Nanoconfinement of a Pharmaceutical Cocrystal with Praziquantel in Mesoporous Silica: The Influence of the Solid Form on Dissolution Enhancement.

Nanoconfinement is a recent strategy to enhance solubility and dissolution of active pharmaceutical ingredients (APIs) with poor biopharmaceutical properties. In this work, we combine the advantage of cocrystals of racemic praziquantel (PZQ) containing a water-soluble coformer (i.e., increased solubility and supersaturation) and its confinement in a mesoporous silica material (i.e., increased dissolution rate). Among various potential cocrystalline phases of PZQ with dicarboxylic acid coformers, the cocrystal with glutaric acid (PZQ-GLU) was selected and successfully loaded by the melting method into nanopores of SBA-15 (experimental pore size of 5.6 nm) as suggested by physical and spectroscopic characterization using various complementary techniques like N2 adsorption, powder X-ray diffraction (PXRD), infrared spectroscopy (IR), solid-state NMR (ss-NMR), differential scanning calorimetry (DSC), and field emission-scanning electron microscopy (FE-SEM) analysis. The PZQ-GLU phase confined in SBA-15 presents more mobility according to ss-NMR studies but still retains its cocrystal-like features in the IR spectra, and it also shows depression of the melting transition temperature in DSC. On the contrary, pristine PZQ loaded into SBA-15 was found only in the amorphous state, according to the aforementioned studies. This dissimilar behavior of the composites was attributed to the larger crystal lattice of PZQ over the PZQ-GLU cocrystal (3320.1 vs 1167.9 Å3) and to stronger intermolecular interactions between PZQ and GLU, facilitating the confinement of a more mobile solid-like phase in the constrained channels. Powder dissolution studies under extremely nonsink conditions (SI = 0.014) of the confined PZQ-GLU and amorphous PZQ phases embedded in mesoporous silica showed transient supersaturation behavior when dissolving in simulated gastric fluid (HCl pH 1.2 at 37 ± 0.5 °C) in a similar fashion to the bare cocrystal PZQ-GLU. A comparison of the area under the curve (AUC0-90 min) of the dissolution profiles afforded a dissolution advantage of 2-fold (p < 0.05) of the new solid phases over pristine racemic PZQ after 90 min; under these conditions, the solubilized API reprecipitated as the recently discovered PZQ hemihydrate (PZQ-HH). In the presence of a cellulosic polymer, sustained solubilization of PZQ from composites SBA-15/PZQ or SBA-15/PZQ-GLU was observed, increasing AUC0-90 min up to 5.1-fold in comparison to pristine PZQ. The combination of a confined solid phase in mesoporous silica and a methylcellulose polymer in the dissolution medium effectively maintained the drug solubilized during times significant to promote absorption. Finally, powder dissolution studies under intermediate nonsink conditions (SI = 1.99) showed a fast release profile from the nanoconfined PZQ-GLU phase in SBA-15, which reached rapid saturation (95% drug dissolved at 30 min); the amorphous PZQ composite and bare PZQ-GLU also displayed an immediate release of the API but at a lower rate (69% drug dissolved at 30 min). In all of these cases, a large dissolution advantage was observed from any of the novel solid phases over PZQ.

Identification of novel modulators of a schistosome transient receptor potential channel targeted by praziquantel.

Given the worldwide burden of neglected tropical diseases, there is ongoing need to develop novel anthelmintic agents to strengthen the pipeline of drugs to combat these burdensome infections. Many diseases caused by parasitic flatworms are treated using the anthelmintic drug praziquantel (PZQ), employed for decades as the key clinical agent to treat schistosomiasis. PZQ activates a flatworm transient receptor potential (TRP) channel within the melastatin family (TRPMPZQ) to mediate sustained Ca2+ influx and worm paralysis. As a druggable target present in many parasitic flatworms, TRPMPZQ is a promising target for a target-based screening campaign with the goal of discovering novel regulators of this channel complex. Here, we have optimized methods to miniaturize a Ca2+-based reporter assay for Schistosoma mansoni TRPMPZQ (Sm.TRPMPZQ) activity enabling a high throughput screening (HTS) approach. This methodology will enable further HTS efforts against Sm.TRPMPZQ as well as other flatworm ion channels. A pilot screen of ~16,000 compounds yielded a novel activator of Sm.TRPMPZQ, and numerous potential blockers. The new activator of Sm.TRPMPZQ represented a distinct chemotype to PZQ, but is a known chemical entity previously identified by phenotypic screening. The fact that a compound prioritized from a phenotypic screening campaign is revealed to act, like PZQ, as an Sm.TRPMPZQ agonist underscores the validity of TRPMPZQ as a druggable target for antischistosomal ligands.

In-silico screening for DNA-dependent protein kinase (DNA-PK) inhibitors: Combined homology modeling, docking, molecular dynamic study followed by biological investigation.

DNA-dependent protein kinase (DNA-PK) is a key enzyme in non-homologous DNA end joining (NHEJ) repair pathway. The targeted inhibition of such enzyme would furnish a valuable option for cancer treatment. In this study we report the development of validation of enzyme homology model, and the subsequent use of this model to perform docking-based virtual screening against a database of FDA-approved drugs. The nominated highest ranking hits (Praziquantel and Dutasteride) were subjected to biological investigation. Additionally, molecular dynamic study was carried-out for binding mode exploration. Results of the biological evaluation revealed that both compounds inhibit the DNA-PK enzymatic activity at relatively high concentration levels with an IC50 of 17.3µM for praziquantel and >20µM for dutasteride. Furthermore, both agents enhanced the anti-proliferative effects of doxorubicin and cisplatin on breast cancer (MCF7) and lung cancer (A549) cell lines. This result indicates that these two hits are good candidate as DNA-PK inhibitors and worth further structural modifications to enhance their enzyme inhibitory effects.

Nanoencapsulated curcumin and praziquantel treatment reduces periductal fibrosis and attenuates bile canalicular abnormalities in Opisthorchis viverrini-infected hamsters.

This study investigated the effects of nanoencapsulated curcumin (NEC) and praziquantel (PZQ) treatment on the resolution of periductal fibrosis (PDF) and bile canalicular (BC) abnormalities in Opisthorchis viverrini infected hamsters. Chronic O. viverrini infection (OV) was initially treated with either PZQ (OP) and subsequently treated with NEC (OP+NEC), curcumin (OP+Cur) or unloaded carriers (OP+carrier) daily for one month. OP+NEC treatment reduced the PDF by suppression of fibrotic markers (hydroxyproline content, α-SMA, CTGF, fibronectin, collagen I and III), cytokines (TGF-ß and TNF-α) and TIMP-1, 2, 3 expression and upregulation of MMP-7, 13 genes. Higher activity of NEC in reducing fibrosis compared to curcumin was also demonstrated in in vitro studies. Moreover, OP+NEC also prevented BC abnormalities and upregulated several genes involved in bile acid metabolism. These results demonstrate that NEC and PZQ treatment reduces PDF and attenuates BC defect in experimental opisthorchiasis. From the Clinical Editor: Infection by Opisthorchis viverrini leads to liver fibrosis and affects population in SE Asia. Currently, praziquantel (PZQ) is the drug of choice but this drug has significant side effects. In this study, the authors combined curcumin (NEC) and praziquantel in a nanocarrier to test the anti-oxidative effect of curcumin in an animal model. The encouraging results may pave a way for better treatment in the future.

[Effects of Omphalia lapidescens and Praziquantel on the Infectivity and Ultrastructure of Spirometra erinacei Plerocercoids].

OBJECTIVE: To study the effects of Omphalia lapidescens and praziquantel on the infectivity and ultrastructure of Spironetra erinacei plerocercoids. METHODS: The plerocercoids were taken from frogs (Rana nigromaculata). A total of 168 mice were divided into 21 groups (8 mice per group), each of them was orally infected with 5 plerocercoids. The mice in group 1-9 were inoculated with plerocercoids cultured in media respectively containing different concentrations of O. lapidescens suspension (20, 40 or 80 mg/ml) for 4, 12 or 24 h, respectively. The mice in group 10-18 were inoculated with plerocercoids cultured in media respectively containing different concentrations of praziquantel (20, 80 or 320 µg/ml) for 4, 12 or 24 h, respectively. The mice in group 19-21 were inoculated with plerocercoids cultured in normal culture fluid for 4, 12 or 24 h, respectively, and served as controls. One week after infection, the mice were sacrificed to collect the plerocercoids. Worm reduction rate was calculated. The ultrastructure changes of plerocercoids were observed under transmission electron microscope (TEM) and scanning electron microscope (SEM), respectively. RESULTS: The average number of plerocercoids detected from mice infected by pleroceroids treated with 40, 80 mg/ml O. lapidescens suspension for 4, 12 or 24 h were 1.6, 1.0, and 0.3; 0.3, 0, and 0, respectively, and significantly lower than that of the infected controls (4.1, 3.5 and 3.3) (P < 0.05); the worm reduction rates were 60.0%, 71.4%, and 90.1%; 92.7%, 100%, and 100%, respectively. The average number of pleroceroids detected from mice infected with pleroceroids treated with 320 µg/ml praziquantel for 4, 12, or 24 h were 1.9, 1.3, and 0.4, and significantly lower than that of the infected controls (P < 0.05); the worm reduction rates were 53.7%, 62.9%, and 87.9%, and lower than that of 20 µg/ml praziquantel group (14.6%, 2.9%, and 6.1%) and 80 µg/ml praziquantel group (24.4%, 17.1%, and 24.2%) (P < 0.05). The ultrastructure of plerocercoids cultured in 20 mg/ml O. lapidescens suspension, 20 or 80 µg/ml praziquantel for 4, 12 or 24 h had no significant difference compared with control groups. The plerocercoids cultured in 40 mg/ml O. lapidescens for 4 h or 320 µg/ml praziquantel for 4 or 12 h, showed mild contracture. The pleroceroids cultured in 40 mg/ml O. lapidescens for 12-24 h showed: agglutinate, fusion, fracture or abscission of microtriches, breakdown of plasma membrane, excretion of calcareous corpuscles, and tegument tissue damages. After cultured in 80 mg/ml of O. lapidescens for 24 h, the tissues of plerocercoid were damaged seriously. After cultured in 320 µg/ml praziquantel for 24 h, the plerocercoids showed: obvious contracture in the anterior end of plerocercoid, edema and bulge of plasma membrane, morphological changes of calcareous corpuscles, increase of secretory granules, glycogen depletion, and chromatin compaction in flame cells. CONCLUSION: The infectivity of Spironetra erinacei plerocercoids decreases along with the time of culture and the increase of drug concentration. Omphalia lapidescens and praziquantel can cause extensive tissue damage to the plerocercoids in vitro, and the effect of 0. lapidescens on the infectivity and ultrastructure of plerocercoid is more considerable than that of praziquantel.

Solid lipid nanoparticle suspension enhanced the therapeutic efficacy of praziquantel against tapeworm.

Hydatid disease caused by tapeworm is an increasing public health and socioeconomic concern. In order to enhance the therapeutic efficacy of praziquantel (PZQ) against tapeworm, PZQ-loaded hydrogenated castor oil solid lipid nanoparticle (PZQ-HCO-SLN) suspension was prepared by a hot homogenization and ultrasonication method. The stability of the suspension at 4°C and room temperature was evaluated by the physicochemical characteristics of the nanoparticles and in-vitro release pattern of the suspension. Pharmacokinetics was studied after subcutaneous administration of the suspension in dogs. The therapeutic effect of the novel formulation was evaluated in dogs naturally infected with Echinococcus granulosus. The results showed that the drug recovery of the suspension was 97.59% ± 7.56%. Nanoparticle diameter, polydispersivity index, and zeta potential were 263.00 ± 11.15 nm, 0.34 ± 0.06, and -11.57 ± 1.12 mV, respectively and showed no significant changes after 4 months of storage at both 4°C and room temperature. The stored suspensions displayed similar in-vitro release patterns as that of the newly prepared one. SLNs increased the bioavailability of PZQ 5.67-fold and extended the mean residence time of the drug from 56.71 to 280.38 hours. Single subcutaneous administration of PZQ-HCO-SLN suspension obtained enhanced therapeutic efficacy against tapeworm in infected dogs. At the dose of 5 mg/kg, the stool-ova reduction and negative conversion rates and tapeworm removal rate of the suspension were 100%, while the native PZQ were 91.55%, 87.5%, and 66.7%. When the dose reduced to 0.5 mg/kg, the native drug showed no effect, but the suspension still got the same therapeutic efficacy as that of the 5 mg/kg native PZQ. These results demonstrate that the PZQ-HCO-SLN suspension is a promising formulation to enhance the therapeutic efficacy of PZQ.