Keizo Fukushima

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.

Incidence of low bioavailability of leuprolide acetate after percutaneous administration to rats by dissolving microneedles

Two-layered dissolving microneedles of which acral portion contained leuprolide acetate (LA) as solid dispersion were prepared with sodium chondroitin sulfate as the base and the systemic absorption efficiency of LA was studied in rats after administration to their abdominal skin. A patch contained 100 dissolving microneedles of which length and basement diameter were 469.8±4.7 μm and 284.5±9.8 μm, where LA content was 14.3±1.6 μg. In vitro dissolution experiment showed that LA was released from dissolving microneedle patch within 3 min. LA was stable in the patch, % recoveries for 3 months were 102.2±1.9-95.3±1.9%. One and half-patch of LA dissolving microneedles were administered to the rat skin and plasma LA concentrations were measured by LC-MS/MS. Plasma LA concentrations increased immediately after administration, and reached to the maximum level at 15 min, where C(max) were 6.0±0.7 and 16.4±0.9 μg/ml, respectively. The AUC were 5.8±0.8 and 14.5±0.4 μg h/ml and BA were 33.8±4.3% and 31.7±0.8%. When LA solution was subcutaneously (s.c.) injected to rats, 50 μg/kg, the BA was 32.0±2.1%. Relative BA of LA from dissolving microneedles against s.c. solution was 105.6±13.5%. The degradation rate of LA in the rat skin tissue homogenate was very fast where the half-life was 16.3±5.7 min. The degradation of LA in the skin tissue was the cause of the low BA of LA after percutaneous administration to rats.

Preparation and pharmaceutical evaluation of nano-fiber matrix supported drug delivery system using the solvent-based electrospinning method.

In this study, utilizing the solvent-based electrospinning (ES) method, which is mainly employed in the textile industry, we prepared nanofiber-based capsules including drugs for controlled-release delivery systems using methacrylic acid copolymer (EUDRAGIT(®) S100, MAC) as a polymer, and evaluated their in vitro drug dissolution profiles and in vivo pharmacokinetics in rats. As the model drugs, uranine (UN) was used as a water-soluble drug and nifedipine (NP) as a water-insoluble drug. The mean diameters of drug free nano-fiber and nano-fiber including NP or UN were 751.5 ± 67.2, 703.3 ± 71.2 and 2477.8 ± 206.1 nm, respectively. X-ray diffraction for the nano-fibrotic sheet showed that UN and/or NP were packed in nano-fiber in an amorphous form. The in vitro release of UN or NP from the nano-fiber packed capsules (NFPC) and milled-powder of nano-fiber packed capsules (MPPC) showed controlled release of UN or NP as compared to capsules of a physical mixture of MAC and each drug. An in vivo pharmacokinetic study in rats after intraduodenal administration of NFPC or MPPC including UN and/or NP clearly demonstrated that application of nano-fibrotic technique as a drug delivery system offers drastic changes in pharmacokinetic profiles for both water-soluble and water-insoluble drugs. The ES method is a useful technique to prepare a nano-fiber like solid dispersion for polar or nonpolar drugs, and has wide potential pharmaceutical applications.

Two-layered dissolving microneedles for percutaneous delivery of sumatriptan in rats

A novel transdermal delivery of sumatriptan (ST) was attempted by application of dissolving microneedle (DM) technology. Dextran DM (d-DM) and hyaluronate DM (h-DM) were prepared by adding ST solution to dextran solution or hyaluronic acid solution. One DM chip, 1.0 × 1.0 cm, contains 100 microneedle arrays in a 10 × 10 matrix. The mean lengths of DMs were 496.6 ± 2.9 μm for h-DM and 494.5 ± 1.3 μm for d-DM. The diameters of the array basement were 295.9 ± 3.9 μm (d-DM) and 291.7 ± 3.0 μm (h-DM), where ST contents were 31.6 ± 4.5 μg and 24.1 ± 0.9 μg. These results suggest that ST was stable in h-DM. Each DM was administered to rat abdominal skin. The maximum plasma ST concentrations, Cmax, and the areas under the plasma ST concentration versus time curves (AUC) were 44.6 ± 4.9 ng/ml and 24.6 ± 3.9 ng · h/ml for h-DM and 38.4 ± 2.7 ng/ml and 14.1 ± 1.5 ng · h/ml for d-DM. The bioavailabilities of ST from DMs were calculated as 100.7 ± 18.8% for h-DM and 93.6 ± 10.2% for d-DM. Good dose dependency was observed on Cmax and AUC. The stability study of ST in DM was performed for 3 months under four different conditions, −80, 4, 23, and 50°C. At the end of incubation period, they were, respectively, 100.0 ± 0.3%, 97.8 ± 0.2%, 98.8 ± 0.2%, and 100.7 ± 0.1%. These suggest the usefulness of DM as a noninvaisive transdermal delivery system of ST to migraine therapy.

Effect of serum lipids on the pharmacokinetics of atazanavir in hyperlipidemic rats.

Atazanavir (ATV) has been successfully used in HIV patients with severe hyperlipidemia (HL); however, little is known about the pharmacokinetics of ATV in HL. The aim of this study was to investigate the pharmacokinetics of ATV in HL. With the increase of serum lipids, the protein binding rate in HL rats (approximately 97%) was significantly higher than that in control (approximately 87%). After intravenous (iv), oral (po) and intraportal (ip) administration of ATV at a dosage of 7 mg/kg, AUCs in HL rats were 12.41, 5.24 and 8.89 microg/mLh, respectively, and were significantly higher than those in control rats (4.09, 1.70 and 3.38 microg/mLh). Despite the decrease of distribution volume (Vd(ss)), the terminal half-life (t(1/2)) in HL tended to be shorter than in control, and hepatic distribution of ATV in HL rats was 4.8-fold increases. These results suggested that the uptake of ATV into liver might counteract the decrease of Vd(ss). On the other hand, there was no significant difference in bioavailability, and the lymphatic transport to AUC showed no statistical change. In conclusion, although the protein binding rate and AUC were significantly increased, the pharmacokinetics of ATV might be tolerated in HL.

Pharmacokinetic and Pharmacodynamic Evaluation of Insulin Dissolving Microneedles in Dogs

BACKGROUND This study tested the hypothesis that dissolving microneedles are a useful transdermal drug delivery system (TDDS) for insulin. METHODS Insulin was loaded on a patch (1.0 cm2) that had 100 dissolving microneedles with chondroitin sulfate by microfabrication technology. Pharmacodynamic evaluation was performed by applying two or four patches to the shaved abdominal skin of dogs, and blood samples were collected for 360 min to measure plasma glucose and insulin levels. In diffusion experiment, microneedles containing fluorescein isothiocyanate-insulin and/or Evans blue were administered to the rat skin, and the diffusion rates of tracers were recorded. RESULTS The mean length, diameter of basement, and drug-loaded space from the top of the microneedles were 492.6 +/- 2.4, 290.0 +/- 3.6, and 316.0 +/- 7.3 microm, respectively. The insulin content was 1.67 +/- 0.17 IU per patch. The time when the minimum plasma glucose level was obtained was 50.0 +/- 8.7 min for two-patch and 82.5 +/- 14.4 min for four-patch studies. A dose-dependent hypoglycemic effect was observed. By comparing the cumulative percentage change in the plasma glucose level between insulin microneedles and solution, the relative physiological availabilities were calculated to be 71.1 +/- 17.8% (for two patches) and 59.3 +/- 4.4% (for four patches). Bioavailabilities of insulin from microneedles were 72.1 +/- 11.6% (for two patches) and 72.4 +/- 8.3% (for four patches). High diffusion rates of fluorescein isothiocyanate-insulin and Evans blue were observed at the administered skin site and correlated well with the high absorption rate of insulin into the systemic circulation. Insulin was stable in dissolving microneedles for 1 month at 4 degrees C; the recovered percentage was 99.2 +/- 13.9%. CONCLUSIONS Dissolving microneedles were demonstrated to be a useful TDDS as an immediate-acting insulin preparation.

Pharmacokinetics of clomipramine, an antidepressant, in poloxamer 407-induced hyperlipidaemic model rats.

Objective  This study was undertaken to investigate the effects of hyperlipidaemia on the pharmacokinetics of clomipramine, an antidepressant, particularly addressing the change of clomipramine distribution to plasma components in poloxamer 407‐induced hyperlipidaemia model rats.

Effects of obesity induced by high‐fat diet on the pharmacokinetics of nelfinavir, a HIV protease inhibitor, in laboratory rats

The effect of obesity induced by a high‐fat diet on the pharmacokinetics (PK) of nelfinavir (NFV) was investigated, focusing on the change of distribution and elimination caused by dyslipidemia and hepatic steatosis.

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.

Effect of streptozotocin-induced diabetes mellitus on the pharmacokinetics of nelfinavir in rats

The HIV protease inhibitor, nelfinavir (NFV), has been used widely for HIV infection. The drug exhibits high binding characteristics to serum protein (unbound fraction: 0.01). The effect of experimentally induced diabetes mellitus on the pharmacokinetics of NFV was investigated, focusing on the change of protein‐binding due to the glycosylation of albumin in streptozotocin‐induced diabetes mellitus rats (diabetic rats). The unbound fraction of NFV in diabetic rats (0.04) was greater than that in the control (0.015). In diabetic rats, although the AUC of NFV was decreased after both intravenous (control: 1.75±0.08, diabetic: 1.36±0.17 µg h/ml) and intraduodenal (control: 1.69±0.25, diabetic: 1.19±0.39 µg h/ml) administrations, the unbound AUC was increased significantly (intravenous, control: 0.026±0.001, diabetic: 0.054±0.007 µg h/ml, intraduodenal, control: 0.025±0.004, diabetic: 0.048±0.016 µg h/ml). The unbound total clearance (control: 131.3±6.0, diabetic: 64.3±8.0 l/h/kg) and the unbound steady state distribution volume (control: 274.0±18.0, diabetic: 123.0±14.0 l/kg) were decreased significantly; therefore, greater pharmacological effects can be expected in diabetes mellitus. The contribution of increasing the unbound fraction to these results was significantly higher. In addition, there were no significant differences in the systemic and hepatic availability, peak time and mean absorption time between the diabetic and control rats, suggesting that diabetes mellitus did not affect the absorption of NFV. Copyright