IVIVC of Octreotide in PLGA-Glucose Microsphere Formulation, Sandostatin® LAR.

In vitro-in vivo correlation (IVIVC) analysis reveals a relationship between in vitro release and in vivo pharmacokinetic response of the drug of interest. Sandostatin LAR Depot (SLD) for endocrine tumors and acromegaly is a sustained-release formulation of octreotide, a cyclic oligomer of 8 amino acids, which prolongs therapeutic efficacy and enhances medication compliance of octreotide. Since the efficacy of SLD is dependent on the pharmacokinetic characteristics of octreotide released from a biodegradable matrix polymer, poly(lactide-co-glycolide)-glucose, of SLD, the IVIVC of SLD is critical for predicting an in vivo behavior of the octreotide. In this study, in vitro release of octreotide from SLD was investigated using the release test media each containing 0.02% or 0.5% surfactant and having different pH values of 7.4 and 5.5. In vivo pharmacokinetic profiles of SLD were determined by LC-MS/MS analysis of the systemic blood concentration of octreotide after the SLD injection to rodents. In IVIVC analysis, the Weibull model was adopted as a drug release model for biodegradable microsphere formulation. The IVIVC analyses revealed the in vitro release test condition of SLD with the highest IVIV correlation coefficient. By applying the in vitro release data to the model derived from the IVIVC analysis, pharmacokinetic parameters of SLD could be predicted with the prediction error of ± 10 ~ 15%. IVIVC analysis and pharmacokinetic prediction model of SLD in our study can be an efficient tool for the development of long-acting pharmaceutical dosage forms.

Mechanisms of controlled stabilizer-free synthesis of gold nanoparticles in liquid aerosol containing plasma.

The interaction between low-temperature plasma and liquid enables highly reactive solution phase chemistry and fast reaction kinetics. In this work, we demonstrate the rapid synthesis of stabilizer-free, spherical and crystalline gold nanoparticles (AuNP). More than 70% of gold ion complex (AuCl- 4) conversion is achieved within a droplet residence time in the plasma of ∼10 ms. The average size of the AuNPs increases with an increase in the droplet residence time and the particle synthesis showed a power threshold effect suggesting the applicability of the classical nucleation theory. Leveraging UV-vis absorption and emission spectroscopy, and nanoparticle size distributions obtained from TEM measurements, we showed that the AuCl- 4 conversion exceeded by 250 times the maximum faradaic efficiency. We identified important roles of both short-lived reducing species including solvated electrons and possibly vacuum ultraviolet (VUV) photons, and long-lived species, H2O2, in the reduction of AuCl- 4. A quantitative investigation was performed by a 1-D reaction-diffusion model which includes transport, plasma-enabled interfacial reduction of AuCl- 4, classical nucleation, monomer absorption and autocatalytic surface growth enabled by H2O2. The model shows good agreement with the experimental results. The timescale analysis of the simulation revealed that nucleation is enabled by fast reduction of gold ions, and autocatalytic growth mainly determines the particle size and is responsible for the majority of the ion precursor conversion while also explaining the excessively large faradaic efficiency found experimentally.

Investigation on Physicochemical Characteristics of a Nanoliposome-Based System for Dual Drug Delivery.

Synergistic effects of multiple drugs with different modes of action are utilized for combinatorial chemotherapy of intractable cancers. Translation of in vitro synergistic effects into the clinic can be realized using an efficient delivery system of the drugs. Despite a few studies on nano-sized liposomes containing erlotinib (ERL) and doxorubicin (DOX) in a single liposome vesicle, reliable and reproducible preparation methods as well as physicochemical characteristics of a non-PEGylated nanoliposome co-encapsulated with ERL and DOX have not been yet elucidated. In this study, ERL-encapsulated nanoliposomes were prepared using the lipid film-hydration method. By ultrasonication using a probe sonicator, the liposome diameter was reduced to less than 200 nm. DOX was loaded into the ERL-encapsulated nanoliposomes using ammonium sulfate (AS)-gradient or pH-gradient method. Effects of DOX-loading conditions on encapsulation efficiency (EE) of the DOX were investigated to determine an efficient drug-loading method. In the EE of DOX, AS-gradient method was more effective than pH gradient. The dual drug-encapsulated nanoliposomes had more than 90% EE of DOX and 30% EE of ERL, respectively. Transmission electron microscopy and selected area electron diffraction analyses of the dual drug-encapsulated nanoliposomes verified the highly oriented DOX-sulfate crystals inside the liposome as well as the less oriented small crystals of ERL in the outermost region of the nanoliposome. The nanoliposomes were stable at different temperatures without an increase of the nanoliposome diameter. The dual drug-encapsulated nanoliposomes showed a time-differential release of ERL and DOX, implying proper sequential releases for their synergism. The preparation methods and the physicochemical characteristics of the dual drug delivery system contribute to the development of the optimal process and more advanced systems for translational researches.

Clinical and biochemical characteristics of nonobese type 2 diabetic patients with glutamic acid decarboxylase antibody in Korea.

We evaluated the prevalence of glutamic acid decarboxylase autoantibody (GADA) in nonobese patients with type 2 diabetes mellitus in Korea and investigated the characteristics of GADA-positive and GADA-negative patients. Two years later, we assessed the progression of beta-cell function in these patients. Of the 647 nonobese patients with type 2 diabetes mellitus enrolled in the study, 10.1% was positive for GADA. Glutamic acid decarboxylase antibody-positive patients had lower fasting and stimulated C-peptide levels compared with GADA-negative patients (1.70 +/- 0.72 vs 1.24 +/- 0.59 microg/L, P < .001; 2.59 +/- 1.51 vs 1.99 +/- 0.82 microg/L, P < .001). Patients treated with insulin had lower fasting and stimulated C-peptide levels than those not treated (1.13 +/- 0.52 vs 1.66 +/- 0.73 microg/L, P = .002; 1.85 +/- 0.69 vs 2.49 +/- 0.91 microg/L, P = .004) and had higher titers of GADA (30.5 +/- 7.3 vs 6.0 +/- 4.8 U/mL, P < .001). In terms of progression of beta-cell function, fasting and stimulated C-peptide levels were significantly lower in GADA-positive patients after 2 years (from 1.24 +/- 0.59 to 0.95 +/- 0.54 microg/L, P = .004; from 1.99 +/- 0.82 to 1.61 +/- 0.77 microg/L, P = .007), whereas no such difference was observed in the GADA-negative patients. We demonstrate that a significant proportion of Korean patients may be positive for GADA; this is consistent with studies of white subjects, although disagrees with previous reports on Korean subjects. By assessing the presence of GADA in Korean type 2 diabetic patients, we are able to predict their course of beta-cell function and identify in advance those who are likely to require insulin treatment.

Association of abdominal obesity with atherosclerosis in type 2 diabetes mellitus (T2DM) in Korea.

The aim of this study was to investigate the relationship between obesity, insulin resistance and atherosclerosis in type 2 diabetes mellitus (T2DM) patients. Total 530 patients with T2DM were included. To evaluate the severity of atherosclerosis, we measured the coronary artery calcification (CAC) score, intima-media thickness (IMT) of the common carotid artery, and the ankle-brachial pressure index (ABPI). Subjects were classified according to body mass index (BMI), a marker of general obesity, and waist-to-hip ratio (WHR), a marker of regional obesity. The insulin sensitivity index (ISI) was measured by the short insulin tolerance test. All subjects were classified into four groups, according to BMI: the under-weight group, the normal-weight (NW) group, the over-weight (OW) group, and the obese (OB) group. WHR and systolic blood pressure, triglycerides (TG), HDL-cholesterol (HDLC), free fatty acids (FFA), fibrinogen, and fasting c-peptide levels were significantly different between BMI groups. TG, HDL-C, FFA, fibrinogen and ISI were significantly different between patients with and without abdominal obesity. In the OW group as well as in the NW group, carotid IMT, ABPI and CAC score were significantly different between patients with and without abdominal obesity. This study indicates that abdominal obesity was associated with atherosclerosis in T2DM patients.

Risk factors associated with the onset and progression of posttransplantation diabetes in renal allograft recipients.

OBJECTIVE: The aim of this study was to assess the incidence of posttransplantation diabetes mellitus (PTDM) in renal allograft recipients and to investigate factors contributing to the onset and progression of PTDM and its underlying pathogenic mechanism(s). RESEARCH DESIGN AND METHODS: A total of 77 patients with normal glucose tolerance (NGT) were enrolled in this study. An oral glucose tolerance test was performed 1 week before transplantation and repeated at 1 and 7 years after transplantation. RESULTS: The overall incidence of PTDM was 39% at 1 year and 35.1% at 7 years posttransplantation. The incidence for each category of PTDM was as follows: persistent PTDM (P-PTDM) (patients who developed diabetes mellitus within 1 year of transplantation and remained diabetic during 7 years), 23.4%; transient PTDM (T-PTDM) (patients who developed diabetes mellitus during the 1st year after transplantation but eventually recovered to have NGT), 15.6%; late PTDM (L-PTDM) (patients who developed diabetes mellitus later than 1 year after transplantation), 11.7%; and non-PTDM during 7 years (N-PTDM7) (patients who did not develop diabetes mellitus during 7 years), 49.3%. Older age (> or = 40 years) at transplantation was a higher risk factor for P-PTDM, whereas a high BMI (> or = 25 kg/m2) and impaired fasting glucose (IFG) at 1 year posttransplantation were higher risk factors for L-PTDM. Impaired insulin secretion rather than insulin resistance was significantly associated with the development of P- and L-PTDM. CONCLUSIONS: Impaired insulin secretion may be the main mechanism for the development of PTDM. Older age at transplantation seems to be associated with P-PTDM, whereas a high BMI and IFG at 1 year after transplantation were associated with L-PTDM.

Effects of growth hormone on insulin resistance and atherosclerotic risk factors in obese type 2 diabetic patients with poor glycaemic control.

OBJECTIVE: We aimed to evaluate the combined effects of GH treatment and diet restriction on lipolysis and anabolism, insulin resistance and atherosclerotic risk factors in obese patients with type 2 diabetes mellitus (T2DM). SUBJECTS: This randomized, double-blind, placebo-controlled study included 24 obese T2DM patients (male : female = 12 : 12, mean age 53.7 +/- 7.2 years) with poor glycaemic control (fasting plasma glucose 10.673 +/- 1.121 mmol/l, HbA(1C) 9.9 +/- 2.3%). Sixteen of these patients were treated with recombinant human GH (1-1.5 units/day, 5 days/week) while undergoing diet restriction and exercise for 12 weeks. METHODS: Anthropometric and bioelectrical impedance measurements were undertaken to determine the lean body mass and total body fat. Computed tomography (CT) was performed to estimate visceral and subcutaneous fat distribution at the umbilicus level and the muscle area of the midthigh. Insulin resistance was measured by the insulin tolerance test (ITT) and by the homeostasis model assessment of insulin resistance (HOMA-IR). RESULTS: The ratios VSR (visceral fat area/subcutaneous fat area) and VMR (visceral fat area/thigh muscle area) were significantly decreased in the GH-treated group compared to the control group. An increase in lean body mass was observed in the GH-treated group. Levels of total cholesterol, triglyceride, free fatty acid (FFA), fibrinogen, and plasminogen activator inhibitor-1 (PAI-1) were significantly decreased after GH treatment. Fasting glucose levels decreased similarly (P < 0.05 anova) in both groups during the treatment period. Fasting C-peptide levels significantly increased, whereas insulin levels significantly decreased, in the GH-treated group, but no changes were observed in the control group. The insulin sensitivity index (ISI) was significantly increased in the GH-treated group (1.3 +/- 1.4 vs. 1.9 +/- 1.0%/min, P < 0.05). CONCLUSIONS: GH treatment in obese T2DM patients with poor glycaemic control is beneficial in decreasing the amount of visceral fats, and may therefore result in improvements in insulin resistance, atherosclerotic risk factors and dyslipidaemia.