Mebendazole Mesylate Monohydrate: A New Route to Improve the Solubility of Mebendazole Polymorphs

Mebendazolium mesylate anhydride salt: rational design based on supramolecular assembly, synthesis, and solid-state characterization

The design mebendazole (MBZ) multicomponent systems is important to obtain new materials that incorporate the API (active pharmaceutical ingredient) with better thermal stability, avoiding the interconversion of desmotropes. Interestingly, the presence of water molecules in the mebendazolium mesylate monohydrate prevents the formation of the R22(8) supramolecular synthon, found in all mebendazolium salts with polyatomic counterions. Here, we designed a new mebendazolium mesylate anhydrous salt based on statistical scrutiny of all mebendazole crystal structures identified in the literature and an exhaustive analysis of the conformational and geometrical requirements for the supramolecular assembly. The synthesis of this new salt and its solid-state characterization through single-crystal X-ray diffraction and complementary techniques are presented. As expected, mebendazole recrystallization in methanol with methanesulfonic acid - a Food and Drug Administration accepted coformer - in the absence of water yields a mesylate anhydrous salt with 1 : 1 stoichiometry. This new salt crystallizes in the P212121 (19) space group. The main intermolecular interactions found in the crystal structure are the hydrogen bonds that form a R22(8) supramolecular motif that assembles the ionic pairs. Additional non-classical H-bond, as well as π⋯π and carbonyl⋯cation interactions, contribute to the final stabilization of the crystal packing. This new salt is stable up to 205 °C when it undergoes the endothermic loss of the ester moiety to yield 2-amino-5-benzoylbenzimidazole. Moreover, preliminary dissolution experiments in aqueous 0.1 mol L-1 HCl suggest an apparent solubility of mebendazolium mesylate anhydride 2.67 times higher than that of the preferred for pharmaceutical formulations MBZ form C.

Anti-hydatidosis Potential of Sodium Valproate: Evaluating New Therapeutic Potential for Sodium Valproate

Background: Larval stage of Echinococcus granulosus is the main cause of the hydatid cyst. Surgery, which is both aggressive and high-risk, is the most common treatment for this type of cyst. Some medicines, such as mebendazole, are also used as a complementary approach to preventing the recurrence of hydatid cysts. Objectives: Considering the approved antiparasitic effects of sodium valproate (VPA) on some parasites, this research intended to examine the potential of VPA against protoscolices and hydatid walls. Methods: Liver hydatid cysts caused by E. granulosus were collected from a slaughterhouse. Protoscolices and hydatid cysts were exposed to RPMI and dimethyl sulfoxide (DMSO) media (control groups) or different concentrations of VPA and mebendazole in vitro. The viability of protoscolices was evaluated via light microscopy. Also, tissue changes and expression of apoptotic caspase-3 were examined in hydatid cyst walls (HCWs) using histological and immunohistochemical methods, respectively. Results: The mortality rates of VPA-treated and mebendazole-treated protoscolices were dose- and time-dependent. There was a significant difference between the intervention and control groups (P < 0.05). Tissue changes and apoptosis were observed in VPA-treated and mebendazole-treated HCWs. Conclusions: Valproate and mebendazole had significant effects on protoscolices and HCWs, although VPA exerted its effects more rapidly. It seems that VPA can be a new promising protoscolicidal agent and anti-hydatid medicine.

Rational design, supramolecular synthesis and solid state characterization of two bicomponent solid forms of mebendazole

MBZ methyl sulfate and perchlorate were designed based on the statistical probability of the formation of an R22(8) supramolecular heterosynthon.

N-Substituted Prodrugs of Mebendazole Provide Improved Aqueous Solubility and Oral Bioavailability in Mice and Dogs

Mebendazole (MBZ) was developed as a broad-spectrum anthelmintic but has recently shown efficacy as an anticancer agent. The use of MBZ for cancer, however, is challenging due to its poor solubility leading to poor bioavailability. Herein, we developed a prodrug approach with various N-linked promoieties including acyloxymethyl, aminoacyloxymethyl, and substituted phosphonooxymethyl in attempt to improve these characteristics. Compound 12, containing an (((((isopropoxycarbonyl)oxy)methoxy)phosphoryl)oxy)methyl promoiety, showed a >10 000-fold improvement in aqueous solubility. When evaluated in mice, 12 displayed a 2.2-fold higher plasma AUC_{0- t} and a 1.7-fold improvement in brain AUC_{0- t} with a calculated oral bioavailability of 52%, as compared to 24% for MBZ-polymorph C (MBZ-C), the most bioavailable polymorph. In dogs, 12 showed a 3.8-fold higher plasma AUC_{0- t} with oral bioavailability of 41% compared to 11% for MBZ-C. In summary, we have identified a prodrug of MBZ with better physicochemical properties and enhanced bioavailability in both mice and dog.

Novel pharmaceutical salts of albendazole

Novel pharmaceutical salts of albendazole drugs are crystallized with sulfonic acids and carboxylic acids. The disorder of the thiopropyl chain in the parent crystal structure is resolved in the salt crystal structures.

Solid-state supramolecular synthesis based on the N-H…O heterosynthon: an approach to solve the polymorphism problem in famotidine

Famotidine (FMT), a histamine H2 -receptor antagonist, is a drug commonly used in treatments of gastroesophageal diseases that presents solid-state polymorphism (A and B forms), the marketed form being the metastable polymorph B. A new stable salt was obtained by combination of FMT and maleic acid as coformer. FMT maleate (FMT-MLT) was prepared either by solvent evaporation or comilling methods. Single-crystal X-ray diffraction reveals that (FMT)(+) in FMT-MLT adopts an extended conformation that is stabilized by classical and nonclassical H-bonds. The three-dimensional packing consists of tapes along the axis b that further develop a columnar array based on H-bonds involving (FMT)(+) side chain. Nonconventional π-stacking interactions between adjacent tapes were also identified. Fourier transform infrared, differential scanning calorimetry, thermogravimetric analysis, polarized light thermal microscopy, and scanning electron microscopy were employed to characterize the multicomponent complex. According to the solubility values in water and simulated gastric fluid, FMT-MLT exhibits such a performance that improves on the solubility of the commercially available polymorph. Finally, the higher stability of FMT-MLT regarding both FMT forms, as well as its easy preparation from either A or B forms or a mixture of them, also allows to consider this salt as a valuable alternative to avoid the polymorphism issue in marketed formulations containing FMT.