[Preparation and intestinal absorption mechanism of self-assembled nanoparticles of Herpetospermum caudigerum].

In this experiment, the micro-precipitation method was used to prepare self-assembled nanoparticles of Herpetospermum caudigerum Wall.(MP-SAN). The process was optimized using average particle size and polydispersity index(PDI)as evaluation indexes. The mean particle size, PDI,zeta potential, and microstructure of MP-SAN were characterized. The intestinal absorption mechanism of dehydrodiconiferyl alcohol(DA)and herpetrione(Her)in MP-SAN was investigated through single-pass intestinal perfusion in rats. The optimized process parameters for producing MP-SAN were a stirring speed of 800 r·min~(-1),stirring time of 5 min, and rotary evaporation temperature of 40℃. The resulting MP-SAN exhibited a spherical-like structure and uniform morphology, with a mean particle size of(267.63±13.27) nm, a PDI of 0.062 0±0.043 9,and a zeta potential of(-46.18±3.66) mV. The absorption rate constant(K_a)and apparent permeability coefficient(P_(app))of DA in the ileal segment were significantly higher than those in the jejunal segment(P<0.05). However, there was no significant difference in the absorption of Her between the ileal and jejunal segments. Intestinal absorption parameters of DA and Her tended to increase with increasing drug concentration. Specifically, the K_a and P_(app) of DA in MP-SAN in the high-concentration group were significantly higher than those in the low-concentration group(P<0.01). The addition of verapamil, a P-glycoprotein inhibitor, did not significantly affect the intestinal absorption of DA and Her. However, the absorption of both DA and Her in MP-SAN was significantly increased by the addition of indomethacin(P<0.05),suggesting that DA and Her may be substrates for multidrug resistance-associated protein 2.

[Preparation and in vitro release of quercetin nanocrystals self-stabilized Pickering emulsion].

A new quercetin nanocrystals self-stabilized Pickering emulsion(QT-NSSPE) was prepared by high-pressure homogenization combined with probe ultrasonic method. The influences of oil fraction, quercetin(QT) concentration, and pH of water phase on the formation of QT-NSSPE were investigated. On this basis, the QT-NSSPE prepared under optimal conditions was evaluated in terms of microstructure, stability, and in vitro release and the droplet size and drug loading were 15.82 µm and 4.87 mg·mL~(-1), respectively. The shell structure formed by quercetin nanocrystals(QT-NC) on the emulsion droplet surface was observed under a scanning electron microscope(SEM). X-ray diffraction(XRD) showed that the crystallinity of adsorbed QT-NC decreased significantly as compared with the raw QT. There were not significant changes of QT-NSSPE properties after 30 days of storage at room temperature. The in vitro release experiment confirmed that QT-NSSPE has a higher accumulative release rate than the raw QT. All these results indicated that QT-NSSPE has a great stability and a satisfactory in vitro release behavior, which is a promising new oral delivery system for QT.

[Advances in formation and application of self-assembled nanoparticles from traditional Chinese medicine].

Due to the diverse sources and unique structures, the chemical components of Chinese medicinal materials are easy to self-assemble to form nanoparticles. The formation of self-assembled nanoparticles(SAN) can not only affect the absorption and distribution of the effective ingredients in Chinese medicinal materials but also may improve the biological activity of the effective ingredients or their simple mixtures, which is of great significance for revealing the compatibility mechanism of Chinese medicine prescription, developing new Chinese medicine products, and producing new nanomaterials. This paper reviews the formation, isolation, characterization, and application of SAN of Chinese medicines, and discusses the problems and development trends of the relevant research, which can provide reference for the further study and promote the innovation and application of such SAN.

[Effect of self-assembled nanoparticles from Shaoyao Gancao Decoction on release and absorption of main components of Baishao].

To study the effect of self-assembled nanoparticles from Shaoyao Gancao Decoction(SGD-SAN) on the encapsulation, in vitro release and intestinal absorption of the main components of Baishao. Particle size analysis and morphological observation were used to verify the formation of SGD-SAN in the decoction. The entrapment efficiency(EE) of SGD-SAN on the main components of Baishao was determined by ultrafiltration centrifugation. The dialysis bag method was used to study the in vitro release of the main components of Baishao with pH 6.8 phosphate buffer solution as the release media. Single-pass intestinal perfusion study was performed to investigate the effect of SGD-SAN on the absorption of the main components of Baishao. The results showed that there were nanoparticles in the SGD, and the particle sizes and PDI of SGD-SAN were about 200 nm and 0.38, respectively. SGD-SAN was irregularly spherical under transmission electron microscope(TEM). The EEs of albiflorin, paeoniflorin and benzoylpaeoniflorin in SGD-SAN were 33.78%±1.03%,33.61%±0.90%,88.53%±0.58%, respectively. The release characteristics of albiflorin, paeoniflorin and benzoylpaeoniflorin from SGD-SAN showed a slow-release effect on pH 6.8 phosphate buffer solution media. SGD-SAN could significantly enhance the absorption of albiflorin, paeoniflorin and benzoylpaeoniflorin in the ileum. The results of this study indicated that SAN could be formed during the mixed decoction of Baishao and Gancao, and SGD-SAN could encapsulate the components of Baishao, with a certain slow-release effect, and the formation of SAN facilitated the absorption of drugs in the ileum.

[Preparation and in vitro release of ginkgolide B nanosuspension].

To prepare ginkgolide B nanosuspension(GB-NS), and investigate its dissolution behaviors in vitro. The miniaturized media milling method was used to prepare nanosuspensions, with average particle size and polydispersity index as the evaluation indexes. The formulation and process of GB-NS were optimized by single factor experiment and Box-Behnken design-response surface method. The morphology was observed by scanning electron microscope(SEM), and thecrystallinity of GB-NS was investigated by X-rays diffraction(XRD). The paddle method was used to study the dissolution of GB-NS in vitro. The mean particle size of optimized GB-NS was(180±7) nm, with a polydispersity index of 0.196±0.036. SEM showed that GB-NS was rod-like or irregular granular. XRD showed that the crystallinity of GB-NS was significantly reduced compared with GB raw material. The cumulative dissolution rate of GB-NS reached 90% in 30 min, which was higher than that of GB raw material. The findings suggested that the miniaturized media milling method was simple, efficient and feasible to prepare GB-NS. And the dissolution rate of GB was significantly improved by nanosuspension technology.

[Preparation and in vitro quality evaluation of self-microemulsion co-loaded with tenuifolin and ß-asarone].

To prepare and optimize the self-microemulsion co-loaded with tenuifolin and ß-asarone(TF/ASA-SMEDDS) and evaluate its quality. The prescription compositions of TF/ASA-SMEDDS were screened by solubility test, single factor test and pseudo-tern-ary phase diagram, and the prescriptions were further optimized by Box-Behnken response surface method, with the drug loading and particle size as the evaluation indexes. Then the optimized TF/ASA-SMEDDS was evaluated for emulsified appearance, particle size, morphology and drug release in vitro. The optimized prescription for TF/ASA-SMEDDS was as follows: caprylic citrate triglyceride polyoxyethylene castor oil-glycerol(10.8∶39.2∶50), drug loading of(5.563±0.065) mg·g~(-1) for tenuifolin and(5.526±0.022) mg·g~(-1) for ß-asarone; uniform and transparent pan-blue nanoemulsion can be formed after emulsification, with particle size of(28.84±0.44) nm. TEM showed that TF/ASA-SMEDDS can form spherical droplets with a uniform particle size after emulsification; In vitro release test results showed that the drug release rate and cumulative release of tenuifolin and ß-asarone were significantly improved. The preparation process of TF/ASA-SMEDDS was simple and can effectively improve in vitro release of tenuifolin and ß-asarone.

[Study on preparation of volatile oil from Acorus tatarinowii self-nanoemulsion dropping pills and its protective effect on acute myocardial ischemia injury].

In this study, solid dispersion technology was used to develop volatile oil from Acorus tatarinowii self-nanoemulsion dropping pills(VOA-SNEDDS-DP) and its protective effect on acute myocardial ischemia injury was evaluated. Taking exterior quality, weight variation and the resolving time as comprehendsive evaluation indexes, the preparation process and formulation of the dropping pills were optimized by orthogonal design, and the dissolution rate in vitro of the optimized VOA-SNEDDS-DP was investigated. The rat model of acute myocardial ischemia was induced by intraperitoneal injection of isoproterenol hydrochloride and the serum levels of superoxide dismutase(SOD), malondialdehyde(MDA), creatine kinase(CK) and pathological changes of myocardial tissue were determined to evaluate therapeutic effect of the dropping pills on acute myocardial ischemia. The results showed that the optimal formulation and preparation process of VOA-SNEDDS-DP were as follows: PEG6000-PEG8000 was 1∶1, proportion of VOA-SNEDDS and matrix was l∶2.5, the temperature of drug fluids was 75 ℃, drop rate was 35 drops/min, drop distance was 5 cm, the condensing agent temperature was 2-10 ℃. The content of ß-asarone in the dropping pills was 42.46 mg·g~(-1). The accumulated dissolution rate of the dropping pills reached 93.85% in 10 min. The results of pharmacodynamic experiments showed that VOA-SNEDDS-DP could significantly increase the SOD content(P<0.05), reduce the levels of MDA and CK(P<0.05) in serum, and effectively improve the pathological morphology of myocardial tissue. These results revealed that the preparation of VOA-SNEDDS-DP by solid dispersion technology was stable and feasible, and VOA-SNEDDS-DP had protective effect on acute myocardial ischemia injury.

[Preparation and in vitro anti-hepatic fibrosis evaluation of herpetone nanosuspensions].

Herpetone( HPT) is a bioactive lignan extracted from Herpetospermum pedunculosum,which can protect liver,lower aminotransferase and inhibit hepatitis B virus. However,HPT has a poor oral bioavailability due to its poor water solubility. And there is no report about whether HPT has an anti-hepatic fibrosis activity. To improve the dissolution of HPT and study its anti-hepatic fibrosis activity and mechanism,the study group prepared herpetone nanosuspensions( HPT-NS) by the miniaturized media milling method. The formulation and process of HPT-NS were optimized by the single factor experiment. Scanning electron microscopy was used to observe morphology of HPT-NS. Dialysis method was used to study dissolution of HPT-NS in vitro. CCK8 method was used to assess the effect of HPT-NS on proliferation of the rat hepatic stellate cells( HSC-T6). Flow cytometry was used to assess the effect of HPT-NS on apoptosis and cell cycle of HSC-T6. The mean particle size of optimized HPT-NS was( 196±7) nm with a polydispersity index of 0.279±0.009.SEM showed that HPT-NS was in a regular rod shape. The cumulative dissolution rate of HPT-NS reached 93% in 18 h,and was higher than that of herpetone coarse suspensions( HPT-CS,28%). CCK8 experiment showed that the inhibition rate of HPT-NS on HSC-T6 was higher than that of HPT-CS. Flow cytometry showed that HPT-NS could block HSC-T6 cells in G2/M phase and induce apoptosis of HSC-T6 cells,with a significantly stronger effect than HPT-CS. The results revealed that HPT-NS significantly increased the in vitro dissolution of HPT,and enhanced the inhibitive effect on HSC-T6 cell proliferation by blocking cells in the G2/M phase and inducing late apoptosis.

[Preparation and quality evaluation of volatile oil from Acori Tatarinowii Rhizoma self-nanoemulsion].

In order to increase the solubility of volatile oil from Acori Tatarinowii Rhizoma, this study was to prepare self-nanoemulsion of volatile oil from Acori Tatarinowii Rhizoma . The prescriptions were preliminarily screened by miscibility studies, excipient compatibility tests, and pseudo-ternary phase diagrams, and then the optimal formulation was obtained by using the Box-Behnken response surface method, with particle size and drug-loading rate as the indicators. The self-nanoemulsion prepared by optimal prescription was characterized and evaluated for in vitro dissolution. The results showed that the optimal prescription for this volatile oil self-nanoemulsion was as follows: 41.7% volatile oil, 46.8% Tween-80, and 11.5% PEG-400. The prepared self-nanoemulsion was clear and transparent, with drug-loading of (192.77±1.64) mg·g⁻¹, particle diameter of (53.20±0.94) nm, polydispersity index of 0.230± 0.013, and Zeta potential of (-12.2±0.7) mV. The in vitro dissolution of self-nanoemulsion was higher than that of volatile oil. In this research, volatile oil served as the oil phase in self-nanoemulsion, so the prescription was simpler and the drug loading rate was higher. The prepared self-nanoemulsion complied with the relevant quality requirements, providing a reference for the preparation of volatile oil formulations.

[Research progress on in vitro and in vivo behaviors of poorly soluble Chinese materia medica nanosuspension].

Nanosuspension (also called nanocrystal suspension or nanocrystal) could significantly enhance the saturated solubility and dissolution of insoluble drugs, and improve their bioavailability by reducing particle size and increasing the specific surface, which could then solve the delivery problems of the poorly soluble active ingredients and effective parts of Chinese materia medica (CMM). Based on the brief summaries of nanosuspension preparation methods, this paper would mainly review the in vitro and in vivo behaviors of poorly soluble CMM nanosuspension, discuss and analyze its problems, so as to provide reference and thinking for the further study of nanosuspension drug delivery system of poorly soluble CMM and promote the development and perfection of nanosuspension technology in CMM.

[Preparation of astilbin amorphous nanosuspension and its in vitro evaluation].

Astilbil nanosuspension (AT-NS) was prepared by an antisolvent precipitation method. The formula and process of AT-NS were optimized by the single factor experiment. AT-NS was prepared under the optimal conditions, and its morphology and crystallinity were characterized. In vitro release of AT-NS was also determined. The particle size of AT-NS stabilized by PVP K30 was (149±3) nm, and the polydispersity index (PDI) and stability index (SI) were 0.137±0.014 and 0.940±0.012, respectively. The results of SEM showed that AT-NS was spherical. Both XRD and DSC showed that AT was amorphous in nanosuspension. In the in vitro release test, AT-NS showed a significantly increased dissolution. This simple low-cost approach could prepare AT-NS successfully. AT-NS could significantly improve the dissolution of AT and provide the reference to break the limitation on the clinical application of AT.

[Preparation of nanosuspension of quercetin with a miniaturized milling method].

The nanosuspension of quercetin (QT-NS) was prepared by a miniaturized milling method, and the process was optimized by Box-Behnken response surface method. Then the accumulative release rate of QT-NS in vitro was determined. The results showed that the optimal process parameters were as follows: ZrO2 4.5 mL, milling speed 690 r•min⁻¹ and milling time 1.5 h; the particle size of QT-NS was (169±5) nm, polydispersity index of 0.204±0.006 and stability index of 0.827±0.014, respectively. There was a little deviation between the theoretically predicted value and the measured value, indicating that this model had a good prediction effect. The accumulative release rate in vitro of QT-NS in 120 min was significantly higher than that of the raw drug and physical mixture. This simple low-cost miniaturization approach could prepare QT-NS successfully, and could provide reference for the formulation of the nanosuspension.

[Preparation of isopsoralen loaded nanostructured carrier and its in vitro transdermal permeation characteristics].

To increase the permeation and retention of isopsoralen in skin, and improve its bioavailability.Isopsoralen loaded nanostructure liquid carrier (IPRN-NLC) was prepared by high pressure homogenization andoptimized by orthogonal experiment with the encapsulation efficiency, drug loading and average particle size as the evaluation indexes. The in vitro transdermal permeation of IPRN-NLC was evaluated by Franze diffusion cells.The results showed that solid-liquid lipid ratio of optimum IPRN-NLC formulation was 7∶3,drug-lipid ratio of 1∶30, 1% surfactant. Under these conditions, IPRN-NLC had an average encapsulation of （90.25±0.73）%,drug loading of （1.56±0.27）% and an average particle size of (305±1.57) nm.The in vitro transdermal permeation results showed that IPRN-NLC could increase the amount of IPRN permeated though skin, with 3 times of the epidermal retention as compared with IPRN solution. From the results we can know that the IPRN-NLC prepared by high pressure homogenization can improve the permeation andaccumulation of IPRN in the skin, with wide application prospects in the field of transdermal administration.

Lignans-rich extract from Herpetospermum caudigerum alleviate physical fatigue in mice.

OBJECTIVE: To ascertain anti-fatigue constituents and mechanisms of Herpetospermum caudigerum. METHODS: The 80% ethanol extracts of Herpetospermum caudigerum were partitioned with chloroform, ethyl acetate and n-butanol, respectively. Male Kunming mice were divided into 13 groups with 16 mice in each group: a control group fed with water, 9 groups treated with 3 fractions of Herpetospermum caudigerum (chloroform fraction, ethyl acetate fraction and n-butanol fraction) at dose of 80, 160 and 320 mg/kg for the low-dose group, medium-dose group and high-dose group, 3 herpetrione (HPE) treated groups fed with HPE at dose of 15, 30, and 60 mg/kg for the low-dose group, medium-dose group and high-dose group. All animals were treated once per day for 30 days. Anti-fatigue activity was assessed through the forced swimming test and serum biochemical parameters including blood lactic acid (BLA), blood urea nitrogen (BUN), malondialdehyde (MDA), hepatic glycogen (HG), lactic dehydrogenase (LDH), superoxide dismutase (SOD) and glutathione peroxidase (GPx) determined following the recommended procedures provided by the commercial kits. RESULTS: Compared with the control group, the lignans extract (ethyl acetate fraction) of Herpetospermum caudigerum and HPE could signifificantly prolonged the exhaustive swimming time (P<0.05 or P<0.01), and also increased the HG levels (P<0.05 or P<0.01) and the activities of antioxidant enzymes (SOD, GPx and LDH, P<0.05 or P<0.01); BLA and MDA levels were decreased considerably in lignans extract and HPE treated groups (P<0.05 or P<0.01). HPE also could significantly decrease the BUN contents compared with the control group (P<0.05). The chloroform and n-butanol fraction showed no effect on swimming time and biochemical parameters. CONCLUSIONS: The lignans extract had antifatigue activities and HPE may be partly responsible for the anti-fatigue effects of Herpetospermum caudigerum. The possible mechanisms of anti-fatigue activity were related to the decrease of BUN and BLA, the increase of the HG storage and protecting corpuscular membrane by preventing lipid oxidation via modifying several enzyme activities.

Formulation of dried lignans nanosuspension with high redispersibility to enhance stability, dissolution, and oral bioavailability.

Herpetospermum caudigerum lignans (HTL), one of the potential drugs with anti-hepatitis B virus and hepatoprotective effects, has limited clinical applications because of poor aqueous solubility and low bioavailability. Both herpetrione (HPE) and herpetin (HPN) are the most abundant ingredients in HTL and exhibit weak acidity. The purpose of the present study was to produce dried preparations of HTL (composed of HPE and HPN) nanosuspensions (HTL-NS) with high redispersibility using lyophilization technology. The HTL-NS was prepared by utilizing precipitation-combined homogenization technology based on acid-base neutralization reactions, and critical formulation and process parameters affecting the characteristics of HTL-NS were optimized. The resultant products were characterized by particle size analysis, SEM, XRD, stability, solubility, dissolution and in vivo bioavailability. HTL-NS showed near-spherical-shaped morphology and the size was 243 nm with a narrow PDI value of 0.187. The dried preparations with a relatively large particle size of 286 nm and a PDI of 0.215 were achieved by using 4% (W/V) mannitol as cryoprotectants, and had a better stability at 4 or 25 °C for 2 months, compared to HTL-NS. In the in vitro test, the dried preparations showed markedly increased solubility and dissolution velocity. Besides, in the in vivo evaluation, it exhibited significant increases in AUC0-t, Cmax,MRT and a decrease in Tmax, compared to the raw drug. In conclusion, our results provide a basis for the development of a drug delivery system for poorly water-soluble ingredients with pH-dependent solubility.

Nanogel for dermal application of the triterpenoids isolated from Ganoderma lucidum (GLT) for frostbite treatment.

OBJECTIVE: The purpose of this study was to formulate stable Ganoderma lucidum (GLT) nanogels suitable for topical delivery with a view to improve the therapeutic effect for frostbite. METHODS: GLT nanosuspensions were formulated using the high-pressure homogenization technique and then suitably gelled for characterized. In order to confirm the advantages of GLT nanogel for dermal application, skin permeation studies in vitro and pharmacodynamic evaluation in vivo were studied and compared with GLT-carbopol gel. RESULTS: The particle size analysis and SEM studies revealed that GLT nanosuspensions were still stably kept their particle size after suitably gelled by carbopol preparation. The drug content, pH, and spreadability of the GLT nanogel was found to be 99.23 ± 1.8%, 6.07 ± 0.1, and 26.42 (g·cm)/s, which were within acceptable limits. In vitro permeation studies through rat skin indicated that the amount of GLT permeated through skin of GLT nanogel after 24 h was higher than GLT-carbopol gel, and GLT nanogel increased the accumulative amount of GLT in epidermis five times than GLT-carbopol gel. No oedema and erythema were observed after administration of GLT nanogel on the rabbits' skin. Pharmacodynamic study showed that GLT nanogel was more effective than GLT-carbopol gel in treatment of frostbite. CONCLUSION: The GLT nanogel possess superior therapeutic effect for frostbite compared with the GLT-carbopol gel, which indicates that nanogels are eligible for the use as a suitable nanomedicine for dermal delivery of poorly soluble drugs such as GLT.

[Analysis on intestinal absorption of paeoniflorin lipid liquid crystalline nanoparticles via everted intestinal sacs].

To study the absorption kinetics of paeoniflorin lipid liquid crystalline nanoparticles (Pae-LLCN) in different intestinal segments of rats and compare them with paeoniflorin(Pae) solution. Rat everted gut sac models were adopted for intestinal absorption test, and Pae content was determined by HPLC method to study the absorption characteristics of Pae-LLCN in rat duodenum, jejunum, ileum and colon, and investigate the effects of different drug concentrations on intestinal absorption. Results showed that Pae-LLCN and Pae were well absorbed at different intestine segments and different concentrations. The absorption constant Ka was increased with the increasing of the drug concentration, indicating possible passive absorption. The accumulative absorption volume Q and absorption constant Ka of Pae-LLCN were higher than those of Pae at each intestinal segment(P<0.05). The results revealed that Pae-LLCN and Pae could be well absorbed in whole intestinal segments and its mechanism may be passive absorption. LLCN can effectively improve the intestinal absorption of Pae.

[Rat intestine absorption kinetics study on cucurbitacin B-sodium deoxycholate/phospholipid mixed nanomicelles with in vitro everted gut sacs model].

To investigate the absorption kinetics of Cu B-SDC/PLC-MMs in rat different intestinal segments and compared with the absorption of Cu B suspension. The in vitro everted gut sacs model was established to study the absorption characteristics of Cu B-SDC/ PLC-MMs in rat duodenum, jejunum, ileum and colon, and the content of cucurbitacin B was detected by HPLC method, and the effects of concentrations on intestinal absorption were evaluated as well. The results showed that the absorption of Cu B-SDC/PLC-MMs was linearity at different intestine segment and different concentrations (R2 > 0.9), which was consistent with zero order rate process. The Ka of different intestine segments showed a concentration-dependent increasing along with the raised concentration of Cu B-SDC/ PLC-MMs, indicating that it was likely to be a mechanism of passive absorption. The best absorption site of Cu B-SDC/PLC-MMs was ileum, and its absorptions in different intestinal segments were superior to cucurbitacin B suspension. SDC/PLC-MMs could significantly enhance the intestinal absorption of cucurbitacin B, and the study of intestinal absorption kinetics of Cu B-SDC/PLC-MMs had gave a support to its further reasonable solidfication.

Nanostructured lipid carrier based topical gel of Ganoderma Triterpenoids for frostbite treatment.

The objective of this study was to prepare nanostructured lipid carrier (NLC)-based topical gel of Ganoderma Triterpenoids (GTs) and evaluate their effects on frostbite treatment. GT-NLCs was prepared by the high pressure homogenization method and then characterized by morphology and analyses of particle size, zeta potential, entrapment efficiency (EE), and drug loading (DL). The NLCs was suitably gelled for skin permeation studies in vitro and pharmacodynamic evaluation in vivo, compared with the GT emulgel. The GT-NLC remained within the colloidal range and was uniformly dispersed after suitably gelled by carbopol preparation. Transmission electron microscopy (TEM) study showed GT-NLCs was spherical in shape. The EE (%) and DL (%) could reach up to (81.84 ± 0.60)% and (2.13 ± 0.12)%, respectively. The result of X-ray diffractograms (XRD) showed that GTs were in an amorphous state in the NLC-gel. In vitro permeation studies through rat skin indicated that the amount of GTs permeated through skin of GT-NLCs after 24 h was higher than that of GT emulsion, and GT-NLCs increased the accumulative amounts of GTs in epidermis 7.76 times greater than GT emulsion. GT-NLC-gel was found to possess superior therapeutic effect for frostbite, compared with the GT emulgel. The NLC based topical gel of GTs could improve -their therapeutic effect for frostbite.

Influence of drug physicochemical characteristics on in vitro transdermal absorption of hydrophobic drug nanosuspensions.

The purpose of this paper was to study the influence of drug physicochemical characteristics on in vitro transdermal absorption of hydrophobic drug nanosuspensions. Four drug nanosuspensions were produced by high-pressure homogenization technique, which were the same in stabilizer and similar in particle size. Differential scanning calorimetry and powder X-ray diffraction analysis showed that the crystalline state of the nanocrystals did not change. In vitro permeation study demonstrated that the drug nanosuspensions have a higher rate of permeation that ranged from 1.69- to 3.74-fold compared to drug microsuspensions. Correlation analysis between drug physicochemical properties and Jss revealed that log P and pKa were factors that influenced the in vitro transdermal absorption of hydrophobic drug nanosuspensions, and drugs with a log P value around 3 and a higher pKa value (when pKa < pH+2) would gain higher Jss in this paper.