Chitosan-poloxamer-based thermosensitive hydrogels containing zinc gluconate/recombinant human epidermal growth factor benefit for antibacterial and wound healing

Chitosan/poloxamer-based thermosensitive hydrogels containing zinc gluconate/recombinant human epidermal growth factor (ZnG/rhEGF@Chit/Polo) were developed as a convenient, safe and effective dressing for skin wound treatment. Their fabrication procedure and characterization were reported, and their morphology was examined by a scanning electron microscope. Antibacterial and biofilms activities were evaluated by in vitro tests to reveal the inhibitory effects and scavenging activity on the biofilms of Staphylococcus aureus and Pseudomonas aeruginosa. ZnG/rhEGF@Chit/Polo was also investigated as a potential therapeutic agent for wound healing therapy. In vivo wound healing studies on rats for 21 days proves that ZnG/rhEGF@Chit/Polo supplements the requisite Zn²⁺ and rhEGF for wound healing to promote the vascular remodeling and collagen deposition, facilitate fibrogenesis, and reduce the level of interleukin 6 for wound basement repair, and thus is a good wound therapy.

Comparative study of oral and intranasal puerarin for prevention of brain injury induced by acute high-altitude hypoxia

Human activities in the areas of high altitude have increased significantly recently. Brain is highly sensitive to changing of oxygen pressure due to high altitude, and this physiological response may lead to serious brain injury, such as learning and memory disabilities. Puerarin is a phytoestrogen with many pharmacological activities, such as treatment of neurological disorders. However, most of current drugs can not easily enter brain through the blood-brain barrier (BBB). The nose-to-brain route can bypass BBB for brain-targeting. Here, thermosensitive in situ hydrogels (TISGs) of puerarin were prepared with poloxamers 407, poloxamers 188 and propylene glycol to improve bioavailability and brain targeting. In vitro drug release in simulated nasal fluids, rheological properties and cilia toxicity of puerarin TISGs were explored. The pharmacodynamics and pharmacokinetics of puerarin by intranasal (i.n.) and oral (p.o.) administrations were also evaluated. The viscosity of puerarin TISGs tended to increase obviously with increased temperature. The puerarin release profile and transmucosal process of puerarin TISGs could be described with the first-order kinetics equation, depending on drug diffusion. The cilia toxicity of puerarin TISGs was not obvious. Rat models of hypobarism/hypoxia-induced brain injury were established with a hypobaric simulation chamber. Morris water maze and open filed tests indicated that puerarin TISGs improved the spatial memory and spontaneous exploratory behavior of the rats suffering from hypoxia-induced brain injury. Furthermore, puerarin TISGs decreased the level of oxidative stress cytokines (malondialdehyde (MDA) and glutathione (GSH)) in the peripheral circulation, alleviated the cerebral histological lesions, and relieved the expression of hypoxia-inducible factor-1α (HIF-1α). Intranasal puerarin TISGs were absorbed quickly with a shorter T_max (10.0 ± 5.7 min) compared to that of oral puerarin (36 ± 13.4 min). In addition, the relative bioavailability of i.n. puerarin TISGs was high to 300% compared to oral administration of puerarin. The area under the curve (AUC) of brain after i.n. administration of puerarin TISGs was 954.5 ± 335.1 h.ng/mL, while no puerarin was detected in the brain after oral administration. Therefore, i.n. puerarin TISGs led to excellent brain targeting effect. Puerarin TISGs are an effective neuroprotector formulation for prevention of brain injury induced by acute high-altitude hypoxia.

Nasal timosaponin BII dually sensitive in situ hydrogels for the prevention of Alzheimer's disease induced by lipopolysaccharides

Alzheimer's disease (AD) is a common and severe brain disease with a high mortality among the elders, but no highly efficient medications are currently available. For example, timosaponin BII, an efficient anti-AD agent, has low oral bioavailability. Here, timosaponin BII was formulated in a temperature/ion-sensitive in situ hydrogel (ISG) that was well transformed into gels in the nasal environment. Timosaponin BII protected the PC12 cells injured by lipopolysaccharides (LPS) by decreasing TNF-α and IL-1β and stabilizing F-actin. Timosaponin BII ISGs were intranasally administered to the mice every day for 38 days. On Day 36, LPS was injected to the mice to establish an AD model. Morris water maze experiments showed that the number of the animals that were able to cross the platform returned to normal and the total distance over which the animals moved in the open field also increased, which demonstrated that the spatial memory and spontaneous behavior were improved after treatment compared to the model. Moreover, an AD improver, inducible nitric oxide synthase (iNOS) in the brain, was reduced after treatment. High brain targeting effect of timosaponin BII ISGs was confirmed by in vivo fluorescence imaging. The nasal timosaponin BII dually sensitive ISGs can serve as a promising medication for local prevention of AD.

Nanostructured lipid carriers used for oral delivery of oridonin: an effect of ligand modification on absorption

Oridonin (Ori) is a natural compound with notable anti-inflammation and anti-cancer activities. However, therapeutic use of this compound is limited by its poor solubility and low bioavailability. Here a novel biotin-modified nanostructured lipid carrier (NLC) was developed to enhance the bioavailability of Ori. The effect of ligand (biotin) modification on oral absorption of Ori encapsulated in NLCs was also explored. Ori-loaded NLCs (Ori-NLCs) were prepared by the melt dispersion-high pressure homogenization method. Biotin modification of Ori-NLCs was achieved by EDC and NHS in aqueous phase. The obtained biotin-decorated Ori-NLCs (Bio-Ori-NLCs) were 144.9nm in size with an entrapment efficiency of 49.54% and a drug load of 4.81%. Oral bioavailability was enhanced by use of Bio-Ori-NLCs with a relative bioavailability of 171.01%, while the value of non-modified Ori-NLCs was improved to 143.48%. Intestinal perfusion showed that Ori solution unexpectedly exhibited a moderate permeability, indicating that permeability was not a limiting factor of Ori absorption. Ori could be rapidly metabolized that was the main cause of low bioavailability. However, there was a difference in the enhancement of bioavailability between Bio-Ori-NLCs and conventional NLCs. Although severe lipolyses happened both on Bio-Ori-NLCs and non-modified NLCs, the performance of Bio-Ori-NLCs in the bioavailability improvement was more significant. Overall, Bio-Ori-NLCs can further promote the oral absorption of Ori by a ligand-mediated active transport. It may be a promising carrier for the oral delivery of Ori.

Effects of stabilizing agents on the development of myricetin nanosuspension and its characterization: an in vitro and in vivo evaluation

Although myricetin has various pharmacological applications, it shows low oral bioavailability (<10%) in rats due to its poor aqueous solubility. To overcome this issue, myricetin nanosuspensions were developed and the effects of stabilizers were investigated. Based on the particle size and zeta potential, stabilizers soya lecithin, TPGS, HP-β-CD, and/or a combination thereof were used. The prepared nanosuspensions were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray powder diffraction (XRD). The resulting myricetin nanosuspensions contained particles in the size range of 300-500 nm and were physically stable. Myricetin was partially transformed from crystalline to amorphous forms in the presence of different excipients after the nanosizing process. The solubility and in vitro dissolution of all myricetin nanosuspensions were greatly increased compared with those of the myricetin powder. Consequently, the relative bioavailability in rats were 2.44, 3.57, 1.61, and 2.96 for nanosuspensions stabilized with TPGS, soya lecithin, soya lecithin+TPGS, and HP-β-CD+TPGS, respectively, relative to that of the coarse myricetin. This research demonstrated that nanosuspension is a promising strategy for delivering poor water-soluble drugs such as myricetin and that stabilizers played a critical role in the formulation design of myricetin nanosuspensions.