Ligand design for human acetylcholinesterase and nicotinic acetylcholine receptors, extending beyond the conventional and canonical.

We detail here distinctive departures from lead classical cholinesterase re-activators, the pyridinium aldoximes, to achieve rapid CNS penetration and reactivation of AChE in the CNS (brain and spinal cord). Such reactivation is consistent with these non-canonical re-activators enhancing survival parameters in both mice and macaques following exposure to organophosphates. Thus, the ideal cholinesterase re-activator should show minimal toxicity, limited inhibitory activity in the absence of an organophosphate, and rapid CNS penetration, in addition to its nucleophilic potential at the target, the conjugated AChE active center. These are structural properties directed to reactivity profiles at the conjugated AChE active center, reinforced by the pharmacokinetic and tissue disposition properties of the re-activator leads. In the case of nicotinic acetylcholine receptor (nAChR) agonists and antagonists, with the many existing receptor subtypes in mammals, we prioritize subtype selectivity in their design. In contrast to nicotine and its analogues that react with panoply of AChR subtypes, the substituted di-2-picolyl amine pyrimidines possess distinctive ionization characteristics reflecting in selectivity for the orthosteric site at the α7 subtypes of receptor. Here, entry to the CNS should be prioritized for the therapeutic objectives of the nicotinic agent influencing aberrant CNS activity in development or in the sequence of CNS ageing (longevity) in mammals, along with general peripheral activities controlling inflammation.

Enhancing Target Tissue Levels and Diminishing Plasma Clearance of Ionizing Zwitterionic Antidotes in Organophosphate Exposures.

Inhibition of acetylcholinesterase (AChE) by certain organophosphates (OPs) can be life-threatening and requires reactivating antidote accessibility to the peripheral and central nervous systems to reverse symptoms and enhance survival parameters. In considering dosing requirements for oxime antidotes in OP exposures that inactivate AChE, clearance of proton ionizable, zwitterionic antidotes is rapid and proceeds with largely the parent antidotal compound being cleared by renal transporters. Such transporters may also control disposition between target tissues and plasma as well as overall elimination from the body. An ideal small-molecule antidote should access and be retained in primary target tissues-central nervous system (brain), skeletal muscle, and peripheral autonomic sites-for sufficient periods to reactivate AChE and prevent acute toxicity. We show here that we can markedly prolong the antidotal activity of zwitterionic antidotes by inhibiting P-glycoprotein (P-gp) transporters in the brain capillary and renal systems. We employ the P-gp inhibitor tariquidar as a reference compound and show that tissue and plasma levels of RS194B, a hydroxyl-imino acetamido alkylamine reactivator, are elevated and that plasma clearances are reduced. To examine the mechanism, identify the transporter, and establish the actions of a transport inhibitor, we compare the pharmacokinetic parameters in a P-glycoprotein knockout mouse strain and see dramatic enhancements of short-term plasma and tissue levels. Hence, repurposed transport inhibitors that are candidate or Food and Drug Administration-approved drugs, should enhance target tissue concentrations of the zwitterionic antidote through inhibition of both renal elimination and brain capillary extrusion. SIGNIFICANCE STATEMENT: We examine renal and brain capillary transporter inhibition as means for lowering dose and frequency of dosing of a blood-brain barrier permanent reactivating antidote, RS194B, an ionizable zwitterion. Through a small molecule, tariquidar, and gene knockout mice, CNS antidote concentrations are enhanced, and total body clearances are concomitantly diminished. RS194B with repurposed transport inhibitors should enhance reactivation of central and peripheral OP-inhibited acetylcholinesterase. Activities at both disposition sites are a desired features for replacing the antidote, pralidoxime, for acute OP exposure.

Development of an In Vitro 3D Model for Investigating Ligamentum Flavum Hypertrophy.

BACKGROUND: Ligamentum flavum hypertrophy (LFH) is among the most crucial factors in degenerative lumbar spinal stenosis, which can cause back pain, lower extremity pain, cauda equina syndrome and neurogenic claudication. The exact pathogenesis of LFH remains elusive despite extensive research. Most in vitro studies investigating LFH have been carried out using conventional two-dimensional (2D) cell cultures, which do not resemble in vivo conditions, as they lack crucial pathophysiological factors found in three-dimensional (3D) LFH tissue, such as enhanced cell proliferation and cell cluster formation. In this study, we generated ligamentum flavum (LF) clusters using spheroid cultures derived from primary LFH tissue. RESULTS: The cultured LF spheroids exhibited good viability and growth on an ultra-low attachment 96-well plate (ULA 96-plate) platform according to live/dead staining. Our results showed that the 100-cell culture continued to grow in size, while the 1000-cell culture maintained its size, and the 5000-cell culture exhibited a decreasing trend in size as the culture time increased; long-term culture was validated for at least 28 days. The LF spheroids also maintained the extracellular matrix (ECM) phenotype, i.e., fibronectin, elastin, and collagen I and III. The 2D culture and 3D culture were further compared by cell cycle and Western blot analyses. Finally, we utilized hematoxylin and eosin (H&E) staining to demonstrate that the 3D spheroids resembled part of the cell arrangement in LF hypertrophic tissue. CONCLUSIONS: The developed LF spheroid model has great potential, as it provides a stable culture platform in a 3D model that can further improve our understanding of the pathogenesis of LFH and has applications in future studies.

Long acting tariquidar loaded stearic acid-modified hydroxyapatite enhances brain penetration and antitumor effect of temozolomide.

Temozolomide (TMZ) is the first line chemotherapy for glioblastoma (GBM) treatment, but the P-glycoprotein (P-gp) expressed in blood-brain barrier (BBB) will pump out TMZ from the brain leading to decreased TMZ concentration. Tariquidar (TQD), a selective and potent P-gp inhibitor, may be suitable for combination therapy to increase concentration of TMZ in brain. Hydroxyapatite (HAP) is a biodegradable material with sustained release characteristics, and stearic acid surface-modified HAP (SA-HAP) can increase hydrophobicity to facilitate TQD loading. TQD-loaded stearic acid surface-modified HAP (SA-HAP-TQD) was prepared with optimal size and high TQD loading efficiency, and in vitro release and cellular uptake of SA-HAP-TQD showed that SA-HAP-TQD were taken up into lysosome and continuously released TQD from macrophages. In vivo studies have found that over 70% of SA-HAP was degraded and 80% of TQD was released from SA-HAP-TQD 28 days after administration. SA-HAP-TQD could increase brain penetration of TMZ, but it would not enhance adverse effects of TMZ in healthy mice. SA-HAP-TQD and TMZ combination had longer median survival than TMZ single therapy in GL261 orthotopic model. These results suggest that SA-HAP-TQD has sustained release characteristics and are potential for improving antitumor effect with TMZ treatment.

BMSC loaded photo-crosslinked hyaluronic acid/collagen hydrogel incorporating FG4592 for enhanced cell proliferation and nucleus pulposus differentiation.

Intervertebral disc degeneration arises from damage or degeneration of the nucleus pulposus (NP). In this study, we developed a photo-crosslinkable hydrogel incorporating FG4592 to support the growth and differentiation of bone-marrow-derived mesenchymal stem cells (BMSC). Initially, hyaluronic acid was modified with tyramine and combined with collagen to introduce riboflavin as a photo-crosslinker. This hydrogel transitioned from liquid to gel upon exposure to blue light in 3 min. The results showed that the hydrogel was biodegradable and had mechanical properties comparable to those of human NP tissues. Scanning electron microscopy after BMSC seeding in the hydrogel revealed an even distribution, and cells adhered to the collagen fibers in the hydrogel with minimal cell mortality. The effect of FG4592 on BMSC proliferation and differentiation was examined, revealing the capability of FG4592 to promote BMSC proliferation and direct differentiation resembling human NP cells. After cultivating BMSCs in the photo-crosslinked hydrogel, there was an upregulation in the expression of glycosaminoglycans, aggrecan, type II collagen, and keratin 19 proteins. Cross-species analyses of rat and human BMSCs revealed consistent results. For potential clinical applications, BMSC loaded with photo-crosslinked hydrogels can be injected into damaged intervertebral disc to facilitate NP regeneration.

Amphiphilic NLC-Gel formulation loaded with Sebacoyl dinalbuphine ester and Nalbuphine for localized postoperative pain management.

Opioids are powerful analgesics; however, their significant systemic adverse effects and the need for frequent administration restrict their use. Nalbuphine (NA) is a κ-agonist narcotic with limited adverse effects, but needs to be frequently administrated due to its short elimination half-life. Whereas sebacoyl dinalbuphine ester (SDE) is a NA prodrug, which can effectively prolong the analgesic effect, but lacks immediate pain relief. Therefore, in this study, a rapid and sustained local delivery formulation to introduce NA and SDE directly into surgical sites was developed. An amphiphilic nanostructured lipid carrier (NLC) poloxamer 407 (P407) gel (NLC-Gel) was developed to permit concurrent delivery of hydrophobic SDE from the NLC core and hydrophilic NA from P407, offering a dual rapid and prolonged analgesic effect. Benefiting from the thermal-sensitive characteristic of P407, the formulation can be injected in liquid phase and instantly transit into gel at wound site. NLC-Gel properties, including particle size, drug release, rheology, and stability, were assessed. In vivo evaluation using a rat spinal surgery model highlighted the effect of the formulation through pain behavior test and hematology analysis. NLC-Gels demonstrated an analgesic effect comparable with that of commercial intramuscular injected SDE formulation (IM SDE), with only 15 % of the drug dosage. The inclusion of supplemental NA in the exterior gel (PA12-Gel + NA) provided rapid drug onset owing to swift NA dispersion, addressing acute pain within hours along with prolonged analgesic effects. Our findings suggest that this amphiphilic formulation significantly enhanced postoperative pain management in terms of safety and efficacy.

Drug delivery of extracellular vesicles: Preparation, delivery strategies and applications.

Extracellular vesicles (EV) are cell-originated vesicles exhibited with characteristics similar to the parent cells. Several studies have suggested the therapeutic potential of EV since they played as an intercellular communicator and modulate disease microenvironment, and thus EV has been widely studied in cancer management and tissue regeneration. However, merely application of EV revealed limited therapeutic outcome in different disease scenario and co-administration of drugs may be necessary to exert proper therapeutic effect. The method of drug loading into EV and efficient delivery of the formulation is therefore important. In this review, the advantages of using EV as drug delivery system compared to traditional synthetic nanoparticles will be emphasized, followed by the method of preparing EV and drug loading. The pharmacokinetic characteristics of EV was discussed, together with the review of reported delivery strategies and related application of EV in different disease management.

Porous hydroxyapatite carrier enables localized and sustained delivery of honokiol for glioma treatment.

The objective of this study is to develop hydroxyapatite (HAp) particles for targeted delivery of honokiol to tumor sites after glioma surgical management. Honokiol is released from the HAp-honokiol particles inside cancer cells through endocytosis and subsequent acid lysosomal dissolution. HAp is synthesized using a co-precipitation method, and egg white is added to create porous structures. The HAp is then surface-modified with stearic acid to enhance its hydrophobicity and loaded with honokiol to form HAp-honokiol particles. The synthesized particles are of appropriate size and characteristics for cancer cell uptake. Honokiol remains attached on to the HAp particles in neutral environments due to its hydrophobic nature, but undergoes rapid burst release in acidic environments such as lysosomes. The HAp-honokiol treatment shows a delayed effect on cell viability and cytotoxicity, indicating sustained drug release without compromising drug efficacy. Flow cytometry analysis demonstrates the apoptosis pathway induced by HAp-honokiol in ALTS1C1 glioma cells. In the in vivo study using a mouse glioma model, MRI results showed a 40% reduction in tumor size after HAp-honokiol treatment. These findings suggest that HAp-honokiol particles have potential as an effective drug delivery system for the treatment of glioma.

Administration of N-Acetylcysteine to Regress the Fibrogenic and Proinflammatory Effects of Oxidative Stress in Hypertrophic Ligamentum Flavum Cells.

Ligamentum flavum hypertrophy (LFH) is a major cause of lumbar spinal stenosis (LSS). In hypertrophic ligamentum flavum (LF) cells, oxidative stress activates intracellular signaling and induces the expression of inflammatory and fibrotic markers. This study explored whether healthy and hypertrophic LF cells respond differently to oxidative stress, via examining the levels of phosphorylated p38 (p-p38), inducible nitric oxide synthase (iNOS), and α-smooth muscle actin (α-SMA). Furthermore, the efficacy of N-acetylcysteine (NAC), an antioxidant, in reversing the fibrogenic and proinflammatory effects of oxidative stress in hypertrophic LF cells was investigated by assessing the expression levels of p-p38, p-p65, iNOS, TGF-ß, α-SMA, vimentin, and collagen I under H2O2 treatment with or without NAC. Under oxidative stress, p-p38 increased significantly in both hypertrophic and healthy LF cells, and iNOS was elevated in only the hypertrophic LF cells. This revealed that oxidative stress negatively affected both hypertrophic and healthy LF cells, with the hypertrophic LF cells exhibiting more active inflammation than did the healthy cells. After H2O2 treatment, p-p38, p-p65, iNOS, TGF-ß, vimentin, and collagen I increased significantly, and NAC administration reversed the effects of oxidative stress. These results can form the basis of a novel therapeutic treatment for LFH using antioxidants.

Topical application of sebacoyl dinalbuphine ester-loaded nanostructured lipid carriers alleviate pruritus in scratching mouse model.

Sebacoyl dinalbuphine ester (SDE) is a nalbuphine (NA) prodrug capable of biotransformation in vivo and prolong the duration of NA, maximize its effect in pain and pruritus management. However, the large molecular weight, low skin penetration, and stability concerns of SDE make it difficult to be used in local skin delivery. Nanostructured lipid carrier (NLC) is a lipid-based nanoparticulate system that has the potential for formulating SDE in order to promote drug delivery through the skin. The aim of this study was to develop SDE-loaded NLC formulations (SDE-NLC) with good stability, sustained release characteristics, and sufficient antipruritic effect. SDE was successfully encapsulated into NLC and the formulation increased the stability of SDE, enhanced skin penetration through hair follicles, and sustained SDE release during pruritus management. We also demonstrated that topical application of SDE-NLCs significantly reduced the number of scratches in pruritus-induced mice. Both NA and SDE were found in the skin strata, but only NA was detectable in the plasma, indicating rapid conversion of SDE into NA. All results demonstrated that SDE-NLC formulation protected SDE from degradation in vitro, while the released prodrug was converted into NA in vivo and extended antipruritic effect. The formulation has the potential of improving the life quality of patients with chronic pruritus.

Nanostructured Lipid Carrier Gel Formulation of Recombinant Human Thrombomodulin Improve Diabetic Wound Healing by Topical Administration.

Recombinant human thrombomodulin (rhTM), an angiogenesis factor, has been demonstrated to stimulate cell proliferation, keratinocyte migration and wound healing. The objective of this study was to develop nanostructured lipid carrier (NLC) formulations encapsulating rhTM for promoting chronic wound healing. RhTM-loaded NLCs were prepared and characterized. Encapsulation efficiency was more than 92%. The rate of rhTM release from different NLC formulations was influenced by their lipid compositions and was sustained for more than 72 h. Studies on diabetic mouse wound model suggested that rhTM-NLC 1.2 µg accelerated wound healing and was similar to recombinant human epidermal growth factor-NLC (rhEGF-NLC) 20 µg. By incorporating 0.085% carbopol (a highly crosslinked polyacrylic acid polymer) into rhTM NLC, the NLC-gel presented similar particle characteristics, and demonstrated physical stability, sustained release property and stability within 12 weeks. Both rhTM NLC and rhTM NLC-gel improved wound healing of diabetic mice and cell migration of human epidermal keratinocyte cell line (HaCaT) significantly. In comparison with rhTM solution, plasma concentrations of rhTM post applications of NLC and NLC-gel formulations were lower and more sustained in 24 h. The developed rhTM NLC and rhTM NLC-gel formulations are easy to prepare, stable and convenient to apply to the wound with reduced systemic exposure, which may warrant potential delivery systems for the care of chronic wound patients.

Oxidative stress mediates age-related hypertrophy of ligamentum flavum by inducing inflammation, fibrosis, and apoptosis through activating Akt and MAPK pathways.

The role of oxidative stress in ligamentum flavum (LF) hypertrophy has not been elucidated. We hypothesize that oxidative stress induces inflammatory responses and the subsequent fibrotic processes in LF, via activation of the Akt and MAPK pathways. Specimens of LFs were collected during surgeries for lumbar disc herniation (LDH) or lumbar spinal stenosis (LSS). Part of the LF specimens underwent analyses for ROS, fibrotic markers, and inflammatory mediators, with the remainder minced for cell cultures. The cell cultures were treated with H2O2, after which the cells were lysed and analyzed via western blotting. The specimens of the LSS patients showed increased infiltration of inflammatory cells and were stained positively for MMP-3, MMP-9, vimentin, and fibronectin. The LF of the LSS patients had increased oxidative stress and inflammation compared to that of the LDH patients. In vitro analyses demonstrated that oxidative stress rapidly activated the Akt and MAPK pathways. Inflammatory mediators, iNOS and NF-κB, and fibrotic markers, including TGF-ß, ß-catenin, α-SMA and vimentin, were significantly upregulated after induction of oxidative stress. Oxidative stress activated the intrinsic apoptotic pathway. These findings revealed that oxidative stress is one of the etiological factors of LF hypertrophy, which might provide new insights into treatment approaches.

Effects of Highly Oxygenated Water in a Hyperuricemia Rat Model.

Recent years have seen a rapidly rising number of oxygenated water brands that claim to impart health benefits and increase athletic performance by improving oxygen availability in the body. Drinks with higher dissolved oxygen concentrations have in recent times gained popularity as potential ergogenic aids, despite the lack of evidence regarding their efficacy. The aim of this study was to characterize oxygenated water and assess the improvement in uric acid metabolism while identifying performance enhancements in animals administered oxygenated water. Oxygenated water was characterized by hydrogen and oxygen nuclear magnetic resonance (NMR) spectroscopy. Hyperuricemia in rats was induced by treatment with oxonic acid potassium salt, and the animals were given oxygenated drinking water before, during, or after oxonic acid treatment. Serum uric acid was measured to confirm the effects on uric acid metabolism. Following oxygenation, the full width at half maximum (FWHM) was reduced to 11.56 Hz and 64.16 Hz in the hydrogen and oxygen NMR spectra, respectively. Oxygenated water molecule clusters were reduced in size due to the reduction in FWHM. Oxygen concentration did not vary significantly with increased temperature. However, standing time played a critical role in the amount of oxygen dissolved in the water. The rat studies indicated that oxygenated water reduced serum uric acid levels and their rate of increase and enhanced uric acid metabolism. A significant improvement in uric acid metabolism and rate of increase in serum uric acid concentration was observed in hyperuricemic rats administered oxygenated water compared to that in rats administered regular water. High oxygen concentrations enhanced the rate of oxygen absorption, leading to increased glycolysis and mitochondrial protein synthesis. Therefore, oxygenated water is a potential adjuvant therapy or health food for treatment of hyperuricemia.

Calcium phosphate particles stimulate exosome secretion from phagocytes for the enhancement of drug delivery.

Exosomes are attractive potential carriers for drug delivery because of their natural function of transferring biomolecules among cells without eliciting immune responses. However, an obstacle to the application of exosomes for drug delivery is the difficulty in collecting sufficient numbers of these vesicles. In this study, we demonstrate treatment with calcium phosphate (CaP) particles could increase over two-fold the number of exosomes secreted from macrophage-like RAW264.7 cells and monocyte-like THP-1 cells. CaP particles were easily internalized into cells and dissolved in acidic late-endosomes or lysosomes, resulting in the rupture of their membranes followed by the release of Ca2+ into cytosol. Moreover, we found that exosomes secreted from cells treated with CaP particles are not contaminated by the Ca2+ released from CaP; the Ca2+ contents in exosomes secreted from CaP particle-treated cells were similar to that in exosomes from untreated control cells. This study highlights the potential for the efficient production of exosomes using CaP particles for drug delivery.

Post-exposure treatment with the oxime RS194B rapidly reactivates and reverses advanced symptoms of lethal inhaled paraoxon in macaques.

Fatalities from organophosphate (OP) insecticide result from both occupational and deliberate exposure; significantly impacting human health. Like nerve agents, insecticides are neurotoxins which target and inhibit acetylcholinesterases (AChE) in central and peripheral synapses in the cholinergic nervous system. Post-exposure therapeutic countermeasures generally include administration of atropine with a pyridinium aldoxime e.g. pralidoxime, to reactivate the OP-inhibited AChE. However, commonly used oximes inefficiently cross the bloodbrain barrier and are rapidly cleared and their benefit is debated. Recent findings have demonstrated the ability of a novel zwitterionic, centrally acting, brain penetrating oxime (RS194B) to reverse severe symptoms and rapidly reactivate sarin-inhibited AChE in macaques, but it has not been tested following OP pesticide poisoning. In the present study, the symptoms following a lethal dose of inhaled paraoxon (100ug/kg), were shown to mimic those in insecticide poisoned individuals and were also rapidly reversed in macaques by post-exposure IM administration of 80mg/kg of RS194B. This occurred with a concomitant reactivation of AChE to 40-100% in<1hr and BChE (40% in 8h). These findings will be used to develop a macaque model with RS194B as a post-exposure treatment for insecticide poisoning and generate efficacy data for approval under the FDA Animal rule.

Mesoporous hydroxyapatite as a carrier of olanzapine for long-acting antidepression treatment in rats with induced depression.

An antidepressant carrier, mesoporous hydroxyapatite olanzapine (mesoHAP-OLZ), was designed to maintain 3weeks of constant medication release. The carrier was intramuscularly (IM) injected, where cellular activity played a role in achieving the goal of constant release. The efficiency of the treatment was evaluated from 3 perspectives in in vivo studies: locomotor activities, biomarkers, and learning and memory ability. MesoHAP-OLZ can increase the locomotor activity in rats with induced depression determined by open field test (OFT) and forced swim test (FST). Serotonin (5-HT), one of the most important biomarker in depression can also be increased by mesoHAP-OLZ, leading to increased hippocampus activity as measured by functional magnetic resonance imaging (fMRI). MesoHAP-OLZ can also improve learning and memory ability in rats with induced depression during Morris water maze (MWM) test. Our findings further show that mesoHAP-OLZ can provide long-term drug release with a single IM injection, helping to solve the problem of non-adherent medication intake that often occurs in antidepressant therapy.

Development of gelatin nanoparticles conjugated with phytohemagglutinin erythroagglutinating loaded with gemcitabine for inducing apoptosis in non-small cell lung cancer cells.

Gelatin is an efficient drug delivery vehicle for attaching targeting molecules like phytohemagglutinin erythroagglutinating (PHA-E) and carrying the chemotherapeutic agent gemcitabine (GEM). Fluorescent gelatin nanoparticles (GNPs) conjugated with PHA-E and carrying gemcitabine (GNP-(PHA-E)-GEM) were synthesized by nanoprecipitation for guiding gemcitabine-loaded gelatin nanoparticles to NSCLC by PHA-E targeting. GNPs have a uniform narrow size distribution and spherical shape, and their particle size is about 290 nm. The release rate of gemcitabine from nanoparticles reached the plateau of the curve at approximately 30% within 72 hours. PHA-E conjugated nanoparticles could enhance the cellular accumulation of nanoparticles. The results showed that GNP-(PHA-E)-GEM treatment caused an increase of cell growth inhibition and cytotoxicity on NSCLC cells A-549 and H292. In an Annexin V/PI assay, treatment with GNP-(PHA-E)-GEM could induce apoptosis of cancer cells. Treatment of NSCLC cells with GNP-(PHA-E)-GEM firstly resulted in time-dependent inhibition of epidermal growth factor receptor (EGFR) and Akt phosphorylation. And it also could increase p53 phosphorylation. And then it could decrease Bad phosphorylation and increase Bax. Finally, it could result in enhancing the release of cytochrome c, which thus increases caspase-9 and caspase-3. In conclusion, GNP-(PHA-E)-GEM could induce growth inhibition and cytotoxicity, which was mediated through inhibition of EGFR phosphorylation and the switching on of p53 that causes cell apoptosis of NSCLC cells A-549 and H292. It's significant to conjugate PHA-E for targeting cancer and inhibiting EGFR phosphorylation as it could decrease the dosage of gemcitabine, which reduces side effects on normal tissue. GNP-(PHA-E)-GEM has great potential for NSCLC treatment.

Mesoporous Hydroxyapatite as Olanzapine Carrier Provides a Long-Acting Effect in Antidepression Treatment.

An antidepressant carrier was designed to maintain over 2 weeks of constant medication release. The carrier was injected into muscle, where cellular activity was employed to achieve the goal of constant release. Mesoporous hydroxyapatite (mesoHAP) was synthesized into an adequate size by a coprecipitation method; it then went through a series of hydrophobic surface modifications for olanzapine (OLZ) loading by physical absorption to produce mesoHAP-OLZ. Because of its hydrophobic nature, OLZ was not effectively released from mesoHAP-OLZ in an aqueous environment. However, once engulfed by macrophages, the lysosome/endosome hybrid ruptured due to alterations in osmotic pressure, resulting in the release of OLZ into the cytoplasm. OLZ was then exocytosed to the extracellular space due to a high calcium ion (Ca(2+)) concentration and finally reached the blood circulation. Our findings provide a useful treatment strategy to achieve long-term drug release with a single intramuscular (IM) injection, helping to solve the problem of nonadherent medication intake that often occurs in antidepressant therapy.