Preparation and physicochemical properties of niclosamide anhydrate and two monohydrates

Tonder, E. C. Van; Maleka, Tshoane S.P.; Liebenberg, Wilna; Song, Mingna; Wurster, Dale Eric; Villiers, Melgardt M. de

doi:10.1016/j.ijpharm.2003.09.035

Cited by 69 publications

(95 citation statements)

References 8 publications

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“…1) is used as an anthelmintic, mainly for the treatment of worm infestations in humans and animals, namely, ruminants, ostriches, poultry, cats, and dogs. 24 A significant antituberculosis activity for NC was also found in previous studies, with a minimal inhibitory concentration of 0.5 to 1 µg ml 1 . 25 Many studies indicate that NC crystallizes into a number of solvated forms, two monohydrates (usually labeled as H A and H B ) and one anhydrous form.…”

Section: Introductionsupporting

confidence: 64%

“…25 Many studies indicate that NC crystallizes into a number of solvated forms, two monohydrates (usually labeled as H A and H B ) and one anhydrous form. 24,26 It is well documented that NC is sensitive to polymorphic and pseudopolymorphic transformations that affect its dissolution profiles and, consequently, its bioavailability. 24,26 -28 Changes in relative humidity (RH) conditions promote reversible conversion between the anhydrous form (hereafter named as NCa) and the H A monohydrate (hereafter named as NCh).…”

Section: Introductionmentioning

confidence: 99%

“…24,26 -28 Changes in relative humidity (RH) conditions promote reversible conversion between the anhydrous form (hereafter named as NCa) and the H A monohydrate (hereafter named as NCh). 24,26 Other possible polymorphs/pseudopolymorphs described in the literature (such as H B monohydrate) are not part of this conversion path. The hydrated form is expected to present hydrogen-bonding networks involving water molecules, which are absent in the NCa form.…”

Section: Introductionmentioning

confidence: 99%

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Pseudopolymorphic transitions of niclosamide monitored by Raman spectroscopy

Sardo¹,

Amado²,

Ribeiro‐Claro³

2008

J Raman Spectroscopy

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Niclosamide suffers pseudopolymorphic transformations when exposed to different ambient conditions, which can lead to changes in its bioavailability. In this study, the kinetics of the pseudopolymorphic transitions of niclosamide crystals are characterized. FT-Raman spectroscopy is used to quantify the anhydrate and hydrate forms of niclosamide crystals, mostly because of its high sensitivity to the strong intermolecular interactions present in these systems. The samples are exposed to well-characterized relative humidity (RH) conditions during different periods of time and both water diffusion and polymorphic changes are monitored from the corresponding changes observed in the vibrational spectra. Both hydration and dehydration were found to be single-step processes, with a half-life time of ca. 142 and 63 h, respectively, at 24°C.

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Section: Introductionsupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pseudopolymorphic transitions of niclosamide monitored by Raman spectroscopy

Sardo¹,

Amado²,

Ribeiro‐Claro³

2008

J Raman Spectroscopy

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“…The stability order according to the partial molar heats of solution was in the order anhydrate > > TEG hemisolvate > MeOH solvate > DMSO solvate >> DMF solvate > monohydrate H A 8 > monohydrate H B . 8 However, although these values are different it should be emphasized that the heat of solution difference between polymorphs or solvates will be maintained only when the less stable form cannot convert to the most stable form. Since, in this study, such a conversion to the more stable monohydrated form does takes place, the equilibrium heat of solution of all the forms seems to approach a common value (mean for the solvates 6.13 ± 0.41 kJ/mol); namely, that of the more stable monohydrate H A (6.51 kJ/mol).…”

Section: Thermal Properties Of the Solvatesmentioning

confidence: 99%

“…This finding meant that, with the dissolution conditions used, all the solvated forms were converted to a monohydrated form, monohydrate H A . Although H B is the most stable form, 8 the transformation to H B is a time-consuming process, and the time it took to complete an intrinsic dissolution test was insufficient for complete conversion. Previous studies also showed that monohydrate H A could act as an intermediate phase in the formation of H A .…”

Section: Dissolution Properties Of the Solvatesmentioning

confidence: 99%

Preparation and physicochemical characterization of 5 niclosamide solvates and 1 hemisolvate

Tonder¹,

Mahlatji²,

Malan³

et al. 2004

AAPS PharmSciTech

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INTRODUCTIONThe purpose of the study was to characterize the physicochemical, structural, and spectral properties of the 1:1 niclosamide and methanol, diethyl ether, dimethyl sulfoxide, N,N' dimethylformamide, and tetrahydrofuran solvates and the 2:1 niclosamide and tetraethylene glycol hemisolvate prepared by recrystallization from these organic solvents. Structural, spectral, and thermal analysis results confirmed the presence of the solvents and differences in the structural properties of these solvates. In addition, differences in the activation energy of desolvation, batch solution calorimetry, and the aqueous solubility at 25°C, 24 hours, showed the stability of the solvates to be in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > methanol solvate > dimethyl sulfoxide solvate > N,N' dimethylformamide solvate. The intrinsic and powder dissolution rates of the solvates were in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > N,N' dimethylformamide solvate > methanol solvate > dimethyl sulfoxide solvate. Although these nonaqueous solvates had higher solubility and dissolution rates than the monohydrous forms, they were unstable in aqueous media and rapidly transformed to one of the monohydrous forms.

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Insight into Crystallization Mechanisms of Polymorphic Hydrate Systems

Tian

Louhi-Kultanen

et al. 2010

Chem Eng & Technol

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Polymorphic anhydrate systems have been well studied but until now little attention has been paid to polymorphic hydrate systems. The incorporation of water molecules can complicate the whole polymorphic system and thus impede the control of the crystallization process. In this work, nitrofurantoin monohydrate polymorphs which have the same chemical composition and molar ratio of water but different crystal packing arrangements, have been investigated. The metastable nitrofurantoin monohydrate was found to be difficult to crystallize, where both evaporative and cooling crystallization failed in its production. The possible phase conversion of the nitrofurantoin hydrate polymorphic system was also investigated in a liquid-assisted ball milling process. High-energy solids, e.g., amorphous and cocrystals, have often been created during high-energy ball milling. Metastable nitrofurantoin monohydrate, however, was again not observed during the whole milling process, in contrast to another polymorphic hydrate system, namely niclosamide. During milling of niclosamide anhydrate in ethyl acetatewater mixture the metastable niclosamide monohydrate was formed immediately upon milling (2 min). Under further milling, the metastable niclosamide hydrate started converting to the stable niclosamide hydrate (from 30 min onwards). IntroductionHydrates are the most common solvates encountered in pharmaceutical compounds, since water and mixtures of water and an organic solvent are frequently used in pharmaceutical processing, e.g., in crystallization and granulation. It has been estimated that approximately one-third of active pharmaceutical ingredients (APIs) are capable of forming a hydrate [1]. Among them, some compounds can form different hydrates by incorporating different amounts of water. Hydrates can also form polymorphs in which hydrates with the same chemical composition and molar ratio of water have different crystal packing arrangements [2][3][4][5]. Different hydrates of a particular compound or polymorphs of a hydrate have different physical properties. In aqueous environment it is unlikely that the most thermodynamically stable hydrate can be overlooked but the formation of stable hydrates may mask the existence of other less stable hydrate forms. Therefore, discovery of a less stable hydrate can be coincidently and sometimes difficult. Several metastable hydrates were only recently discovered [6,7]. This applies similarly to the metastable nitrofurantoin hydrate polymorph. The two nitrofurantoin hydrate polymorphs (monohydrate I and II) have been reported by Pienaar et al. in 1993 [5]. These two hydrates have the same chemical composition and same molar ratio of water in crystalline lattice, differing only in the crystal packing arrangements. Since 1993, a number of studies have investigated nitrofurantoin hydrate [5,[8][9][10][11][12][13][14][15], but only two of them have observed the formation of metastable nitrofurantoin hydrate polymorph (monohydrate I) [14,15]. Crystallization of this metastable nitrofuranto...

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Preparation and physicochemical properties of niclosamide anhydrate and two monohydrates

Cited by 69 publications

References 8 publications

Pseudopolymorphic transitions of niclosamide monitored by Raman spectroscopy

Pseudopolymorphic transitions of niclosamide monitored by Raman spectroscopy

Preparation and physicochemical characterization of 5 niclosamide solvates and 1 hemisolvate

Insight into Crystallization Mechanisms of Polymorphic Hydrate Systems

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