Through-vial impedance spectroscopy of critical events during the freezing stage of the lyophilization cycle: The example of the impact of sucrose on the crystallization of mannitol

The aim of this work was to evaluate the application of through-vial impedance spectroscopy in the measurement of eutectic crystallization during the freezing stage of the lyophilisation cycle.Impedance measurements of various sugar solutions (mannitol 5%, 10% and 15% w/v, sucrose 5% w/v and mannitol 5% w/v, and sucrose 5% w/v solutions) were taken during a freeze–thaw cycle, over a frequency range 10–10⁶ Hz with a scan interval of 1.5 min, using measurement vials with externally attached electrodes connected to a high resolution impedance analyzer.Estimates for the electrical resistance of the mannitol solutions record the exothermic crystallization of mannitol at a temperature of −24 °C during the temperature ramp down stage of the freezing cycle, which is in close agreement with the off-line DSC measurement of −22 °C. The freezing profile of a 5% mannitol solution with 5% sucrose (a component that does not crystallize in the frozen solution) demonstrated the inhibition of mannitol crystallization (with the implication that the product will then require sub-T_g′ freezing and drying).The work suggests a role for through-vial impedance spectroscopy in the concurrent development of the product formulation and freeze drying cycle without the uncertainty introduced when using off-line date to define the critical process parameters.     

Tissue accumulation and toxicity of isothiazolinone in Ctenopharyngodon idellus (grass carp): Association with P-glycoprotein expression and location within tissues

Isothiazolinone is widely used as a broad-spectrum fungicide in various industries, such as oil, paper, pesticide, dyes, tanning and cosmetics. There is an increasing concern over protection of the aquatic environment due to its large-scale use. The acute toxicity (LC₅₀) of isothiazolinone in Ctenopharyngodon idellus was investigated. The residual time and accumulation in tissues, P-glycoprotein mRNA level and localization of P-glycoprotein in the liver and kidney were also analyzed. The LC₅₀ (48 h) values of isothiazolinone to C. idellus were 0.53 ± 0.17 mg/L and 0.41 ± 0.08 mg/L at 15 °C and 25 °C, respectively. The LC₅₀ values decreased as the temperature increased. The accumulation of isothiazolinone in livers and kidneys in the high temperature group (25 °C) was significantly greater than that of the low temperature group (15 °C). Prolonged tissue residual time of isothiazolinone was seen in all the groups. There were significant differences in P-glycoprotein mRNA expression between isothiazolinone-treated groups and control samples (P < 0.05–0.01). Temperature affected accumulation and toxicity of isothiazolinone.     

Spray freeze drying for dry powder inhalation of nanoparticles

Formulating nanoparticles for delivery to the deep lung is complex and many techniques fail in terms of nanoparticle stability. Spray freeze drying (SFD) is suggested here for the production of inhalable nanocomposite microcarriers (NCM). Different nanostructures were prepared and characterized including polymeric and lipid nanoparticles. Nanoparticle suspensions were co-sprayed with a suitable cryoprotectant into a cooled, stainless steel spray tower, followed by freeze drying to form a dry powder while equivalent compositions were spray dried (SD) as controls. SFD-NCM possess larger specific surface areas (67–77 m²/g) and lower densities (0.02 g/cm³) than their corresponding SD-NCM. With the exception of NCM of lipid based nanocarriers, SFD produced NCM with a mass median aerodynamic diameter (MMAD) of 3.0 ± 0.5 μm and fine particle fraction (FPF ⩽ 5.2 μm) of 45 ± 1.6% with aerodynamic performances similar to SD-NCM. However, SFD was superior to SD in terms of maintaining the particle size of all the investigated polymeric and lipid nanocarriers following reconstitution (S_f/S_i ratio for SFD ≈ 1 versus >1.5 for SD). The SFD into cooled air proved to be an efficient technique to prepare NCM for pulmonary delivery while maintaining the stability of the nanoparticles.     

Investigation of PEG Crystallization in Frozen PEG-Sucrose-Water Solutions. I. Characterization of the Nonequilibrium Behavior during Freeze-Thawing

Our objective was to characterize the nonequilibrium thermal behavior of frozen aqueous solutions containing PEG and sucrose. Aqueous solutions of (i) sucrose (10%, w/v) with different concentrations of PEG (1–20%, w/v), and (ii) PEG (10%, w/v) with different concentrations of sucrose (2–20%, w/v), were cooled to ? 70°C at 5°C/min and heated to 25°C at 2°C/min in a differential scanning calorimeter. Annealing was performed at temperatures ranging from ? 50 to ? 20°C for 2 or 6 h. Similar experiments were also performed in the low-temperature stage of a powder X-ray diffractometer. A limited number of additional DSC experiments were performed wherein the samples were cooled to ? 100°C. In unannealed systems with a fixed sucrose concentration (10%, w/v), the T′_g decreased from ? 35 to ? 48°C when PEG concentration was increased from 1% to 20% (w/v). On annealing at ? 25°C, PEG crystallized. This was evident from the increase in T′_g and the appearance of a secondary melting endotherm in the DSC. Low- temperature XRD provided direct evidence of PEG crystallization. Annealing at temperatures ≤?40°C did not result in crystallization and a devitrification event was observed above the T′_g. In unannealed systems with a fixed PEG concentration (10%, w/v), the T′_g increased from ? 50 to ? 40°C when sucrose concentration was increased from 5% to 50%, w/v. As the annealing time increased (at ? 25°C), the T′_g approached that of a sucrose-water system, reflecting progressive PEG crystallization. A second glass transition at ~? 65°C was evident in unannealed systems [10%, w/v sucrose and 10 (or 20%), w/v PEG] cooled to ? 100°C. Investigation of the nonequilibrium behavior of frozen PEG-sucrose-water ternary system revealed phase separation in the freeze-concentrate. Annealing facilitated PEG crystallization.     

Preparation and characterisation of novel chlorothiazide potassium solid-state salt forms: Intermolecular self assembly suprastructures

Chlorothiazide (CTZ) is a poorly soluble diuretic agent. The aim of the present work was to produce and characterise a potassium salt form of chlorothiazide which has the potential advantages of improved aqueous solubility and potassium supplementation. A number of novel potassium salt forms of CTZ (CTZK) were prepared: CTZK monohydrate (form I), CTZK dihydrate (form II), anhydrous CTZK (form III), CTZK monohydrate hemiethanolate (form IV) and a desolvate of CTZK monohydrate hemiethanolate (form V). These salt forms were characterised by thermal analysis, PXRD, NMR, elemental analysis, FTIR, Karl Fisher titrimetry, ICP-MS and GC–MS. The ethanol-free CTZK forms were also characterised by dynamic vapour sorption analysis (DVS). CTZK form I was stable (in the DVS) over the range 0–60% RH. The dihydrate form of the salt was stable (in the DVS) over a broader range of relative humidities, 10–90% RH at 25 °C. CTZK form II was less hygroscopic at high humidities (70–90% RH) than the previously reported CTZNa dihydrate. Single crystal X-ray analysis indicated that chlorothiazide potassium, crystallised from water or water/acetone mixture, formed a dihydrated polymeric-like intermolecular self-assembly (ISA) suprastructure. The ISA coordination was determined to be: (CTZ)₃·K·(H₂O)₂(CTZ)₂·(H₂O)₂·K·(CTZ)₃ (monoclinic, space group: C2/c, single crystal cell parameters: a = 18.328(4) Å, b = 7.3662(16) Å, c = 19.993(5) Å, α = 90°, β = 99.729(3)°, γ = 90°). When CTZK was crystallised from ethanol, a monohydrate hemiethanolate ISA was formed, described as (CTZ)₃·K·CTZ·(H₂O)₂·CTZ·K·(CTZ)₂ (triclinic, space group: P-1, single crystal cell parameters: a = 7.078(3) Å, b = 9.842(5) Å, c = 21.994(11) Å, α = 87.522(13)°, β = 84.064(14)°, γ = 78.822(12)°). The aqueous solubility of CTZK dihydrate, was determined to be 78.71 ± 1.82 mg/ml, approximately 400-fold higher than chlorothiazide, indicating a biopharmaceutical advantage associated with the potassium salt form.     

A methodological evaluation and predictive in silico investigation into the multi-functionality of arginine in directly compressed tablets

The acceleration of solid dosage form product development can be facilitated by the inclusion of excipients that exhibit poly-/multi-functionality with reduction of the time invested in multiple excipient optimisations. Because active pharmaceutical ingredients (APIs) and tablet excipients present diverse densification behaviours upon compaction, the involvement of these different powders during compaction makes the compaction process very complicated. The aim of this study was to assess the macrometric characteristics and distribution of surface charges of two powders: indomethacin (IND) and arginine (ARG); and evaluate their impact on the densification properties of the two powders. Response surface modelling (RSM) was employed to predict the effect of two independent variables; Compression pressure (F) and ARG percentage (R) in binary mixtures on the properties of resultant tablets. The study looked at three responses namely; porosity (P), tensile strength (S) and disintegration time (T). Micrometric studies showed that IND had a higher charge density (net charge to mass ratio) when compared to ARG; nonetheless, ARG demonstrated good compaction properties with high plasticity (Y = 28.01 MPa). Therefore, ARG as filler to IND tablets was associated with better mechanical properties of the tablets (tablet tensile strength (σ) increased from 0.2 ± 0.05 N/mm² to 2.85 ± 0.36 N/mm² upon adding ARG at molar ratio of 8:1 to IND). Moreover, tablets’ disintegration time was shortened to reach few seconds in some of the formulations. RSM revealed tablet porosity to be affected by both compression pressure and ARG ratio for IND/ARG physical mixtures (PMs). Conversely, the tensile strength (σ) and disintegration time (T) for the PMs were influenced by the compression pressure, ARG ratio and their interactive term (FR); and a strong correlation was observed between the experimental results and the predicted data for tablet porosity. This work provides clear evidence of the multi-functionality of ARG as filler, binder and disintegrant for directly compressed tablets.     

Preparation of a fast dissolving oral thin film containing dexamethasone: A possible application to antiemesis during cancer chemotherapy

We prepared fast dissolving oral thin film that contains dexamethasone and base materials, including microcrystalline cellulose, polyethylene glycol, hydroxypropylmethyl cellulose, polysorbate 80 and low-substituted hydroxypropyl cellulose. This preparation showed excellent uniformity and stability, when stored at 40 °C and 75% in humidity for up to 24 weeks. The film was disintegrated within 15 s after immersion into distilled water. The dissolution test showed that approximately 90% of dexamethasone was dissolved within 5 min. Subsequently, pharmacokinetic properties of dexamethasone were compared in rats with oral administration of 4 mg dexamethasone suspension or topical application of the film preparation containing 4 mg dexamethasone to the oral cavity. Pharmacokinetic parameters were similar between the two groups in which C_max (h), T_max (μg/mL), AUC (μg/mL/h) and half-life (h) were 12.7 ± 6.6 (mean ± SD, N = 10), 3.4 ± 1.4, 93.6 ± 37.8 and 1.66 ± 0.07, respectively, for oral suspension and 13.3 ± 4.0, 3.2 ± 1.0, 98.0 ± 22.3 and 1.65 ± 0.06, respectively, for film preparation. These findings suggest that the fast dissolving oral thin film containing dexamethasone is likely to become one of choices of dexamethasone preparations for antiemesis during cancer chemotherapy.     

Changes in ambient temperature differentially alter the thermoregulatory,cardiac and locomotor stimulant effects of 4-methylmethcathinone (mephedrone)

BackgroundThe substituted cathinone compound known as mephedrone (4-methylmethcathinone; 4-MMC) has become popular with recreational users of psychomotor-stimulant compounds. Only recently have the first preclinical studies provided information about this drug in the scientific literature; nevertheless, media reports have led to drug control actions in the UK and across several US states. Rodent studies indicate that 4-MMC exhibits neuropharmacological similarity to 3,4-methylenedioxymethamphetamine (MDMA) and prompt investigation of the thermoregulatory, cardiac and locomotor effects of 4-MMC. This study focuses on the role of ambient temperature, which has been shown to shift the effects of MDMA from hyperthermic to hypothermic.MethodsMale Sprague-Dawley rats were monitored after subcutaneous administration of 4-MMC (1.0–5.6 mg/kg) using an implantable radiotelemetry system under conditions of low (20 °C) and high (30 °C) ambient temperature.ResultsA pharmacokinetic study found a T_max of 0.25 h and a C_max of 1206 ng/ml after 5.6 mg/kg 4-MMC. A dose-dependent reduction of body temperature was produced by 4-MMC at 20 °C but there was no temperature change at 30 °C. Increased locomotor activity was observed after 4-MMC administration under both ambient temperatures, however, significantly more activity was observed at 30 °C. Heart rate was slowed by 1.0 and 5.6 mg/kg 4-MMC at 20 °C, and was slower in the 30 °C vs. 20 °C condition across all treatments.ConclusionThese results show that the cathinone analog 4-MMC exhibits in vivo thermoregulatory properties that are distinct from those produced by MDMA.     

Impact of iron oxide nanoparticles on brain,heart, lung,liver and kidneys mitochondrial respiratory chain complexes activities and coupling

The present study evaluates the effects of iron oxide nanoparticles (ION) on mitochondrial respiratory chain complexes activities in five organs characterized by different oxidative capacities and strongly involved in body detoxification. Isolated mitochondria were extracted from brain, heart, lung, liver and kidneys in twelve Wistar rats (8 weeks) using differential centrifugations. Maximal oxidative capacities (Vmax), mitochondrial respiratory chain complexes activity using succinate (Vsucc, complexes II, III, and IV activities) or N, N, N′, N′-tetramethyl-p-phenylenediaminedihydrochloride (tmpd)/ascorbate (Vtmpd, complex IV activity) and, mitochondrial coupling (Vmax/Vo) were determined in controls and after exposure to 100, 200, 300 and 500 μg/ml Fe₃O₄. Data showed that baseline maximal oxidative capacities were 26.3 ± 4.7, 48.9 ± 4.6, 11.3 ± 1.3, 27.0 ± 2.5 and 13.4 ± 1.7 μmol O₂/min/g protein in brain, heart, lung, liver, and kidneys mitochondria, respectively. Complexes II, III, and IV activities also significantly differed between the five organs. Interestingly, as compared to baseline values and in all tissues examined, exposure to ION did not alter mitochondrial respiratory chain complexes activities whatever the nanoparticles (NPs) concentration used. Thus, ION did not show any toxicity on mitochondrial coupling and respiratory chain complexes I, II, III, and IV activities in these five major organs.     

Occurrence and exposure to polycyclic aromatic hydrocarbons in kindling-free-charcoal grilled meat products in Taiwan

This study aimed to determine the contents of 16 PAHs in kindling-free-charcoal grilled meat and seafood products by GC–MS coupled with a QuEChERS method, and estimate the potential risk associated with consumption of those products in Taiwan. Results showed that the total PAHs contents ranged from 6.3 ± 0.9 to 238.8 ± 8.3 ng/g in poultry meat, 0.1 ± 0.0–547.5 ± 12.2 ng/g in red meat, and 6.6 ± 1.4–249.7 ± 6.4 ng/g in seafood products. Among various PAHs, the highly carcinogenic benzo[a]pyrene was detected in chicken breast grilled at 84 °C (30 min), chicken heart at 100 °C (26 min), chicken drumstick at 74 °C (20 min), duck drumstick at 85 °C (40 min), and lamb steak at 88 °C (12 min), with its level amounting to 1.3 ± 0.0, 2.4 ± 0.1, 4.0 ± 1.3, 3.1 ± 0.0, and 5.8 ± 0.5 ng/g, respectively. The generation of PAHs was associated with grilling time, temperature and fat content. Risk assessment of dietary exposure to PAHs revealed toxicity equivalent to range from ND – 6.174 ± 0.505 μg/g and margin of exposure was >10,000, which agreed with the EFSA’s definition of low public health concern. The lifelong average daily PAHs intake was higher for adults than for elderly people in Taiwan, however, consumption of kindling-free-charcoal grilled meat should not be a public health concern based on cancer risk potency.     

Penetration of doripenem into prostatic tissue following intravenous administration in prostatectomy patients

This study examined the prostatic penetration of doripenem in prostatectomy patients. Doripenem 500 mg was administered by a 0.5-h infusion and venous blood and prostatic tissue samples were obtained up to 5 h afterwards. Drug concentrations in plasma and prostatic tissue were measured chromatographically. The observed maximum concentration (C_max) (mean ± standard deviation; n = 9) was 27.5 ± 5.1 μg/mL in plasma and 5.09 ± 1.94 μg/g in prostate tissue and the prostate/plasma C_max ratio was 0.189 ± 0.078. The area under the drug concentration–time curve (AUC) was 49.7 ± 6.9 μg h/mL in plasma and 3.93 ± 1.89 μg h/g in prostate tissue and the prostate/plasma AUC ratio was 0.081 ± 0.047. Based on a three-compartment pharmacokinetic analysis, average drug exposure times above 0.25 μg/mL (the minimum inhibitory concentration for isolates of common pathogens) in the prostate were 23.2% for 500 mg once daily, 46.2% for 500 mg twice daily and 69.9% for 500 mg three times daily. The 500-mg regimens all achieved the drug exposure time target (bacteriostatic 20% or bactericidal 40%) in the prostate, despite the relatively low penetrability of doripenem.     

Investigation of PEG Crystallization in Frozen PEG–Sucrose–Water Solutions: II. Characterization of the Equilibrium Behavior During Freeze-Thawing

Our objective was to characterize, by DSC and XRD, the equilibrium thermal behavior of frozen aqueous solutions containing polyethylene glycol (PEG) and sucrose. Aqueous solutions of (i) PEG (2.5–50% w/w), (ii) sucrose (10% w/v) with different concentrations of PEG (1–20% w/v), and (iii) PEG (2% or 10% w/v) with different concentrations of sucrose (2–20% w/v), were cooled to ? 70°C at 5°C/min and heated to 25°C at 2°C/min in a DSC. Annealing was performed for 2 or 6 h at temperatures, ranging from ? 50 to ? 20°C. Experiments under similar conditions, on select compositions, were also performed in a powder X-ray diffractometer. Two endotherms, observed during heating of a frozen PEG solution (10% w/v), were attributed to PEG–ice eutectic melting and ice melting, and were confirmed by XRD. At higher PEG concentrations (> 37.5% w/w), only the endotherm attributed to the PEG–ice eutectic melting was observed. Inclusion of sucrose decreased both PEG–ice melting and ice melting temperatures. In unannealed systems with a fixed sucrose concentration (10% w/v), the PEG–ice melting event was not observed at PEG concentration < 5% w/v. Annealing for 2–6 h facilitated PEG crystallization. In unannealed systems with a fixed PEG concentration (10% w/v), an increase in the sucrose concentration increased the devitrification but decreased the PEG–ice melting temperature. The PEG–ice melting temperatures obtained by DSC and XRD were in good agreement. In ternary systems at a fixed PEG to sucrose ratio, the T_g^′ as well as the PEG–ice melting temperature were unaffected by the total solute concentration. XRD confirmed the absence of a PEG–sucrose–ice ternary eutectic. When the PEG to sucrose ratio was systematically varied, the PEG–ice and ice melting temperatures decreased with an increase in the sucrose concentration. However, at a fixed PEG to sucrose ratio, the PEG–ice melting temperature, was unaffected by the total solute concentration.     

Comparative in vitro and ex-vivo myelotoxicity of aflatoxins B1 and M1 on haematopoietic progenitors (BFU-E,CFU-E,and CFU-GM): Species-related susceptibility

Haemato- and myelotoxicity are adverse effects caused by mycotoxins. Due to the relevance of aflatoxins to human health, the present study, employing CFU-GM-, BFU-E- and CFU-E-clonogenic assays, aimed at (i) comparing, in vitro, the sensitivity of human vs. murine haematopoietic progenitors to AFB1 and AFM1 (0.001–50 μg/ml), (ii) assessing whether a single AFB1 in vivo treatment (0.3–3 mg/kg b.w.) alters the ability of murine bone marrow cells to form myeloid and erythroid colonies, and (iii) comparing the in vitro with the in vitro ex-vivo data.We demonstrated (i) species-related sensitivity to AFB1, showing higher susceptibility of human myeloid and erythroid progenitors (IC₅₀ values: about 4 times lower in human than in murine cells), (ii) higher sensitivity of CFU-GM and BFU-E colonies, both more markedly affected, particularly by AFB1 (IC₅₀: 2.45 ± 1.08 and 1.82 ± 0.8 μM for humans, and 11.08 ± 2.92 and 1.81 ± 0.20 μM for mice, respectively), than the mature CFU-E (AFB1 IC₅₀: 12.58 ± 5.4 and 40.27 ± 6.05 μM), irrespectively of animal species, (iii) regarding AFM1, a species- and lineage-related susceptibility similar to that observed for AFB1 and (iv) lack of effects after AFB1 in vivo treatment on the proliferation of haematopoietic colonies.     

Pulmonary delivery of pyrazinamide-loaded large porous particles

We have improved the aerodynamic properties of pyrazinamide loaded large porous particles (PZA-LPPs) designed for pulmonary delivery. To overcome the segregation of the different components occurring during the spray drying process and to obtain homogeneous LPPs, spray drying parameters were modified to decrease the drying speed. As a result, good aerodynamic properties for lung delivery were obtained with a fine particle fraction (FPF) of 40.1 ± 1.0%, an alveolar fraction (AF) of 29.6 ± 3.1%, a mass median aerodynamic diameter (MMAD_aer) of 4.1 ± 0.2 μm and a geometric standard deviation (GSD) of 2.16 ± 0.16. Plasma and epithelial lining fluid (ELF) concentrations of pyrazinamide were evaluated after intratracheal insufflation of PZA-LPPs (4.22 mg kg⁻¹) into rats and compared to intravenous administration (iv) of a pyrazinamide solution (5.82 mg kg⁻¹). The in vivo pharmacokinetic evaluation of PZA-LPPs in rats reveals that intratracheal insufflation of PZA-LPPs leads to a rapid absorption in plasma with an absolute bioavailability of 66%. This proves that PZA-LPPs dissolve fast upon deposition and that PZA crosses efficiently the lung barrier to reach the systemic circulation. PZA concentrations were 1.28-fold higher in ELF after intratracheal administration than after iv administration and the ratio of ELF concentrations over plasma concentrations was 2-fold greater. Although these improvements are moderate, lung delivery of PZA appears an interesting alternative to oral delivery of the molecule and should now be tested in an infected animal model to evaluate its efficacy against Mycobacterium tuberculosis.     

GABAA receptor modulation by piperine and a non-TRPV1 activating derivative

The action of piperine (the pungent component of pepper) and its derivative SCT-66 ((2E,4E)-5-(1,3-benzodioxol-5-yl))-N,N-diisobutyl-2,4-pentadienamide) on different gamma-aminobutyric acid (GABA) type A (GABA_A) receptors, transient-receptor-potential-vanilloid-1 (TRPV1) receptors and behavioural effects were investigated.GABA_A receptor subtypes and TRPV1 receptors were expressed in Xenopus laevis oocytes. Modulation of GABA-induced chloride currents (I_GABA) by piperine and SCT-66 and activation of TRPV1 was studied using the two-microelectrode-voltage-clamp technique and fast perfusion. Their effects on explorative behaviour, thermoregulation and seizure threshold were analysed in mice. Piperine acted with similar potency on all GABA_A receptor subtypes (EC₅₀ range: 42.8 ± 7.6 μM (α₂β₂)–59.6 ± 12.3 μM (α₃β₂)). I_GABA modulation by piperine did not require the presence of a γ_2S-subunit, suggesting a binding site involving only α and β subunits. I_GABA activation was slightly more efficacious on receptors formed from β_2/3 subunits (maximal I_GABA stimulation through α₁β₃ receptors: 332 ± 64% and α₁β₂: 271 ± 36% vs. α₁β₁: 171 ± 22%, p < 0.05) and α₃-subunits (α₃β₂: 375 ± 51% vs. α₅β₂:136 ± 22%, p < 0.05). Replacing the piperidine ring by a N,N-diisobutyl residue (SCT-66) prevents interactions with TRPV1 and simultaneously increases the potency and efficiency of GABA_A receptor modulation. SCT-66 displayed greater efficacy on GABA_A receptors than piperine, with different subunit-dependence. Both compounds induced anxiolytic, anticonvulsant effects and reduced locomotor activity; however, SCT-66 induced stronger anxiolysis without decreasing body temperature and without the proconvulsive effects of TRPV1 activation and thus may serve as a scaffold for the development of novel GABA_A receptor modulators.     

Delivery of Nerve Growth Factor to Brain Via Intranasal Administration and Enhancement of Brain Uptake

The main objective of the study was to investigate the efficacy of chitosan to facilitate brain bioavailability of intranasally administered nerve growth factor (NGF). In vitro permeability studies and electrical resistance studies were carried out across the bovine olfactory epithelium using Franz diffusion cells. The bioavailability of intranasally administered NGF in rat hippocampus was determined by carrying out brain microdialysis in Sprague–Dawley rats. The in vitro permeation flux across the olfactory epithelium of NGF solution without chitosan (control) was found to be 0.37 ± 0.06 ng/cm²/h. In presence of increasing concentration of chitosan (0.1%, 0.25%, and 0.5%, w/v) the permeation flux of NGF was found to be 2.01 ± 0.12, 3.88 ± 0.19, and 4.12 ± 0.21 ng/cm²/h respectively. Trans-olfactory epithelial electrical resistance decreased ～34.50 ± 4.06% in presence of 0.25% (w/v) chitosan. The C_max in rats administered with 0.25% (w/v) chitosan and NGF was 1008.62 ± 130.02 pg/mL, which was significantly higher than that for rats administered with NGF only 97.38 ± 10.66 pg/mL. There was ～14-fold increase in the bioavailability of intranasally administered NGF with chitosan than without chitosan. Chitosan can enhance the brain bioavailability of intranasally administered NGF. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3640–3646, 2009     

Influence of Non-Water-Soluble Placebo Pellets of Different Sizes on the Characteristics of Orally Disintegrating Tablets Manufactured by Freeze-Drying

The present study describes the development of an orally disintegrating tablet containing a non-water-soluble drug delivery system. A model system was applied to evaluate the effect of different-sized particles on tablet characteristics. Cellets were incorporated into tablets prepared by freeze-drying from a 100 mg/mL mannitol or sucrose solution. Particle size distributions were 200–355 μm for Cellets 200 (C200) and 500–710 μm for Cellets 500 (C500). An examination of the tablets revealed that the particles could not be sufficiently embedded in mannitol because of its crystalline nature. The tablet hardness was also inadequate. In contrast, the hardness of sucrose tablets was increased by the addition of Cellets 500. Therefore, the sucrose-based formulation was studied further. Binders [hydroxyethylstarch, sodium alginate, methylcellulose (MC), and gelatin] were added in different concentrations, and tablets were made either with or without placebo pellets. A positive effect of the Cellets on the hardness of tablets was identified. Furthermore, disintegration time could be clearly reduced by Cellets for tablets made from 100 mg/mL sucrose with addition of 10 mg/mL MC, 20 or 40 mg/mL gelatin. The freeze-dried tablet index revealed that the formulations of sucrose with 50 mg/mL hydroxyethylstarch or 20 mg/mL gelatin were particularly advantageous.     

Inhibitory vs. protective effects of N-acetyl-l-cysteine (NAC) on the electromechanical properties of the spontaneously beating atria of the frog (Rana ridibunda): An ex vivo study

The results of this study have shown that N-acetyl-l-cysteine (NAC), a compound used for protection of tissues or cell cultures against the deleterious effects of various environmental pollutants, has certain unusual effects on the contraction of the spontaneously beating atria of the frog isolated in saline (ex vivo): (1) NAC, 6.0 and 10.0 mM, eliminated, in a concentration-dependent manner, the contractile properties of the atria (force and frequency) within minutes, without affecting its electrical properties; (2) the IC₅₀ of NAC for the force was 5.09 ± 1.01 mM (n = 6) [4.98–5.19 mM, 95% confidence interval (CI)], significantly lower than the IC₅₀ for the frequency, 6.15 ± 1.01 mM, (6.02–6.29 mM, 95% CI), indicating that working atria cells are more sensitive to NAC than autorhythmic cells. The no-observed-effect concentration (NOEC) was 1–2 mM; (3) the pattern of NAC-induced inhibition of electromechanical activity was similar to that of verapamil, an indication that NAC possibly affects L-type voltage-gated calcium channels; (4) NAC at 2 mM protected against cadmium-induced inhibition of atria contraction. The IC₅₀ for cadmium was 17.9 ± 1.1 μM (n = 6) (16.9–19.0 μM, 95% CI), while in the presence of 2 mM NAC, it became 123.3 ± 1.0 μΜ (n = 6) (114.8–132.4 μM, 95% CI). The same concentration of NAC failed to exert any protective effects against rotenone (5 μM)-induced inhibition of atria contraction. The protective effects of NAC are probably due to chelation of cadmium, rather than scavenging of oxidants.     

The direct effects of streptozotocin and alloxan on contractile function in rat heart

Streptozotocin (STZ) and alloxan (ALX) are widely used to induce diabetes mellitus in experimental animals. The direct effects of STZ and ALX on the amplitude and time course of ventricular myocyte shortening and on cardiac action potentials were investigated. STZ and ALX (10^?5 M) were dissolved in normal Tyrode (NT), maintained at pH 7.4 and 37 °C and stored for either 15 or 60–120 min. Both compounds reduced the amplitude of myocyte shortening. Compared to NT the amplitude of shortening was 34.7 ± 5.0% and 35.2 ± 6.8% with STZ and 41.0 ± 5.5% and 37.3 ± 5.7% with ALX stored for 15 and 60–120 min, respectively. During a 10 min NT washout STZ myocytes recovered to 56.2 ± 8.3% and 60.5 ± 8.2% and ALX myocytes recovered to 88.9 ± 10.0% and 83.7 ± 9.9% after storage of compounds for 15 and 60–120 min, respectively. Perfusion of the whole heart with ALX induced bradycardia but had no effects on the duration of action potential repolarization at 50% and 70% from peak action potential. The negative inotropic effects of STZ and ALX were not altered by storage. The results suggest that some of the effects on heart reported in STZ- and ALX-induced diabetes may be partly attributed to direct action of these compounds.     

Through-Vial Impedance Spectroscopy of the Mechanisms of Annealing in the Freeze-Drying of Maltodextrin: The Impact of Annealing Hold Time and Temperature on the Primary Drying Rate

The study aims to investigate the impact of annealing hold time and temperature on the primary drying rate/duration of a 10% (w/v) solution of maltodextrin with an emphasis on how the mechanisms of annealing might be understood from the in-vial measurements of the ice crystal growth and the glass transition. The electrical impedance of the solution within a modified glass vial was recorded between 10 and 10⁶ Hz during freeze-drying cycles with varying annealing hold times (1–5 h) and temperatures. Primary drying times decreased by 7%, 27% and 34% (1.1, 4.3 and 5.5 h) with the inclusion of an annealing step at temperatures of –15 °C, –10 °C and –5 °C, respectively. The glass transition was recorded at approximately –16 °C during the re-heating and re-cooling steps, which is close to the glass transition (T_g′) reported for 10% (w/v) maltodextrin and therefore indicates that a maximum freeze concentration (~ 86%, w/w, from the Gordon–Taylor equation) was achieved during first freezing, with no further ice being formed on annealing. This observation, coupled to the decrease in electrical resistance that was observed during the annealing hold time, suggests that the reduction in the drying time was because of improved connectivity of ice crystals because of Ostwald ripening rather than devitrification. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:1799–1810, 2014