RA.

The Effects of LPM570065, a Novel Triple Reuptake Inhibitor, on Extracellular Serotonin, Dopamine and Norepinephrine Levels in Rats

Triple reuptake inhibitors (TRIs) are currently being developed as a new class of promising antidepressants that block serotonin (5-HT), dopamine (DA) and norepinephrine (NE) transporters, thereby increasing extracellular monoamine concentrations. The purpose of this study was to investigate the effects of LPM570065, a novel TRI and a desvenlafaxine prodrug, on extracellular 5-HT, DA and NE levels in the rat striatum after acute and chronic administration relative to desvenlafaxine, using High Performance Liquid Chromatography (HPLC) and microdialysis. Acute administration was performed by providing rodents with oral solutions (0.06 mmol·kg−1 p.o.), oral suspensions (0.06 mmol·kg−1 p.o.) and intravenous solutions (0.04 mmol·kg−1 i.v.) of LPM570065 and desvenlafaxine. Oral suspensions (0.06 mmol·kg−1·day−1) of the two drugs were also administered for a 14-day chronic period. HPLC analysis revealed that LPM570065 rapidly penetrated the rat striatum, converted into desvenlafaxine and exhibited larger total exposure compared with the administration of desvenlafaxine. Microdialysis revealed that acute and chronic administration of oral suspension of LPM570065 increased the 5-HT, DA and NE levels more than the relative administration of desvenlafaxine. Unlike desvenlafaxine, acute administration of an intravenous LPM570065 solution did not induce the undesirable 90% decrease in extracellular 5-HT levels. In contrast to the fully dose-dependent elevation of 5-HT induced by desvenlafaxine, the acute administration of LPM570065 showed a capped increase in extracellular 5-HT levels when combined with WAY-100635. Additionally, forced swim test demonstrated that acute and chronic administration of LPM570065 reduced the immobility time more than the relative administration of desvenlafaxine. These data suggest that LPM570065 may have greater efficacy and/or a more rapid onset of antidepressant action than desvenlafaxine and also counterbalance the harmful effects of desvenlafaxine on 5-HT neurotransmission related to 5-HT1A autoreceptors. Thus, this new class of drugs, TRIs has the potential to provide a new therapeutic mechanism for treating depression.

Design of transparent film-forming hydrogels of tolterodine and their effects on stratum corneum

A transparent film-forming hydrogel formulation for tolterodine was developed using ternary phase diagram and Box-Behnken design (BBD). Carbopol 980 (neutralized by triethanolamine), hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC) and Tween 80 were used as matrices. Solvent was the mixture of water and ethyl alcohol. The measured 24 h cumulative drug release rate (86.02%) was consistent with the predicted value (85.42%) in mice. Steady-state flux (J) of tolterodine in optimized formulation across rat full skin, epidermal, dermis and subcutaneous tissue were 15.83, 18.55, 37.15 and 81.82 μg cm(-2) h(-1), respectively. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results suggested that the hydrogels could impact lipid status in SC, which was consistent with Ea (8.638 kcal/mol) of tolterodine from optimized formulation in rats. In the pharmacokinetic studies, sustained-release over 24 h and absolute bioavailability of the hydrogels (24.53%) was higher than tolterodine tablets (15.16%) in rats. The hydrogels were suitable for systemic administration of tolterodine for the treatment of overactive bladder.