Sodium cholate,a solubilizing agent for the necrosis avid radioiodinated hypericin in rabbits with acute myocardial infarction

Abstract

Objectives: We determined whether sodium cholate (NaCh) could act as a solubilizing agent for the necrosis avid iodine-123-labeled hypericin (¹²³I-Hyp) and investigated biodistribution and targetability of this formulation in rabbits with acute myocardial infarction (AMI).

Materials and methods: Solubility of radioiodinated hypericin/hypericin (Hyp) in NaCh solutions was evaluated by microscopy. Hyp with ¹²³I-sodium iodide was performed using hydrogen peroxide as oxidant in 0.06?M NaCh. Radiochemical yield determination and purification were conducted using high performance liquid chromatography. ¹²³I-Hyp was solubilized in 0.06?M NaCh containing 1.9?×?10^?4?M Hyp. The formulation was macroscopically inspected and intravenously injected to five rabbits with AMI. At 24?h, biodistribution was evaluated by tissue gamma counting (TGC) and necrosis targetability was assessed by TGC, autoradiography, fluorescence examination and histology.

Results: Microscopically NaCh at 0.06?M shows the best properties for solubilizing the radioiodinated Hyp/Hyp. ¹²³I-Hyp in 0.06?M NaCh was achieved in 85% with radiochemical purity of 99% after purification. NaCh-dissolved ¹²³I-Hyp/Hyp shows no particles. By TGC, animals exhibited higher (p?=?0.003) radioactivity accumulation in AMI (0.8?±?0.2% ID/g) than in normal myocardium (0.05?±?0.02% ID/g), as confirmed by autoradiography, fluorescence measurement and histology. Among organs, the highest uptake of radioactivity was found in liver (15.7?±?0.6% ID), large (9.7?±?1.0% ID) and small (5.9?±?0.6% ID) intestines.

Conclusion: Necrosis avidity of NaCh-dissolved ¹²³I-Hyp/Hyp and its hepatobiliary excretion were demonstrated. The suitability of NaCh as solubilizing agent of ¹²³I-Hyp for hotspot imaging of AMI was proved.     

Necrosis affinity evaluation of 131I-hypericin in a rat model of induced necrosis

Abstract

Cancers are often with spontaneous or therapeutic necrosis that could be utilized as a generic target for developing new treatments. The purpose of this study was to investigate the biodistribution and pharmacokinetics of radioiodinated hypericin (Hyp), a naturally occurring compound, after intravenous (i.v.) injection in a rat model of liver and muscle necrosis (n?=?42), and evaluate its necrosis affinity. Hyp was labeled with ¹³¹I with labeling efficiency >99%. After incubating in solution/rat plasma for 8 days, radiochemical purity of ¹³¹I-Hyp remained 98.1 and 97.1%, respectively, indicating good in vitro stability. SPECT-CT images at 24?h after i.v. injection of ¹³¹I-Hyp in rats with induced liver and muscle necrosis showed obvious tracer absorption in necrotic tissues. Biodistribution studies revealed that the percentage of the injected dose per gram of tissue (%ID/g) evolved from 1.9 %ID/g at 6?h, through a maximum 3.0 %ID/g at 12?h, to 1.0 %ID/g at 192?h in necrotic liver. Pharmacokinetics studies revealed that the terminal elimination half-life, total body clearance and area under the curve of ¹³¹I-Hyp were 32.7?h, 9.2?L/h/kg and 1.6?MBq/L*h, respectively. These results demonstrated that ¹³¹I-Hyp features a long blood circulation in animals and persistent retention in necrotic tissues. Therefore, ¹³¹I-labeled Hyp could be a broad-spectrum anti-tumor agent with a cost much cheaper relative to the biological agents such as monoclonal antibodies.     

A single-dose toxicity study on non-radioactive iodinated hypericin for a targeted anticancer therapy in mice

Aim:

Hypericin (Hyp) and its radio-derivatives have been investigated in animal models with ischemic heart diseases and malignancies for diagnostic and therapeutic purposes. Before radioiodinated Hyp (¹²³I-Hyp or ¹³¹I-Hyp) can be considered as a clinically useful drug, vigorous evaluations on its chemotoxicity are necessary. In the present study, we examined the toxicity of a single dose of non-radioactive ¹²⁷I-Hyp in normal mice for 24 h and 14 d.

Methods:

Studies were performed on 132 normal mice. ¹²⁷I -Hyp at a clinically relevant dose of 0.1 mg/kg body weight and a 100-times higher dose of 10 mg/kg was intravenously injected into 40 mice. The safety aspects of clinical manifestations, serological biochemistry, and histopathology were assessed. In another 72 mice, ¹²⁷I-Hyp was administered intravenously at assumed values to bracket the value of LD₅₀. The rest 20 mice were used in the control groups.

Results:

At 24 h and 14 d following the injection of ¹²⁷I -Hyp at either 0.1 or 10 mg/kg, all mice tolerated well without mortality or any observable treatment-related symptoms. No significant differences were found in blood biochemical parameters between the test and control groups. All organs presented normal appearances upon histopathological inspection. The value of LD₅₀ of ¹²⁷I-Hyp in mice through intravenous injection was 20.26 mg/kg, with the 95% confidence interval between 18.90 and 21.55 mg/kg.

Conclusion:

The current study reveals a broad safety range of ¹²⁷I-Hyp, which not only supports the use of ¹²³I-Hyp or ¹³¹I-Hyp in the necrosis targeting theragnostic strategy, but also serves as a valuable reference for exploring other possible applications for iodinated Hyp.     

Evaluating the effects of diclofenac sodium and etodolac on renal hemodynamics with contrast-enhanced ultrasonography: a pilot study

Purpose

Contrast-enhanced ultrasonography (CEUS) is a novel approach used for measuring organ perfusion changes. Studies using CEUS to assess the effects of non-steroidal anti-inflammatory drugs (NSAIDs) on renal blood flow (RBF) have not yet been conducted. We aimed to evaluate the effects of NSAIDs on the renal hemodynamics of healthy subjects with CEUS.

Methods

We performed CEUS using the bolus injection method in a total of 10 healthy subjects. Measurements were completed over two study days in a randomized, crossover manner. On each study day, CEUS was performed twice, before and after the administration of NSAIDs. Subjects received an injection of contrast medium and images were recorded. A region-of-interest (ROI) was selected within the renal cortex, signal intensity in the ROI of the kidney was measured and a time-intensity curve (TIC) was automatically generated with attached software.

Results

The mean (±SD) peak intensity decreased significantly after an administration of diclofenac sodium (from 26.0?×?10^?4?±?17.4?×?10^?4 AU to 19.2?×?10^?4?±?12.0?×?10^?4 AU; P?=?0.022), but not significantly with etodolac (from 26.5?×?10^?4?±?9.7?×?10^?4 AU to 25.9?×?10^?4?±?20.8?×?10^?4 AU; P?=?0.474). The mean (±SD) percent reduction in intensity following diclofenac sodium administration was significantly reduced compared with etodolac administration (22.2?±?20.5 % vs. 3.4?±?8.9 %, P?=?0.037).

Conclusions

These finding suggests that diclofenac sodium (P?=?0.022), but not etodolac (P?=?0.474), affects renal hemodynamics even in healthy subjects.     

Changes in pro-inflammatory cytokines and body weight during 6-month risperidone treatment in drug naïve, first-episode schizophrenia

Objective

The present study aimed to examine the changes in pro-inflammatory cytokines and body weight during 6-month risperidone treatment in drug naïve, first-episode schizophrenia.

Methods

Sixty-two drug naïve, first-episode schizophrenia (SZ group) and 60 healthy individuals (control group) were enrolled in the study. Serum interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) levels, and body weight were measured at baseline for both groups, and repeated for the SZ group at five different time points during 6-month risperidone treatment.

Results

At baseline, serum IL-1β, IL-6, and TNF-α levels in the SZ group (53.28?±?12.62, 33.98?±?14.13, 50.08?±?12.86 pg/mL, respectively) were significantly higher than those in the control group (23.49?±?15.27, 15.53?±?7.16, 32.12?±?15.23 pg/mL, respectively) (p's?<?0.001). Within the SZ group, serum IL-1β levels decreased significantly at 2 weeks (48.02?±?16.00 pg/mL, p?<?0.01) and 1 month (44.70?±?16.63 pg/mL, p?<?0.001), but then gradually increased at 2 months (48.49?±?18.87 pg/mL), 3 months (50.59?±?18.48 pg/mL) and 6 months (53.64?±?16.22 pg/mL) to the levels comparable to baseline; serum IL-6 levels changed significantly over the course of treatment (p?=?0.001), but reached the levels comparable to baseline at 6 months (37.13?±?13.23 pg/mL); serum levels of TNF-α increased significantly at 3 months (55.02?±?16.69 pg/mL, p?<?0.01) and 6 months (58.69?±?13.57 pg/mL, p?<?0.001); steady and significant weight gain was observed at each follow-up time point (p's?<?0.001), from 56.71?±?9.25 kg at baseline to 62.72?±?9.53 kg at 6 months.

Conclusions

Risperidone treatment is associated with changes in serum pro-inflammatory cytokines levels and weight. There is an initial anti-inflammatory effect that reduces with treatment, potentially due to its weight gain side effect.     

Interaction between acetaminophen and warfarin in adults receiving long-term oral anticoagulants: a randomized controlled trial

Purpose

We investigated whether acetaminophen, given at 2?g/day and 3?g/day might potentiate the anticoagulant effect of warfarin.

Methods

Forty-five patients on stable warfarin therapy, enrolled in this prospective, randomized, parallel (three arms), placebo-controlled study, received a 10-day regimen of acetaminophen (2?g/day or 3?g/day) or placebo.

Results

The mean maximal INR increase was 0.70?±?0.49 and 0.67?±?0.62 in patients receiving acetaminophen at 2?g/day and 3?g/day, respectively (P?=?0.01 for the respective comparisons versus placebo). The INR increase became significant on day 3 and was independently and significantly predicted by a maximal decrease in factor II (R ²?=?0.36, P?R ²?=?0.46, P?R ²?=?0.563, P?Conclusion Acetaminophen, at 2?g/day or 3?g/day, enhanced the anticoagulant effect of warfarin in stable patients, thus requiring close INR monitoring in the clinical setting.     

High Therapeutic Efficiency of Magnetic Hyperthermia in Xenograft Models Achieved with Moderate Temperature Dosages in the Tumor Area

Purpose

Tumor cells can be effectively inactivated by heating mediated by magnetic nanoparticles. However, optimized nanomaterials to supply thermal stress inside the tumor remain to be identified. The present study investigates the therapeutic effects of magnetic hyperthermia induced by superparamagnetic iron oxide nanoparticles on breast (MDA-MB-231) and pancreatic cancer (BxPC-3) xenografts in mice in vivo.

Methods

Superparamagnetic iron oxide nanoparticles, synthesized either via an aqueous (MF66; average core size 12 nm) or an organic route (OD15; average core size 15 nm) are analyzed in terms of their specific absorption rate (SAR), cell uptake and their effectivity in in vivo hyperthermia treatment.

Results

Exceptionally high SAR values ranging from 658?±?53 W*g_Fe ^?1 for OD15 up to 900?±?22 W*g_Fe ^?1 for MF66 were determined in an alternating magnetic field (AMF, H?=?15.4 kA*m^?1 (19 mT), f?=?435 kHz). Conversion of SAR values into system-independent intrinsic loss power (ILP, 6.4?±?0.5 nH*m²*kg^?1 (OD15) and 8.7?±?0.2 nH*m²*kg^?1 (MF66)) confirmed the markedly high heating potential compared to recently published data. Magnetic hyperthermia after intratumoral nanoparticle injection results in dramatically reduced tumor volume in both cancer models, although the applied temperature dosages measured as CEM43T90 (cumulative equivalent minutes at 43°C) are only between 1 and 24 min. Histological analysis of magnetic hyperthermia treated tumor tissue exhibit alterations in cell viability (apoptosis and necrosis) and show a decreased cell proliferation.

Conclusions

Concluding, the studied magnetic nanoparticles lead to extensive cell death in human tumor xenografts and are considered suitable platforms for future hyperthermic studies.     

Acute cardiac and hemodynamic effects of sildenafil on resistant hypertension

Purpose

Failure to control blood pressure (BP) despite the use of three or more drugs characterizes resistant hypertension (RHTN). Impaired endothelial function is associated with this condition and phosphodiesterase-5 inhibitors (PDE5i)—inhibiting cGMP breakdown—reduce BP in RHTN patients. We hypothesized that acute administration of PDE5i could ameliorate hemodynamic, endothelial parameters and left ventricular diastolic function (LVDF) in RHTN patients. Also, an exploratory analysis was performed to assess the influence of the T-786C endothelial NO synthase polymorphism on those responses.

Methods

Subjects (n?=?26) underwent a 6-month clinical screening for RHTN diagnosis. Increasing doses of oral sildenafil were given at 30 min intervals (37.5, 50 and 100 mg) while continuous non-invasive hemodynamic measures were assessed. LVDF, flow mediated dilation (FMD), nitrite and cGMP levels were also determined.

Results

Mean arterial pressure and total peripheral resistance decreased in all patients (84.17?±?21.04 to 75?±?17.21 mmHg; 1149?±?459.7 to 1037?±?340 dyn.s/cm^?5, respectively). Likewise, sildenafil improved diastolic dysfunction parameters (Left atrial volume: 25?±?5.8 to 20?±?4.4; IVRT: 104?±?19.33 to 88?±?15.22; E/e’ septal: 9.7?±?3.8 to 7.9?±?2.9; E/e’ lateral: 7.7?±?3.4 to 6.4?±?3.2). No statistical changes were found in FMD, nitrite and cGMP with PDE5i.

Conclusion

Our data suggest PDE5i acutely improves diastolic function and hemodynamic profile in RHTN subjects, despite unchanging endothelial dysfunction.     

Uptake of ANG1005, A Novel Paclitaxel Derivative, Through the Blood-Brain Barrier into Brain and Experimental Brain Metastases of Breast Cancer

Purpose

We evaluated the uptake of angiopep-2 paclitaxel conjugate, ANG1005, into brain and brain metastases of breast cancer in rodents. Most anticancer drugs show poor delivery to brain tumors due to limited transport across the blood-brain barrier (BBB). To overcome this, a 19-amino acid peptide (angiopep-2) was developed that binds to low density lipoprotein receptor-related protein (LRP) receptors at the BBB and has the potential to deliver drugs to brain by receptor-mediated transport.

Methods

The transfer coefficient (K_in) for brain influx was measured by in situ rat brain perfusion. Drug distribution was determined at 30 min after i.v. injection in mice bearing intracerebral MDA-MB-231BR metastases of breast cancer.

Results

The BBB K_in for ¹²⁵I-ANG1005 uptake (7.3?±?0.2?×?10^-3 mL/s/g) exceeded that for ³H-paclitaxel (8.5?±?0.5?×?10^-5) by 86-fold. Over 70% of ¹²⁵I-ANG1005 tracer stayed in brain after capillary depletion or vascular washout. Brain ¹²⁵I-ANG1005 uptake was reduced by unlabeled angiopep-2 vector and by LRP ligands, consistent with receptor transport. In vivo uptake of ¹²⁵I-ANG1005 into vascularly corrected brain and brain metastases exceeded that of ¹⁴C-paclitaxel by 4–54-fold.

Conclusions

The results demonstrate that ANG1005 shows significantly improved delivery to brain and brain metastases of breast cancer compared to free paclitaxel.     

Investigation of the Influence of Nephropathy on Monoclonal Antibody Disposition: A Pharmacokinetic Study in a Mouse Model of Diabetic Nephropathy

Purpose

This study employed a mouse model to evaluate the effects of diabetic nephropathy on the pharmacokinetics of 8C2, a murine monoclonal antibody (mAb).

Methods

Streptozotocin (STZ) was administered to mice to induce diabetic nephropathy (125 mg/kg/day?×?2). Mice were grouped (n?=?8–10) based on time after STZ-treatment (control, 1, 2, 3, 4, or 6 weeks), and injected intravenously with 10 mg/kg 8C2. Blood samples were collected up to 7 days, and 8C2 plasma concentrations were determined via immunoassay. Inulin clearance and urinary albumin excretion rate (UAE) were determined to assess renal function.

Results

UAE, inulin clearance, and 8C2 clearance increased significantly following STZ. Comparing control and 6 week STZ-treatment groups, UAE and inulin clearance increased from 25.7?±?3.3 to 99.3?±?13.7 μg/day, and from 421?±?31 to 584?±?78 μl/min. 8C2 clearance increased from 121?±?12.5 to 228?±?61 μl/hr/kg (p?<?0.01). 8C2 clearance was highly correlated with UAE (r²: 0.731). Inclusion of UAE as a covariate in population modeling explained significant residual variability in 8C2 clearance.

Conclusions

The clearance of 8C2 increased significantly in STZ-treated mice. Population pharmacokinetic modeling suggests that UAE has potential for use in predicting mAb clearance in subjects with diabetic nephropathy, possibly assisting in the individualization of mAb dosing.     

The Antitumor Effect of a New Docetaxel-Loaded Microbubble Combined with Low-Frequency Ultrasound In Vitro: Preparation and Parameter Analysis

Purpose

To develop a novel docetaxel (DOC)-loaded lipid microbubbles (MBs) for achieving target therapy and overcoming the poor water-solubility drawback of DOC.

Methods

A novel DOC-loaded microbubble (DOC + MB) was prepared by lyophilization and the physicochemical properties including ultrasound contrast imaging of the liver were measured. The anti-tumor effect of the DOC + MBs combined with low-frequency ultrasound (LFUS; 0.8Hz, 2.56 W/cm², 50% cycle duty) on the DLD-1 cancer cell line was examined using an MTT assay.

Results

The physicochemical properties of the two tested formats of DOC + MBs (1.0 mg and 1.6 mg) was shown: concentration, (6.74?±?0.02)?×?10⁸ bubbles/mL and (8.27?±?0.15)?×?10⁸ bubbles/mL; mean size, 3.296?±?0.004 μm and 3.387?±?0.005 μm; pH value, 6.67?±?0.11 and 6.56?±?0.05; release rate, 3.41% and 12.50%; Zeta potential, ?37.95?±?7.84 mV and ?44.35?±?8.70 mV; and encapsulation efficiency, 54.9?±?6.21% and 46.3?±?5.69%, respectively. Compared with SonoVue, the DOC + MBs similarly enhanced the echo signal of the liver imaging. The anti-tumor effect of the DOC + MBs/LFUS group was significantly better than that of DOC alone and that of the normal MBs/LFUS groups.

Conclusions

The self-made DOC + MBs have potential as a new ultrasound contrast agent and drug-loaded microbubble, and can obviously enhance the antitumor effect of DOC under LFUS exposure.     

Mephedrone pharmacokinetics after intravenous and oral administration in rats: relation to pharmacodynamics

Rationale

Mephedrone (4-methylmethcathinone) is a still poorly known drug of abuse, alternative to ecstasy or cocaine.

Objective

The major aims were to investigate the pharmacokinetics and locomotor activity of mephedrone in rats and provide a pharmacokinetic/pharmacodynamic model.

Methods

Mephedrone was administered to male Sprague–Dawley rats intravenously (10 mg/kg) and orally (30 and 60 mg/kg). Plasma concentrations and metabolites were characterized using LC/MS and LC-MS/MS fragmentation patterns. Locomotor activity was monitored for 180–240 min.

Results

Mephedrone plasma concentrations after i.v. administration fit a two-compartment model (α?=?10.23 h^?1, β?=?1.86 h^?1). After oral administration, peak mephedrone concentrations were achieved between 0.5 and 1 h and declined to undetectable levels at 9 h. The absolute bioavailability of mephedrone was about 10 % and the percentage of mephedrone protein binding was 21.59?±?3.67 %. We have identified five phase I metabolites in rat blood after oral administration. The relationship between brain levels and free plasma concentration was 1.85?±?0.08. Mephedrone induced a dose-dependent increase in locomotor activity, which lasted up to 2 h. The pharmacokinetic–pharmacodynamic model successfully describes the relationship between mephedrone plasma concentrations and its psychostimulant effect.

Conclusions

We suggest a very important first-pass effect for mephedrone after oral administration and an easy access to the central nervous system. The model described might be useful in the estimation and prediction of the onset, magnitude, and time course of mephedrone pharmacodynamics as well as to design new animal models of mephedrone addiction and toxicity.     

Higher dopamine transporter density in Parkinson’s disease patients with depression

Rationale

Depression is a frequent non-motor symptom in Parkinson’s disease (PD) with increasing rates with the progression of the disease. Molecular imaging studies have shown a reduction of dopamine transporter (DAT) density in depressed PD patients (dPD); however, DAT role in the pathophysiology of PD depression is not clear since clinical matching was inappropriate and DAT reduction could be attributed to PD severity.

Objectives

To further examine the role of DAT in PD depression, this study compared thoroughly matched depressed vs. non-depressed PD patients (ndPD).

Materials and methods

Twenty PD patients (n?=?10 ndPD; n?=?10 dPD) matched for age and disease severity were submitted to brain SPECT imaging with [^99mTc]-TRODAT-1, a DAT radioligand. DAT-binding potential was calculated using regions of interest bilaterally drawn in the striatum, caudate, and putamen. Depression was defined according to Beck Depression Inventory (BDI; cut-off >18).

Results

Mean BDI scores were higher in dPD (25.0?±?5.6) than in ndPD patients (8.0?±?1.9, p?<?0.0001). DAT density was greater on dPD especially in the left caudate (dPD 0.87?±?0.19 vs. ndDP 0.69?±?0.18, p?=?0.02) and right putamen (dPD 0.37?±?0.07 vs. ndPD 0.28?±?0.13, p?=?0.03) than in ndPD patients.

Conclusion

Our results suggest that in vivo DAT density is increased in dPD patients as compared to ndPD, suggesting that DAT is implicated in the pathophysiology of PD depression.     

Novel Topical Ophthalmic Formulations for Management of Glaucoma

Purpose

Preparation of topical ophthalmic formulations containing brimonidine-loaded nanoparticles prepared from various biodegradable polymers—PCL, PLA and PLGA—for sustained release of brimonidine as a once daily regimen for management of glaucoma.

Methods

Nanoparticles were prepared using spontaneous emulsification solvent diffusion method then characterized regarding their particle size, zeta potential, morphology and drug contents. Brimonidine-loaded nanoparticles were incorporated into eye drops, temperature-triggered in situ gelling system and preformed gel and characterized regarding their pH, viscosity, uniformity of drug contents, in vitro release study, in vitro cytotoxicity and in vivo intraocular pressure (IOP) lowering effects.

Results

The results of optimized brimonidine-loaded PCL-, PLGA- and PLA-NPs respectively, are: particle sizes of 117.33?±?4.58 nm, 125.67?±?5.15 nm and 131.67?±?3.79 nm; zeta potentials of ?18.5?±?2.87 mV, ?21.82?±?2.7 mV and ?28.11?±?2.21 mV; and encapsulation efficiencies of 77.97?±?1.38%, 68.65?±?3.35% and 73.52?±?2.92%. TEM analyses revealed that all NPs have spherical shapes with dense core and distinct coat. In vitro release data showed a sustained release without any burst effect with Higuchi non-Fickian diffusion mechanism. Cytotoxicity studies revealed that all formulations are non-toxic. Also all formulations possessed a sustained IOP lowering effect compared to Alphagan® P eye drops.

Conclusions

Our formulations showed prolonged management of glaucoma that should meet with better patient compliance as a once-daily formulation.     

Desipramine prevents cardiac gap junction uncoupling

Background and purpose

Uncoupling of cardiac gap junction channels is an important arrhythmogenic mechanism in ischemia/reperfusion. Antiarrhythmic peptide AAP10 (H-Gly-Ala-Gly-Hyp-Pro-Tyr-CONH₂) has been shown to prevent acidosis-induced uncoupling and ischemia-related increase in dispersion. Previous structure–effect investigations and subsequent computer modeling studies indicated that the tricyclic antidepressant desipramine may exert similar effects as AAP10.

Methods

We assessed the binding of ¹⁴C-AAP10 to membranes of rabbit cardiac ventricles and its displacement with desipramine in a classical radioligand binding and competition study. Gap junction currents were measured between isolated pairs of human atrial cardiomyocytes under normal and acidotic (pH 6.3) conditions with or without 1?μmol/l desipramine using dual whole-cell voltage clamp. The effect of 1?μmol/l desipramine was assessed in isolated rabbit hearts (Langendorff technique) undergoing local ischemia by coronary occlusion with 256-channel electrophysiological mapping and subsequent analysis of connexin43 (Cx43) expression, phosphorylation (Western blot), and subcellular localization (immunohistology).

Results

We found saturable ¹⁴C-AAP10 binding to cardiac membranes (K _D, 0.29?±?0.11?nmol/l; B _max, 42.5?±?7.2 pmol/mg) which could be displaced by desipramine with a K _D.High?=?0.14?μmol/l and a K _D.Low?=?22?μmol/l. Acidosis reduced the gap junction conductance in human cardiomyocyte pairs from 24.1?±?4.7 to 11.5?±?2.5 nS, which could be significantly reversed by desipramine (26.6?±?4.8 nS). In isolated hearts, ischemia resulted in significantly increased dispersion of activation–recovery intervals, loss of membrane Cx43, and dephosphorylation of Cx43, which all could be prevented by desipramine.

Conclusion

Desipramine seems to prevent the uncoupling of cardiac gap junctions and ischemia-related increase in dispersion.     

The relationship between antipsychotic D2 occupancy and change in frontal metabolism and working memory

Rationale

The effects of aripiprazole on cognitive function are obscure, possibly due to the difficulty in disentangling the specific effects on cognitive function from effects secondary to the improvement of other schizophrenic symptoms. This prompts the necessity of using an intermediate biomarker relating the drug effect on the brain to change in cognitive function.

Objectives

To explore the effect of aripiprazole on cognitive function, we measured changes in frontal metabolism as an intermediate biomarker and sought to determine its relationship with D₂ receptor occupancy and changes in working memory.

Methods

Fifteen healthy male volunteers participated in the study. Serial positron emission tomography (PET) scans with [¹¹C]raclopride and [¹⁸?F]FDG were conducted 1 day before and 2 days after the administration of aripiprazole. The subjects performed the N-back task just after finishing the [¹⁸?F]FDG scan.

Results

The mean (±SD) D₂ receptor occupancies were 22.2?±?16.0 % in the 2 mg group, 35.5?±?3.6 % in the 5 mg group, 63.2?±?9.9 % in the 10 mg group and 72.8?±?2.1 % in the 30 mg group. The frontal metabolism was significantly decreased after the administration of aripiprazole (t?=?2.705, df?=?14, p?=?0.017). Greater striatal D₂ receptor occupancy was related to greater decrease in frontal metabolism (r?=??0.659, p?=?0.010), and greater reduction in frontal metabolism was associated with longer reaction times (r?=??0.597, p?=?0.019) under the greatest task load.

Conclusions

Aripiprazole can affect cognitive function and alter frontal metabolic function. The changes in these functions are linked to greater D₂ receptor occupancy. This suggests that it may be important to find the lowest effective dose of aripiprazole in order to prevent adverse cognitive effects.     

Paliperidone-Loaded Mucoadhesive Microemulsion in Treatment of Schizophrenia: Formulation Consideration

Purpose

This paper describes formulation considerations and in vitro evaluation of a microemulsion drug delivery system designed for intranasal administration of Paliperidone.

Methods

Drug-loaded microemulsions were successfully prepared by a water titration. Prepared formulations were subjected to physicochemical characterization, and evaluated for in vitro diffusion, nasal cilio toxicity, and in vitro mucoadhesion.

Results

The microemulsion, containing 4 % oleic acid, 30 % surfactant mixture of [Labrasol/Cremophor RH 40 (1:1)]/[Transcutol P] (3:1) and 66 % (wt/wt) aqueous phase, that displayed a 99.93 % optical transparency, globule sizes of 20.01?±?1.28 nm, and a polydispersity index of 0.117?±?0.034 was selected for the incorporation of polyelectrolytic polymer (polycarbophil) as the mucoadhesive component. The mucoadhesive microemulsion formulation of Paliperidone that contains 0.5 % by weight of polycarbophil displayed higher in vitro mucoadhesive potential (18.0?±?2.5 min) and diffusion coefficient (3.83?×?10^?6?±?0.019?×?10^?6) than microemulsion. Also, they were found to be free from nasal ciliotoxicity and had stability for 6 months.

Conclusion

The in vitro studies demonstrated the potential of developing mucoadhesive microemulsion formulation for intranasal delivery of Paliperidone.     

In Vitro,In Vivo,and In Silico Evaluation of the Bioresponsive Behavior of an Intelligent Intraocular Implant

Purpose

An autofeedback complex polymeric platform was used in the design of an intelligent intraocular implant—the I³—using stimuli-responsive polymers, producing a smart release system capable of delivering therapeutic levels of an anti-inflammatory agent (indomethacin) and antibiotic (ciprofloxacin) for posterior segment disorders of the eye in response to inflammation.

Methods

Physicochemical and physicomechanical analysis of the I³ was undertaken to explicate the highly crosslinked make-up and ‘on-off’ inflammation-responsive performance of the I³. In addition, energetic profiles for important complexation reactions were generated using Molecular Mechanics Energy Relationships by exploring the spatial disposition of energy minimized molecular structures. Furthermore, preliminary in vivo determination of the inflammation-responsiveness of the I³ was ascertained following implantation in the normal and inflamed rabbit eye.

Results

In silico modeling simulating a pathological inflammatory intraocular state highlighted the interaction potential of hydroxyl radicals with the selected polysaccharides comprising the I³. The intricately crosslinked polymeric system forming the I³ thus responded at an innate level predicted by its molecular make-up to inflammatory conditions as indicated by the results of the drug release studies, rheological analysis, magnetic resonance imaging and scanning electron microscopic imaging. In vivo drug release analysis demonstrated indomethacin levels of 0.749?±?0.126 μg/mL and 1.168?±?0.186 μg/mL, and ciprofloxacin levels of 1.181?±?0.150 μg/mL and 6.653?±?0.605 μg/mL in the normal and inflamed eye, respectively.

Conclusions

Extensive in vitro, molecular, and in vivo characterization therefore highlighted successful inflammation-responsiveness of the I³. The I³ is a proposed step forward from other described ocular systems owing to its combined bioresponsive, nano-enabled architecture.     

A fenugreek seed extract selectively reduces spontaneous fat intake in overweight subjects

Purpose

Fenugreek seeds (Trigonella foenum-graecum L.) have long been used as a herbal medicine for treating metabolic and nutritive dysfunctions. They have been shown to modulate feeding behaviour in animals. We have recently observed a selective decrease in fat consumption in healthy normal weight volunteers treated with a hydro-alcoholic seed extract. However, strong clinical data on the effects of fenugreek seeds on energy intake are lacking, especially in overweight individuals. The aim of our study was to investigate the effects of a repeated administration of a fenugreek seed extract on the eating behaviour of overweight subjects.

Methods

Thirty-nine healthy overweight male volunteers completed a 6-week double-blind randomized placebo-controlled parallel trial of a fixed dose of a fenugreek seed extract. Main endpoints were energy intake (dietary records and meal test), weight, fasting and post-absorptive glucose and insulin, appetite/satiety scores and oxidative parameters.

Results

Daily fat consumption, expressed as the ratio fat reported energy intake/total energy expenditure (fat-REI/TEE), was significantly decreased in our overweight subjects administered the fenugreek seed extract relative to those receiving the placebo (fat-REI/TEE 0.26?±?0.02 vs. 0.30?±?0.01, respectively; P?=?0.032). We also observed a significant decrease in the insulin/glucose ratio in subjects treated with fenugreek seed extract relative to the placebo group (0.89?±?0.09 vs. 1.06?±?0.10 mUI mmol^?1, respectively; P?=?0.044). No significant effect was observed on weight, appetite/satiety scores or oxidative parameters.

Conclusion

The repeated administration of a fenugreek seed extract slightly but significantly decreased dietary fat consumption in healthy overweight subjects in this short-term study.     

Pharmacokinetics and protein binding of cefazolin in morbidly obese patients

Purpose

The aim of this study was to assess the pharmacokinetics and protein binding of cefazolin in morbidly obese patients undergoing bariatric surgery, to study the influence of bodyweight measures and age on pharmacokinetic parameters and to evaluate unbound cefazolin concentrations over time in this population.

Methods

Twenty morbidly obese patients (bodyweight 112?C260?kg, body mass index 38?C79?kg?m^?2) were studied following the administration of cefazolin 2 g at induction of anaesthesia. Blood samples were collected up to 4 h post-dosing to determine total and unbound plasma cefazolin concentrations. Non-compartmental pharmacokinetic data analysis was performed.

Results

Cefazolin clearance was 4.2 ± 1.0 L?h^?1 (mean ± standard deviation) and showed a negative correlation with age (p?=?0.003) but not with bodyweight measures (p?>?0.05). Volume of distribution was 13.0 ± 3.1 L and correlated positively with bodyweight measures (p????0.001). Saturable protein binding was observed with a median protein binding of 79% (interquartile range 74?C82), which proved similar to reported protein binding in non-obese patients. In all patients, unbound cefazolin concentrations remained above 1?mg?L^?1 (minimal inhibitory concentration for 90% (MIC₉₀) of methicillin-sensitive isolates of Staphylococcus aureus in Europe) until 4 h post-dosing.

Conclusions

Younger age??and not bodyweight??was significantly associated with higher cefazolin clearance. However, as in all patients with bodyweights up to 260?kg, unbound plasma cefazolin concentrations remained above 1?mg?L^?1 until 4 h after the intravenous administration of a 2-g dose. As such, re-dosing within 4 h or dosing with another antibiotic class should only be considered in the case of a higher MIC₉₀ of the local isolates.