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Suresh K.,Central University of Costa Rica | Khandavilli U.B.R.,Central Incubator | Gunnam A.,Central University of Costa Rica | Nangia A.,Central University of Costa Rica | Nangia A.,CSIR - National Chemical Laboratory
CrystEngComm | Year: 2017

Novel salts of glibenclamide (GBA), namely glibenclamide-sodium (GBA-Na), glibenclamide-potassium (GBA-K) and glibenclamide-ammonium (GBA-NH4) were crystallized under different conditions to obtain their polymorphs, and their aqueous solubility and hydration stability studies are reported. The GBA-Na salt is dimorphic (forms I and II) and also exists as hydrate GBA-Na-H2O (form III). The GBA-K salt exists in anhydrous and hydrate forms (GBA-K, forms I and II). Crystal structure analysis of GBA-Na forms I and II showed differences in geometry of the central metal atom and ligand orientation. This kind of polymorphism of sulfonyl urea salts appears to be novel in the Cambridge Structural Database (CSD). The isostructurality of GBA-Na form I with GBA-NH4 and GBA-K form I salts is discussed. The potassium salts of GBA exhibited higher solubility compared to pure GBA. Specifically GBA-K salt forms I and II showed higher solubility by 77 fold in the water and 33 fold in phosphate buffer (pH 7) compared to the other salts. Dynamic vapor sorption (DVS) showed reversible water sorption without hysteresis for all salts, except for GBA-K form II which transformed to form I after a sorption and desorption cycle as confirmed by PXRD. © The Royal Society of Chemistry.


Sanphui P.,Central University of Costa Rica | Goud N.R.,Central University of Costa Rica | Khandavilli U.B.R.,Central Incubator | Bhanoth S.,Central Incubator | And 2 more authors.
Chemical Communications | Year: 2011

Two new crystalline polymorphs and an amorphous phase of the active curcuminoid ingredient in turmeric are reported. Curcumin polymorph 2 has higher dissolution rate and better solubility than the known polymorph 1. © 2011 The Royal Society of Chemistry.


Mannava M.K.C.,Central Incubator | Suresh K.,Central University of Costa Rica | Nangia A.,Central Incubator | Nangia A.,Central University of Costa Rica
Crystal Growth and Design | Year: 2016

Ethionamide (ETH) is an anti-tuberculosis (TB) Biopharmaceutics Classification System class II drug of poor aqueous solubility. The objective of the present study was to evaluate the solubility and bioavailability parameters of ETH cocrystals/salts with Generally Regarded as Safe (GRAS) coformers. Five cocrystals, namely, ETH-GLA (glutaric acid), ETH-ADP (adipic acid), ETH-SBA (suberic acid), ETH-SEBA (sebacic acid), ETH-FA (fumaric acid), and one salt ETH-OA (oxalic acid) were prepared by liquid-assisted grinding, and their structural characterization was carried out using spectroscopic, thermal, and powder X-ray diffraction techniques. The crystal structures of ETH-ADP, ETH-SBA, ETH-FA, and ETH-OA were confirmed by X-ray diffraction. The three cocrystal structures are sustained by the robust acid⋯pyridine synthon, while the ETH-OA salt has an ionic N-H⋯O hydrogen bond between carboxylate and pyridinium ions. The ETH-OA salt exhibited the highest dissolution compared to ETH (25 times), and its cocrystals (10 to 2 times higher). The intrinsic dissolution rates are ETH-OA > ETH-GLA > ETH-FA > ETH-SBA > ETH-ADP > ETH-SEBA > ETH. The best crystal form of ETH-OA was administered orally and exhibited 2.5 times enhanced plasma concentration in rats with Cmax of 4.08 ± 0.2 μg mL-1at Tmax of 30 min, and AUC(0-8h) increased 1.9 fold to 6.49 ± 0.19 μg mL-1 h-1 compared to ETH. The oxalate salt exhibits the highest bioavailability enhancement for BCS class II drug ethionamide. © 2016 American Chemical Society.


Suresh K.,Central University of Costa Rica | Mannava M.K.C.,Central Incubator | Nangia A.,Central University of Costa Rica | Nangia A.,Central Incubator
Chemical Communications | Year: 2016

Two isomorphous cocrystals of nitazoxanide (NTZ) with p-aminosalicylic acid (PASA) and p-aminobenzoic acid (PABA) as well as their alloys were prepared by slurry and grinding techniques. The cocrystals exhibit faster dissolution rates and higher pharmacokinetic properties compared to the reference drug, and surprisingly the cocrystal alloy NTZ-PABA: NTZ-PASA (0.75: 0.25) exhibited 4 fold higher bioavailability of NTZ in Sprague Dawley rats. This study opens the opportunity for cocrystal alloys as improved medicines. © The Royal Society of Chemistry 2016.


Babu N.J.,Central University of Costa Rica | Sanphui P.,Central University of Costa Rica | Nath N.K.,Central University of Costa Rica | Khandavilli U.B.R.,Central Incubator | And 2 more authors.
CrystEngComm | Year: 2013

The X-ray crystal structure of temozolomide hydrochloride shows that the dihydrate salt contains one neutral temozolomide, one temozolomide-H +Cl-, one H3O+·Cl -, and three water molecules. This is the first crystallographic evidence of a protonated form of the antitumour drug temozolomide. The protonation of water O and imidazole N of the drug are rationalized by calculated pKas. © 2013 The Royal Society of Chemistry.


Rao Khandavilli U.B.,Central Incubator | Gangavaram S.,Central Incubator | Rajesh Goud N.,Central University of Costa Rica | Cherukuvada S.,Central University of Costa Rica | And 6 more authors.
CrystEngComm | Year: 2014

Novel sodium and potassium salts of the poorly soluble loop diuretic drug furosemide were prepared with the intent of improving drug solubility and bioavailability. Furo-Na salt was obtained as a trihydrate upon crystallization from aqueous NaOH solution, and furo-K salt crystallized as a monohydrate from KOH solution. Both salt hydrates were characterized by X-ray diffraction, DSC, TGA, and IR spectroscopy. An exothermic phase transition at 165 °C in the DSC heating curve of the furo-Na salt indicates the likelihood of polymorphism in its anhydrate phase. Based on solubility studies, furo-Na-trihydrate and furo-K-monohydrate in pH 7 phosphate buffer medium exhibited significantly higher aqueous solubilities of 41 mg mL-1 and 106 mg mL-1 compared to the free drug (0.01 mg mL-1). The physical stability of these fast dissolving salts under accelerated ICH conditions of 40 °C and 75% RH was modest, with furo-Na salt being stable for 2 weeks and furo-K salt for 1 week. © 2014 the Partner Organisations 2014.


Suresh K.,Central University of Costa Rica | Chaitanya Mannava M.K.C.,Central Incubator | Nangia A.,Central University of Costa Rica | Nangia A.,Central Incubator
RSC Advances | Year: 2015

Here we report a curcumin-artemisinin coamorphous solid (1:1) prepared by rotavaporization and a dramatic increase in the pharmacokinetic profile of curcumin (AUC0-12 2.6 μg h mL-1, Cmax 1 μg mL-1) administered as CUR-ART to SD rats. PXRD and FESEM analysis explains the molecular basis for the solubility enhancement of coamorphous CUR-ART. © 2014 The Royal Society of Chemistry.


Gangavaram S.,Central Incubator | Raghavender S.,Central Incubator | Sanphui P.,Central University of Costa Rica | Pal S.,Astrazeneca | And 4 more authors.
Crystal Growth and Design | Year: 2012

Only one X-ray crystal structure of the parent quinolone antibiotic nalidixic acid is known in the published and patent literature. A systematic search for new solid-state forms of the drug yielded two polymorphs (forms II and III) and six cocrystals with resorcinol, catechol, hydroquinone, pyrogallol, orcinol, and phloroglucinol. Of these, X-ray crystal structures were determined for polymorph II and cocrystals with resorcinol, catechol, hydroquinone, and pyrogallol, whereas the remaining solid forms were identified by their unique powder X-ray diffraction patterns. Nalidixic acid is intramolecularly O-H⋯O hydrogen bonded in a six-member ring, and its molecular dimers are assembled via C-H⋯O synthon. The OH donors on phenolic coformers H bond with the α-keto acid moiety of the drug as connectors and spacers. Intermolecular drug-drug C-H⋯O interactions in polymorphs are replaced by strong drug-coformer O-H⋯O hydrogen bonds in cocrystals. © 2012 American Chemical Society.


PubMed | Central Incubator and Central University of Costa Rica
Type: Journal Article | Journal: Chemical communications (Cambridge, England) | Year: 2016

Two isomorphous cocrystals of nitazoxanide (NTZ) with p-aminosalicylic acid (PASA) and p-aminobenzoic acid (PABA) as well as their alloys were prepared by slurry and grinding techniques. The cocrystals exhibit faster dissolution rates and higher pharmacokinetic properties compared to the reference drug, and surprisingly the cocrystal alloy NTZ-PABA:NTZ-PASA (0.75:0.25) exhibited 4 fold higher bioavailability of NTZ in Sprague Dawley rats. This study opens the opportunity for cocrystal alloys as improved medicines.

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