- Enhanced transdermal delivery by combined application of dissolving microneedle patch on serum-treated skin. [Journal Article]
- MPMol Pharm 2017 Apr 27
- Dissolving microneedle (DMN), a transdermal drug delivery system in which drugs are encapsulated in a biodegradable polymeric micro-structure, is designed to dissolve after skin penetration and relea...
Dissolving microneedle (DMN), a transdermal drug delivery system in which drugs are encapsulated in a biodegradable polymeric micro-structure, is designed to dissolve after skin penetration and release the encapsulated drugs into the body. However, due to limited loading capacity of drugs within micro-sized structures, only small dosage can be delivered which are often insufficient for patients. We propose a novel DMN application that combines topical and DMN application simultaneously to improve skin permeation efficiency. Drugs in pre-treated topical formulation and encapsulated drugs in DMN patch are delivered into the skin through micro-channels created by DMN application; thus, greatly increasing the delivered dose. We used 4-n-butylresorcinol to treat human hyper-pigmentation, and found that sequential application of serum formulation and DMNs were successful. In skin distribution experiments using Alexa Fluor 488 and 568 dyes as model drugs, we confirmed that the pre-treated serum formulation was delivered into the skin through micro-channels created by the DMNs. In vitro skin permeation and retention experiments confirmed that this novel combined application delivered more 4-n-butylresorcinol into the skin than traditional DMN-only and serum-only applications. Moreover, this combined application showed a higher efficacy in reducing patients' melanin index and hyper-pigmented regions, compared with the serum-only application. As combined application of DMNs on serum-treated skin can overcome both dose limitations and safety concerns, this novel approach can advance developments in transdermal drug delivery.
- "Liquid Crystalline Nanoparticles": Rationally designed vehicle to improve stability and therapeutic efficacy of insulin following oral administration. [Journal Article]
- MPMol Pharm 2017 Apr 27
- In the present report we investigate the feasibility of liquid crystalline nanoparticles (LCNPs) to improve the stability and therapeutic efficacy of insulin following oral administration. Compatibil...
In the present report we investigate the feasibility of liquid crystalline nanoparticles (LCNPs) to improve the stability and therapeutic efficacy of insulin following oral administration. Compatibility studies of different formulation ingredients with insulin and extensive optimization of different process variables resulted into the formation of LCNPs with particle size of 245.50 ± 6.36 nm, PDI 0.220 ± 0.042, zeta potential -18.30 ± 1.27 mV with an entrapment efficiency of 44.17 ± 1.47%. Mannitol (5% w/v) was identified as suitable cryoprotectant to produce freeze dried LCNPs without affecting the critical quality attributes of the LCNPs. LCNPs demonstrated excellent stability in simulated biological fluids by simultaneously retaining the chemical and conformational stability of the insulin entrapped within the LCNPs. A sustained release of insulin was observed for up to 24 h in PBS (pH 7.4). Developed LCNPs demonstrated remarkably higher caco-2 cell uptake in comparison with free Insulin-FITC and more than double the cumulative hypoglycemia in comparison with subcutaneously administered insulin solution in diabetic rats. Data in hand suggests that the proposed formulation strategy can be exploited for improving the therapeutic efficacy of the biomacromolecules like insulin.
- High Serum Stability of Collagen Hybridizing Peptides and Their Fluorophore Conjugates. [Journal Article]
- MPMol Pharm 2017 Apr 26
- Collagen hybridizing peptides (CHPs) have a great potential for use in targeted drug delivery, diagnostics, and regenerative medicine due to their ability to specifically bind to denatured collagens ...
Collagen hybridizing peptides (CHPs) have a great potential for use in targeted drug delivery, diagnostics, and regenerative medicine due to their ability to specifically bind to denatured collagens associated with many pathologic conditions. Since peptides generally suffer from poor enzymatic stability resulting in rapid degradation and elimination in vivo, CHP's serum stability is a critical parameter that may dictate its pharmacokinetic behavior. Here, we report the serum stability of a series of monomeric CHP derivatives and establish how peptide length, amino acid composition, terminal modification, and linker chemistry influence their availability in serum. We show that monomeric CHPs comprised of the collagen-like Gly-Pro-Hyp motif are resistant to common serum proteinases and that their stability can be further increased by simple N-terminal labeling which negates CHP's susceptibility to proline-specific exopeptidases. When fluorescent dyes are conjugated to CHP via maleimide-thiol reaction, the dye can transfer from CHP onto serum proteins (e.g. albumin) resulting in an unexpected drop in signal during serum stability assays and off-target accumulation during in vivo tests. This work is the crucial first step toward understanding the pharmacokinetic behavior of CHPs which can facilitate the development of CHP-based theranostics.
- Superior plasticity and tabletability of theophylline monohydrate. [Journal Article]
- MPMol Pharm 2017 Apr 26
- A theophylline monohydrate (THm) powder, with particle size and shape substantially similar to a theophylline anhydrate powder, was prepared by vapor mediated phase conversion. The elimination of pos...
A theophylline monohydrate (THm) powder, with particle size and shape substantially similar to a theophylline anhydrate powder, was prepared by vapor mediated phase conversion. The elimination of possible contributions by particle size and shape to tableting properties made it possible to unambiguously identify the role of bonding area and bonding strength on powder tableting performance. It was also shown that accurate true density is essential for correct analysis and understanding of tableting behavior of THm. Experimental evidence revealed surprisingly high plasticity of THm. This is explained by its unique ladder-like structure, where rigid molecular dimers (rungs) weakly connect to more rigid water chains (rails). The low energy barrier for moving rigid dimers down the rigid water chain enables facile propagation of dislocations in THm crystals when subjected to an external stress.
- Sulfotransferases and Breast Cancer Resistance Protein Determine the Disposition of Calycosin in Vitro and in Vivo. [Journal Article]
- MPMol Pharm 2017 Apr 26
- Sulfation is a key process of drugs disposition that generally regulates the drug effectiveness and toxicity. Calycosin derived from the dry root extract of Radix Astragali exhibits a variety of biol...
Sulfation is a key process of drugs disposition that generally regulates the drug effectiveness and toxicity. Calycosin derived from the dry root extract of Radix Astragali exhibits a variety of biological effects that easily undergo extensive phase II metabolism. However, the sulfation pathway of calycosin lacks information. We investigated the disposition mechanisms of calycosin sulfate in vitro and in vivo. We characterized the sulfation metabolism and excretion of calycosin using bi-directional transport studies. We confirmed that sulfate conjugate is breast cancer resistance protein (BCRP) substrate using the intestinal perfusion model and pharmacokinetics studies in Bcrp1-/- mice. Results showed that calycosin is rapidly and extensively metabolized to calycosin-3'-sulfate (C-3'-S) in the intestine and liver. The overexpressed of BCRP led to a substantial increase (approximately 14-fold, p < 0.01) of excreted C-3'-S in the BCRP overexpressed Mardin-Darby canine kidney II (MDCK II/BCRP) cells. The chemical inhibition of BCRP caused reduction (about 2-fold, p < 0.01) in C-3'-S apical excretion. Furthermore, in intestinal perfusion studies, the deletion of Bcrp1 significantly decreased C-3'-S excretion in the small intestine (82.6%-90.6%, p < 0.01) and colon (97.6%-98.2%, p < 0.01). In contrast, plasma level of C-3'-S was increased to 40-fold (p < 0.01) in Bcrp1-/- mice. In conclusion, calycosin undergoes an extensive sulfation metabolism and BCRP is a critical determinant to the disposition of C-3'-S.
- Facile Preparation of Drug-Loaded Tristearin Encapsulated Superparamagnetic Iron Oxide Nanoparticles using Coaxial Electrospray Processing. [Journal Article]
- MPMol Pharm 2017 Apr 26
- Naturally occurring polymers are promising biocompatible materials that have many applications for emerging therapies, drug delivery systems and diagnostic agents. The handling and processing of such...
Naturally occurring polymers are promising biocompatible materials that have many applications for emerging therapies, drug delivery systems and diagnostic agents. The handling and processing of such materials still constitutes a major challenge which can limit the full exploitation of their properties. This study explores an ambient environment processing technique: coaxial electrospray (CO-ES) to encapsulate genistein (an isoflavonoid and model drug), superparamagnetic iron oxide nanoparticles (SPIONs, 10-15 nm) and a fluorophore (BODIPY) into a layered (triglyceride tristearin shell) particulate system, with a view to constructing a theranostic agent. Mode mapping of CO-ES led to an optimized atomization engineering window for stable jetting, leading to encapsulation of SPIONs within particles of diameter 0.65 - 1.2 µm and drug encapsulation efficiencies of around 92%. Electron Microscopy was used to image the encapsulated SPIONs and confirm core-shell triglyceride encapsulation in addition to further physicochemical characterization (AFM, FTIR, DSC and TGA). Cell viability assays (MTT, HeLa cells) were used to determine optimal SPIONs loaded particles (~1 mg/mL) while in vitro release profile experiments (PBS, pH = 7.4) demonstrate a triphasic release profile. Further cell studies confirmed cell uptake and internalization at selected time points (t = 1, 2 and 4 h). The results suggest potential for using the CO-ES technique as an efficient way to encapsulate SPIONs together with sensitive drugs for the development of multi-modal particles that have potential application for combined imaging and therapy.
- Identification and characterization of a secondary sodium-binding site and the main selectivity determinants in the human Concentrative Nucleoside Transporter 3. [Journal Article]
- MPMol Pharm 2017 Apr 25
- The family of concentrative Na(+):nucleoside cotransporters in humans is constituted by three subtypes, namely hCNT1, hCNT2 and hCNT3. Besides their different nucleoside selectivity, hCNT1 and hCNT2 ...
The family of concentrative Na(+):nucleoside cotransporters in humans is constituted by three subtypes, namely hCNT1, hCNT2 and hCNT3. Besides their different nucleoside selectivity, hCNT1 and hCNT2 have a Na(+):nucleoside stoichiometry of 1:1, while for hCNT3 it is of 2:1. This distinct stoichiometry of subtype 3 might hint the existence of a secondary sodium-binding site that is not present in the other two subtypes, but to date their three-dimensional structures remain unknown and the residues implicated in Na(+) binding are unclear. In this work, we have identified and characterized the Na(+) binding sites of hCNT3 by combining molecular modelling and mutagenesis studies. A model of the transporter was obtained by homology modelling and key residues of two sodium-binding sites were identified and verified with a mutagenesis strategy. The structural model explains the altered sodium-binding properties of the hCNT3C602R polymorphic variant and supports previously generated data identifying the determinant residues of nucleoside selectivity, paving the way to understand how drugs can target this plasma membrane transporter.
- Development of a Biorelevant, Material-sparing Membrane Flux Test for Rapid Screening of Bioavailability-enhancing Drug Product Formulations. [Journal Article]
- MPMol Pharm 2017 Apr 25
- Bioavailability-enhancing formulations are often used to overcome challenges of poor gastrointestinal solubility for drug substances developed for oral administration. Conventional in vitro dissoluti...
Bioavailability-enhancing formulations are often used to overcome challenges of poor gastrointestinal solubility for drug substances developed for oral administration. Conventional in vitro dissolution tests often do not properly compare such formulations due to the many different drug species that may exist in solution. To overcome these limitations, we have designed a practical in vitro membrane flux test, requiring minimal active pharmaceutical ingredient (API) and capable of rapidly screening many drug product intermediates. This test can be used to quickly compare performance of bioavailability-enhancing formulations with fundamental knowledge of the rate-limiting step(s) to membrane flux. Using this system, we demonstrate that the flux of amorphous itraconazole (logD = 5.7) is limited by aqueous boundary layer (ABL) diffusion and can be increased by adding drug-solubilizing micelles or drug-rich colloids. Conversely, the flux of crystalline ketoconazole at pH 5 (logD = 2.2) is membrane-limited and adding solubilizing micelles does not increase flux. Under certain circumstances, the flux of ketoconazole may also be limited by dissolution rate. These cases highlight how a well-designed in vitro assay can provide critical insight for oral formulation development. Knowing whether flux is limited by membrane diffusion, ABL diffusion, or dissolution rate can help drive formulation development decisions. It may also be useful in predicting in vivo performance, dose linearity, food effects, and regional dependent flux along the length of the gastrointestinal tract.
- Alleviation of Multiple Asthmatic Pathologic Features with Orally Available and Subtype Selective GABAA Receptor Modulators. [Journal Article]
- MPMol Pharm 2017 Apr 25
- We describe pharmacokinetic and pharmacodynamic properties of two novel oral drug candidates for asthma. Phenolic α4β3γ2 GABAAR selective compound 1 and acidic α5β3γ2 selective GABAAR positive allost...
We describe pharmacokinetic and pharmacodynamic properties of two novel oral drug candidates for asthma. Phenolic α4β3γ2 GABAAR selective compound 1 and acidic α5β3γ2 selective GABAAR positive allosteric modulator compound 2 relaxed airway smooth muscle ex vivo and attenuated airway hyperresponsiveness (AHR) in a murine model of asthma. Importantly, compound 2 relaxed acetylcholine contracted human tracheal airway smooth muscle strips. Oral treatment of compound 1 and 2 decreased eosinophils in bronchoalveolar lavage fluid in ovalbumin sensitized and challenged mice, thus exhibiting anti-inflammatory properties. Additionally, compound 1 reduced the number of lung CD4+ T lymphocytes and directly modulated their transmembrane currents by acting on GABAARs. Excellent pharmacokinetic properties were observed, including long plasma half-life (up to 15 hours), oral availability, and extremely low brain distribution. In conclusion, we report the selective targeting of GABAARs expressed outside the brain and demonstrate reduction of AHR and airway inflammation with two novel orally available GABAAR ligands.
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- Brain uptake of bioactive flavones in Scutellariae Radix and its relationship to anxiolytic effect in mice. [Journal Article]
- MPMol Pharm 2017 Apr 20
- Scutellariae Radix (SR) and its bioactive flavones elicit a variety of effects in the brain. However, the brain uptake of individual SR flavones and its relationship to the elicited effects after SR ...
Scutellariae Radix (SR) and its bioactive flavones elicit a variety of effects in the brain. However, the brain uptake of individual SR flavones and its relationship to the elicited effects after SR administration remain unknown. Moreover, previous studies seldom measured pharmacokinetic and pharmacodynamic outcomes simultaneously. In the current study, the brain uptake of six major SR flavones and the anxiolytic behavior following oral administration of a SR extract at two clinically relevant doses (600 and 1200 mg/kg twice daily) were simultaneously investigated in mice (n=18 per group). Brain and plasma concentrations of the flavones were measured by LC-MS/MS, while the anxiolytic effect was evaluated using the elevated plus-maze. To further investigate the mechanism behind the differential brain uptake of the six SR flavones, these flavones were separately administered to mice at an equivalent molar oral dose (n=6). The brain tissue bindings of the SR flavones were also measured with the in vitro brain slice method. Our results indicated that all the six SR flavones including three aglycones (baicalein, wogonin and oroxylin A) and three glucuronides (baicalin, wogonoside and oroxyloside) could pass through the blood-brain-barrier, with brain concentrations ranging from 7.9 to 224.0 pmol/g. It provided novel evidence that oroxylin A had the highest brain uptake among the six SR flavones regardless of its limited content in SR extract, in which 3.6-3.9% of the administered oroxylin A dose was present in the brain 6 h post-dosing and with a brain-to-plasma ratio of 0.42-0.46. Although SR extract contains flavones that are positive modulators of the benzodiazepine binding site of GABAA receptors (baicalein, wogonin and baicalin), our behavioral study for the first time indicated that SR extract (a mixture of six flavones) did not elicit significant anxiolytic effect at the studied doses. Oroxylin A also demonstrated the highest brain uptake when the six flavones were separately administered to mice, and the highest affinity to brain tissues in the in vitro tissue binding assay. The high brain uptake of oroxylin A, a GABAA antagonist which had been reported to antagonize diazepam-induced anxiolytic effect, might have suppressed the anxiolytic effects of the other flavones and account for the lack of overall anxiolytic effect of SR extract. The current study illustrates the importance of monitoring pharmacokinetics in a behavioral study, particularly for herbal medicines which consist of multiple components that might have different or even opposite pharmacological effects on the same target.