Dissolving Microneedles as Skin Allergy Test Device.

The possibility of using dissolving microneedles (DMs) as a skin allergy test device was studied in rats. Poly-L-arginine was used as a model allergen. Dextran was used to prepare three kinds of DM array chips containing different doses of poly-L-arginine: 17.1±0.5 µg (low-dose DM), 42.2±0.8 µg (medium-dose DM), and 87.4±1.1 µg (high-dose DM); each 1.0 cm2 chip contained 300 DMs. The mean lengths of the low-, medium-, and high-dose DM were 489±3, 485±3, and 492±1 µm and mean diameters of the base were 301±2, 299±1, and 299±2 µm, respectively. Furthermore, for the low-, medium-, and high-dose DM, the administered doses of poly-L-arginine were estimated to be 9.3±1.9, 31.1±1.3, and 61.9±4.7 µg and the scratching behavior per 30 min was 9.8±3.4, 60.4±8.3, and 95.7±10.6 times, respectively. These results demonstrate the dose dependence of the immunoreactivity of the poly-L-arginine DMs, suggesting that DMs can be used an alternative skin allergy device.

Dissolving microneedles for enhanced local delivery of capsaicin to rat skin tissue.

Capsaicin-loaded dissolving microneedles (DMNs) were prepared to investigate the analgesic effect of capsaicin on the skin. The dimensions of each microneedle (MN) were as follows: diameter of the basement, 17 mm; length, 500 µm; and width, 300 µm. The average capsaicin content in the DMNs loaded with a low and high dose of capsaicin was 8.8 ± 0.5 mg and 12.5 ± 0.4 mg. Almost all the capsaicin, 99.3 ± 4.1% and 99.7 ± 2.2% for low-dose and high-dose DMNs were released within 20 min. High amounts of capsaicin were recovered with 102.8 ± 0.1% of capsaicin after storage at 23 °C for 90 days. The pharmacological activity of capsaicin DMNs was compared to that of capsaicin cream as a positive control, by measuring the idiospasm of depilated rat skin. The time required to achieve 50% idiospasm suppression was 26.3 ± 1.9 min and 53.0 ± 2.3 min for low-dose and high-dose DMNs. A pharmacokinetic study showed high tissue capsaicin levels of 660.2 ± 120.6 and 1805.3 ± 218.1 µg/g wet weight for low-dose and high-dose DMNs at 5 min after administration. The results suggest that DMNs could exert a rapid local analgesic action on the skin.

Transport of Azithromycin into Extravascular Space in Rats.

Recent clinical trials showed a prolonged retention of subinhibitory concentrations of unbound azithromycin in the interstitial fluid of soft tissues despite the fact that azithromycin is extensively distributed in tissues. In these clinical trials, interstitial fluid samples were obtained by using the microdialysis method, and it was established that drug concentrations represent protein-unbound drug concentrations. The present study was designed to measure total azithromycin concentrations in the interstitial fluid of the skin of rats by directly collecting interstitial fluid samples from a pore formed on the skin by a dissolving microneedle array. The total azithromycin concentrations in interstitial fluid of the skin were about 4 to 5 times higher than those in plasma throughout the experimental period, and stasis of the azithromycin concentration in interstitial fluid was observed when the concentration of azithromycin in plasma was at the lower limit of quantification. In addition, the skin/plasma concentration ratio transiently increased after dosing (from 4.3 to 83.1). Our results suggest that azithromycin was trapped inside white blood cells and/or phagocytic cells in not only blood but also interstitial fluid, resulting in a high total azithromycin concentration and the retention of its antimicrobial activity at the primary infection site. The stasis of azithromycin in interstitial fluid and skin would lead to long-lasting pharmacological effects (including those against skin infection) at concentrations exceeding the MIC.

Therapeutic Drug Monitoring of Vancomycin in Dermal Interstitial Fluid Using Dissolving Microneedles.

OBJECTIVE: To design an alternative painless method for vancomycin (VCM) monitoring by withdrawing interstitial fluid (ISF) the skin using dissolving microneedles (DMNs) and possibly replace the conventional clinical blood sampling method. METHODS: Male Wistar rats were anesthetized with 50 mg/kg sodium pentobarbital. Vancomycin at 5 mg/mL in saline was intravenously administered via the jugular vein. ISF was collected from a formed pore at 15, 30, 45, 60, 75, 90, and 120 min after the DMNs was removed from the skin. In addition, 0.3 mL blood samples were collected from the left femoral vein. RESULTS: The correlation between the plasma and ISF VCM concentrations was significantly strong (r = 0.676, p < 0.05). Microscopic observation of the skin after application of the DMNs demonstrated their safety as a device for sampling ISF. CONCLUSION: A novel monitoring method for VCM was developed to painlessly determine concentrations in the ISF as opposed to blood sampling.

Semi-physiological pharmacokinetic-pharmacodynamic (PK-PD) modeling and simulation of 5-fluorouracil for thrombocytopenia in rats.

1. The aim of this study was to develop a simple pharmacokinetic-pharmacodynamic (PK-PD) model that could characterize the complete time-course of alterations in platelet counts to predict the onset and degree of thrombocytopenia, which severely limits the use of the anticancer agent 5-fluorouracil (5-FU), in rats. 2. Platelet counts were measured in rats following the intravenous administration of various doses of 5-FU for 4 days to obtain data for an analysis of the PK-PD model. Our PK-PD model consisted of a two-compartment PK model, with three compartments for the PD model and 10 structural PK-PD model parameters. 3. After the 5-FU treatment, platelet counts transiently decreased to a nadir level, showed a rebound to above the baseline level before recovering to baseline levels. Nadir platelet counts and rebounds varied with the AUC0-∞ level. The final PK-PD model effectively characterized platelet count data and final PD parameters were estimated with high certainty. 4. This PK-PD model and simulation may represent a valuable tool for quantifying and predicting the complete time-course of alterations in blood cell counts, and could contribute to the development of therapeutic strategies with 5-FU and assessments of various novel anticancer agents that are difficult to examine in humans.

Application of dissolving microneedles to glucose monitoring through dermal interstitial fluid.

Dissolving microneedles (DMs) were applied to glucose monitoring in the dermal interstitial fluid (ISF) of rats and their potential as an alternative blood glucose monitoring device was evaluated. Sodium chondroitin sulfate was used to prepare DM array chips, which consisted of 300 DMs/cm(2). The mean length of the DMs was 475±18 µm and the mean diameter of the basement was 278±8 µm. After DMs were inserted into the skin of the hair-removed rat abdomen, a wet unwoven cloth containing 10-30 µL of water was placed on the skin and ISF was extracted. By increasing the absorbed amount of water on the unwoven cloth from 10 to 30 µL, the extracted amount of glucose increased from 1.66±0.35 µg to 2.75±0.61 µg. Increasing the adhesion time of the wet unwoven cloth to the skin from 0.1 to 5.0 min, increased the amount of ISF glucose from 1.99±0.13 µg to 5.04±0.38 µg. The relation between the amount of glucose in ISF and blood glucose concentrations was examined. With increase in the adhesion time, the coefficient of determination, r(2), increased from 0.501 to 0.750. The number of DMs also affected the relationship and values of the coefficient of determinations, r(2) were: 0.340 (25 DMs), 0.758 (50 DMs), 0.763 (100 DMs), 0.774 (200 DMs), and 0.762 (300 DMs). These results indicate the usefulness of DMs as an alternative blood glucose monitoring device.

Pharmacokinetic-pharmacodynamic (PK-PD) modeling and simulation of 5-fluorouracil for erythropenia in rats.

INTRODUCTION: The aim of the present study was to develop a simple pharmacokinetic-pharmacodynamic (PK-PD) model in rats that could predict the onset and degree of erythropenia, a severely toxic side effect that severely limits the use of the anticancer agent 5-fluorouracil (5-FU). METHODS: Total erythrocyte counts, hemoglobin (Hb) concentrations, and hematocrit (Hct) levels were measured in rats following the intravenous bolus administration of 5-FU for 4 days in order to obtain data for an analysis of the PK-PD model. Our PK-PD model consisted of a two-compartment PK model, with two compartments for the PD model and nine structural PK-PD model parameters. RESULTS: After the intravenous bolus administration of 5, 10, or 20 mg/kg of 5-FU to rats, absolute erythrocyte counts, Hb concentrations, and Hct levels transiently decreased, reached minimum levels on Days 7-14, and then returned to baseline levels. The nadir values (Cnadir) for rats treated with 5, 10, or 20 mg/kg of 5-FU were significantly decreased to approximately 79.4, 76.3, or 46.5% of the baseline value (Cbaseline) in erythrocyte counts, 86.3, 83.3, or 45.7% of Cbaseline in Hb concentrations, 88.6, 85.5, or 47.1% of Cbaseline in Hct levels, respectively. The PK-PD model effectively captured the features of erythropenia and Cnadir after 5-FU chemotherapy. This PK-PD model was successfully used to characterize the learner relationship between the area under the plasma 5-FU concentration-time curve (AUC0-∞) following the intravenous bolus administration of 5-FU and the Cnadir in erythrocyte counts, Hb concentrations, and Hct levels after the 5-FU treatment. DISCUSSION: The results of the present study suggest that the administration of a pharmacokinetically modified dose of 5-FU could minimize the Cnadir in erythrocyte counts, Hb concentrations, and Hct levels following the administration of 5-FU. The PK-PD model and simulation represent valuable approaches for quantifying and predicting erythropenia as well as determining individual doses and the time at which the subsequent course of the treatment should start.

Semi-physiological pharmacokinetic-pharmacodynamic modeling and simulation of 5-fluorouracil for the whole time course of alterations in leukocyte, neutrophil and lymphocyte counts in rats.

We aimed to develop a simple pharmacokinetic-pharmacodynamic (PK-PD) model to predict the onset and degree of severe toxic side effects that severely limit the use of many anticancer agents, such as myelosuppression, in rats. Our PK-PD model consisted of a two-compartment PK model, with one compartment representing proliferative cells and some transit compartments consisting of maturing cells, while the other compartment represented circulating blood cells for the PD model. The semi-physiological PK-PD model effectively captured the features of myelosuppression and the degree of the off-target toxicities observed after 5-fluorouracil (5-FU) chemotherapy, and helped simultaneously simulate the whole time course for alterations in leukocyte, neutrophil and lymphocyte counts after 5-FU treatment in rats. Interestingly, by plotting the nadir period of leukocyte, neutrophil and lymphocyte counts as determined by PK-PD analytical simulation curves against the area under the plasma 5-FU concentration-time curve (AUC0-∞) after intravenous administration of 5-FU, a linear relationship was inferred, with r2=0.989, 0.877 and 0.956, respectively. The semi-physiological PK-PD model is a valuable tool for evaluating a variety of novel cancer chemopreventive agents or emerging therapeutic strategies that are difficult to address in humans.

Effects of obesity induced by high-fat diet on the pharmacokinetics of atazanavir in rats.

We studied the effects of obesity on the pharmacokinetics of atazanavir (ATV) using a rat model of high-fat diet-induced obesity (obese rats). The areas under the plasma concentration-time curves for intravenous bolus, oral, and intraportal administration of ATV in obese rats were significantly greater than the corresponding values in control rats. Total plasma clearance of ATV after intravenous bolus injection in the obese rats (0.80 ± 0.07 L/h/kg) was approximately half of that in the control rats (1.55 ± 0.18 L/h/kg). Furthermore, ATV concentration in the plasma-unbound fraction of the obese rats (4.2% ± 2.6%) was significantly lower than that in the control rats (14.2% ± 2.3%). Such differences may result in changes in ATV distribution from the systemic circulation to peripheral or central tissues, and the pharmacological effects of ATV may therefore be reduced in obese patients. Moreover, hepatic extraction in the obese rats (13.5% ± 1.6%) was approximately 62% of that in the controls (21.9% ± 0.96%). These results suggest that hepatic metabolism decreased and that dosing regimens should be carefully evaluated in obese patients. Therefore, in obese patients, it is necessary to pay careful attention to therapeutic drug monitoring data, and the use of specific dosing regimens, as well as that of monitoring system for liver fat accumulation are recommended.

Dissolving microneedles to obtain rapid local anesthetic effect of lidocaine at skin tissue.

Dissolving microneedles (DMs) were applied to lidocaine for local anesthesia of the skin. Three DM array chips were prepared where lidocaine was localized at the acral portion of DMs (type 1), loaded in whole DMs (type 2), and lidocaine was loaded both in whole DMs and the chip (type 3). DM chips were 15-mm diameter with 225 DMs, each 500-µm long with a 300-µm diameter base. The lidocaine contents were (type 1) 0.08 ± 0.01 mg, (type 2) 0.22 ± 0.01 mg and (type 3) 8.52 ± 0.49 mg. Lidocaine was released from type 1 and 2 DM array chips within 10 min. Pharmacological activity of DMs were compared to lidocaine cream by the suppression of idiospasm of hair-removed rat skin. Type 1, 2 and 3 DMs showed faster onset time, 5 min, than lidocaine cream. Type 2 and 3 DMs showed stronger anti-idioplasmic activity than type 1 DMs. Pharmacokinetic study showed that tissue lidocaine levels, 62.8 ± 3.6 (type 1), 89.1 ± 9.9 (type 2) and 131.2 ± 10.2(type 3) µg/g wet weight at 5 min after the removal of DM were obtained higher than lidocaine cream, 26.2 ± 12.5 µg/g wet weight. Those results suggest the usefulness of type 2 DMs to obtain fast onset time for the local anesthesia in the skin.

A predictive biomarker for altered 5-fluorouracil pharmacokinetics following repeated administration in a rat model of colorectal cancer.

The relationship between the plasma ratio of dihydrouracil/uracil (UH2/Ura) and hepatic dihydropyrimidine dehydrogenase (DPD) activity after repeated 5-fluorouracil (5-FU) treatment in rats with colorectal cancer (CRC) was investigated. Repeated intravenous 5-FU bolus injections resulted in a significant decrease in the total clearance (CLtot ) and an increased area under the curve (AUC0-∞ ) in CRC rats. Furthermore, the hepatic DPD levels and the plasma ratio of UH2/Ura decreased significantly and lost their circadian rhythms in CRC rats treated repeatedly with 5-FU, although significant circadian variation in the two parameters was observed in the control CRC rats. Moreover, a significant correlation was found between the plasma ratio of UH2/Ura and hepatic DPD activity in CRC rats untreated and treated with single or repeated 5-FU administration (r(2) = 0.865, p < 0.01). The ratio of UH2/Ura in plasma could be a predictive biomarker of the suppression of hepatic DPD levels during repeated 5-FU-based treatment. Furthermore, by plotting the observed pharmacokinetic parameters of 5-FU against hepatic DPD activity levels predicted by the ratio of UH2/Ura in plasma, AUC0-∞ , CLtot and half-life (t1/2 ) were closely linked to predicted hepatic DPD activity levels. These observations suggest that the factor that significantly influences the AUC0-∞ , CLtot and t1/2 of 5-FU after single or repeated administration of 5-FU is the hepatic DPD activity and it could be assessed by the ratio of UH2/Ura in plasma.

Time-dependent interaction of ritonavir in chronic use: the power balance between inhibition and induction of P-glycoprotein and cytochrome P450 3A.

Ritonavir (RTV) is not only an inhibitor but also an immunoreactive inducer of both P-glycoprotein (Pgp) and cytochrome P450 (CYP) 3A in terms of its chronic use. The aim of present study was to test the hypothesis that the power balance between inhibition effects of RTV and induced activities of Pgp and CYP3A depends on the time after last RTV treatment (TimeR) in the chronic use of RTV; rhodamine 123 (Rho) and midazolam (MDZ) were administered at predetermined TimeR to rats pretreated with RTV for 7 days. After oral administration of Rho and MDZ to rats pretreated with RTV for 7 days, the areas under the plasma concentration-time curve of Rho and MDZ were significantly altered depending on TimeR: 1.27-, 0.79-, 0.95-, and 0.11-fold increases over that of the control for Rho at TimeR = 0, 3, 9, and 24 h and 3.12-, 1.50-, 1.27-, and 0.17-fold increases over that of the control for MDZ at TimeR = 0, 3, 9, and 24 h, respectively. These results revealed the presence of the time-dependent interaction of RTV with concomitant drugs in chronic use and should be taken into account in therapeutic strategies for HIV infection.

Pre-therapeutic assessment of plasma dihydrouracil/uracil ratio for predicting the pharmacokinetic parameters of 5-fluorouracil and tumor growth in a rat model of colorectal cancer.

We investigated the correlation between plasma ratio of dihydrouracil/uracil (UH2/Ura), a possible surrogate biomarker of hepatic dihydropyrimidine dehydrogenase (DPD) activity, and 5-fluorouracil (5-FU) treatment efficacy in rats with colorectal cancer (CRC). 5-FU pharmacokinetic and pharmacodynamic studies were performed using DPD circadian variation in rats with 1,2-dimethylhydrazine-induced CRC. By plotting tumor volume after 5-FU treatment against pre-therapeutic plasma UH2/Ura, we inferred a linear relationship (r(2)=0.988). 5-FU concentration fluctuations induced by DPD activity variation affected tumor volume. In CRC patients receiving proper dosing regimens, plasma UH2/Ura could be an indirect biomarker for predicting 5-FU treatment efficacy, tumor growth, and 5-FU doses.

Pharmacokinetic/pharmacodynamic modeling of 5-fluorouracil by using a biomarker to predict tumor growth in a rat model of colorectal cancer.

We developed a pharmacokinetic/pharmacodynamic (PK/PD) model with the value of the plasma ratio of dihydrouracil (UH2)/uracil (Ura), which is a possible surrogate biomarker of hepatic dihydropyrimidine dehydrogenase activity, determined before 5-fluorouracil (5-FU) treatment to simulate the growth of tumors after 5-FU treatment in rats with colorectal cancer (CRC). In the PK/PD model, the value of the elimination rate constant of 5-FU-ke -was estimated using the plasma UH2/Ura ratio observed before 5-FU treatment for simulating PKs of 5-FU and tumor growth. The PK/PD model with plasma UH2/Ura ratio effectively captured the features of tumor growth and the anticancer effect of 5-FU treatment, which provided reliable parameter estimates. In addition to an appropriate dosing regimen, pretherapeutic assessment of the UH2/Ura ratio in the plasma of CRC patients and PK/PD analysis with the plasma UH2/Ura ratio could enable the development of an optimal therapeutic scheme for each patient.

Method to increase the systemically delivered amount of drug from dissolving microneedles.

To increase the absorbed amount of a drug from dissolving microneedles (DMs), three DM array chips were prepared in which (1) the drug was localized at the acral portion of DMs, (2) the drug was loaded in each whole DM, and (3) the drug was loaded in DMs and the chip. Fluorescein free form (FL) and its sodium salt (FLNa) were used as model drugs. The DM array chip had 15-mm diameter with 225 DMs, each 500-µm long with a 300-µm diameter base. The respective FLNa contents in the three chips were (1) 0.18±0.03, (2) 0.64±0.07, and (3) 10.95±1.07 mg. The FL contents were (1) 0.20±0.01, (2) 0.68±0.03 and (3) 12.47±1.01 mg. The in vitro release of fluorescein from FLNa DMs was faster than that from FL DMs. In vitro permeability experiments showed that (3) produced the greatest increase in the permeability of fluorescein through rat skin, especially in FLNa loaded DMs. In vivo rat absorption study by application of DM array chips to the rat abdominal skin for 6 h demonstrated that the systemically absorbed amount of fluorescein increased from 0.18±0.02 mg, 0.53±0.19 mg, to 5.38±1.99 mg from systems (1) and (2)-(3). By decreasing the application time of DMs to the rat skin, the absorbed amount of fluorescein decreased along with the application time. The physiological state of the skin recovered within 30 min after chip removal. Using a type (3) DM array chip, more than 1.0 mg of water-soluble drug can be delivered to the systemic circulation.

Pharmacokinetics of 5-fluorouracil and increased hepatic dihydropyrimidine dehydrogenase activity levels in 1,2-dimethylhydrazine-induced colorectal cancer model rats.

To investigate the hepatic dihydropyrimidine dehydrogenase (DPD) activity in colorectal cancer (CRC), which is critically important to create a patient-specific dosing regimen, we performed 5-FU pharmacokinetic studies in 1,2-dimethylhydrazine-induced CRC model rats (CRC rats). After rats received 5-FU intravenous (IV) bolus injections, the area under the plasma concentration-time curve (AUC) and elimination half-life (t 1/2) in CRC rats (10.02 ± 0.37 µg h mL(-1), 0.30 ± 0.02 h, respectively) were significantly lower than that in control rats (13.46 ± 1.20 µg h mL(-1), 0.52 ± 0.05 h, respectively), whereas total plasma clearance (CLtot) in CRC rats (2.01 ± 0.07 L h(-1) kg(-1)) was significantly increased compared with that in control rats (1.54 ± 0.14 L h(-1) kg(-1)). Conversely, the avoidance ratio of the hepatic first-pass effect was approximately 20 % lower than that in control rats. Of interest is that hepatic DPD activity levels and the dihydrouracil-uracil ratio (UH2/Ura ratio) in plasma, which may act as a potential biomarker to evaluate hepatic DPD activity levels, were significantly increased in CRC rats. These results suggest that the decrease of hepatic availability in CRC rats is brought about by the increase in intrinsic clearance induced by the increase in DPD activity, resulting in a decrease in AUC and t 1/2 and an increase in CLtot after 5-FU IV bolus injection. Along with a proper dosing regimen for patients with CRC, a hepatic DPD activity monitoring system, such as the determination of UH2/Ura ratio in plasma, is desirable.

Transdermal insulin application system with dissolving microneedles.

BACKGROUND: The aim of this report was to develop a dissolving microneedle (DM) application system, where 225-300 insulin-loaded DMs were formed on a chip. After the heat-sealed sheet is removed, the system covered with the press-through package layer is put on the skin. By pressing with the hand, insulin DMs were inserted into the skin. MATERIALS AND METHODS: Factors affecting the penetration depth of DM were studied using applicator in vitro and in vivo experiments. The penetration depth was determined for rat and human skin. Two-layered DM array chips were prepared to obtain complete absorption of insulin and administered to the rat abdominal skin. Plasma glucose levels were measured for 6 h. By comparing the hypoglycemic effect with that obtained after subcutaneous injection, relative pharmacological availability (RPA) was determined. RESULTS: The penetration depth increased from 21 ± 3 µm to 63 ± 2 µm in proportion to application speed to isolated rat skin, at 0.8-2.2 m/s. Human skin showed similar results in the penetration depth. The in vivo penetration depth was dependent on the force (0.5-2.5 N) and duration (1-10 min), as the secondary application force. The penetration depth was 211 ± 3 µm with a duration of 3 min in the in vivo rat experiment. DM array chips having an insulin-loaded space of 181.2 ± 4.2 and 209 ± 3.9 µm were evaluated in the rat. RPA values of insulin from DMs were 98.1 ± 0.8% and 98.1 ± 3.1%, respectively. CONCLUSIONS: These results suggest the usefulness of the two-layered DM application system for the transdermal delivery of insulin.

Two-layered dissolving microneedles formulated with intermediate-acting insulin.

Two-layered dissolving microneedles (DMs) containing intermediate-acting insulin, protamine sulfate insulin (PSI), were prepared. Then a pharmacodynamic study was performed to evaluate the prolonged hypoglycemic effects in rats. The DMs were approximately 497±5 µm long, with 303±3 µm diameter at their base. The length of the insulin loaded space was 182±4 µm. PSI contents in DMs were 0.51±0.02 IU. A three-month stability study showed that 99.9±1.4% of PSI was recovered at 4 °C. As the temperature increased to 40 °C, recovery decreased to 97.5±2.0%. PSI was released within 5 min from DMs. Hypoglycemic effects of PSI DMs were evaluated in rats where subcutaneous injection preparations were used as references. Total area above the plasma glucose level (% of the pre-dose level) vs. time curve as an index of hypoglycemic effect was 144.0±16.0% h and 243.3±8.5% h for PSI DMs at 1.46 and 3.28 IU/kg. The relative pharmacologic availability of PSI from DMs were 100.2±9.8% and 91.4±4.1%. No significant difference of hypoglycemic curves was found between DMs and injection solutions, which suggests the usefulness of two-layered DMs of PSI for the displacement therapy of sc injection preparation.

Pharmacokinetics and distribution of fluvoxamine to the brain in rats under oxidative stress.

The effects of oxidative stress (OS) on the pharmacokinetics of fluvoxamine (FLV), particularly on FLV distribution in the plasma, were studied in ferric-nitrilotriacetate-induced OS rat models (OS rats). The study protocol involved a continuous FLV infusion (25.0 µg/kg/min). The resulting mean plasma FLV concentration measured in steady state OS rats was 0.13 ± 0.01 µg/mL, which was significantly lower than plasma concentrations measured in control rats (0.19 ± 0.01 µg/mL). Moreover, the mean FLV concentration in the OS rat brain (0.51 ± 0.08 µg/g) was determined to be approximately half the concentration in control rat brains (0.95 ± 0.11 µg/g). The FLV concentrations in both the unbound fraction of plasma and erythrocytes of OS rats were significantly greater than that of control rats. These results suggest the potential attenuation of FLV's pharmacological effects in patients under OS.

Antigen-loaded dissolving microneedle array as a novel tool for percutaneous vaccination.

Antigen-loaded dissolving microneedle array (dMNA) patches were investigated as novel systems for vaccine delivery into the skin, where immuno-competent dendritic cells are densely distributed. We fabricated micron-scale needles arrayed on patches, using chondroitin sulfate mixed with a model antigen, ovalbumin. Insertion of dMNA effectively delivered substantial amounts of ovalbumin into the skin within 3 min and induced robust antigen-specific antibody responses in the sera of mice. The antibody dose-response relationship showed that the efficiency of dMNA patch immunization was comparable to that of conventional intradermal injections. Thus, Antigen-loaded dMNA patches are a promising antigen-delivery system for percutaneous vaccination.