Solubility, dissolution rate and phase transition studies of ranitidine hydrochloride tautomeric forms

Mirmehrabi, Mahmoud; Rohani, Sohrab; Murthy, K. S. Keshava; Radatus, Bruno

doi:10.1016/j.ijpharm.2004.05.031

Cited by 63 publications

(37 citation statements)

References 10 publications

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“…Figure 8a shows the absorption spectra obtained before and during the photochemical degradation of ranitidine. Spectrum 1, obtained before irradiation, reveals two major absorption bands at 224 and 312 nm, which are related to the nitroethenediamine moiety and the furanyl group, respectively [23]. Absorption at 312 nm decreases during irradiation, accompanied by a decreased absorption shifted towards wavelengths lower than 220 nm.…”

Section: Mechanistic Aspectsmentioning

confidence: 99%

Removal of drugs in aqueous systems by photoassisted degradation

et al. 2005

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Aqueous solutions of tetracycline, lincomycin and ranitidine were irradiated with UV light in homogeneous and heterogeneous systems. Two commercial polycrystalline TiO 2 powders (Degussa P25 and Merck) were used as photocatalysts. After 5 h, an appreciable photolytic degradation of tetracycline and ranitidine was observed while the degradation of lincomycin was noticeably lower. As far as the mineralization is concerned, a small decrease of the TOC values was measured in the case of tetracycline whereas negligible variations were found for lincomycin or ranitidine. The presence of the photocatalysts greatly enhanced the degradation rates of the drugs with respect to those observed during the homogeneous experiments. The Langmuir-Hinshelwood kinetic model adequately describes the experimental results and both the pseudo-first order kinetic constants of the reactions and the adsorption constants were calculated. Merck TiO 2 was more active than P25 Degussa for the photodegradation of tetracycline and ranitidine, whereas both photocatalysts showed similar performances for lincomycin. In the presence of TiO 2 Degussa P25, tetracycline was almost completely mineralized, but the reduction of the initial TOC was ca. 60% in the case of lincomycin and ranitidine. A less significant mineralization was observed by using Merck TiO 2 .

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Section: Mechanistic Aspectsmentioning

confidence: 99%

Removal of drugs in aqueous systems by photoassisted degradation

et al. 2005

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“…Tablets were pressed in a KBr press (Perkin Elmer, USA) with a 13 mm diameter die for 1 min under 1 × 10 4 N and had flat surfaces. Mirmehrabi et al [6] have previously shown that tableting does not induce conversion between the two polymorphic forms, and comparison of pure form I and II tablet and capsule spectra indicated no polymorph conversion occurred. The capsules were filled by hand.…”

Section: Sample Preparationmentioning

confidence: 97%

“…[4] The two polymorphs are equivalent in terms of bioavailability and therapeutic efficacy, [5] though the stability of the two forms under different conditions remains unclear. It has been suggested that form II is more stable than form I on the basis of its higher melting point; however, Miremehrabi et al [6] have shown that manual grinding in a mortar and pestle and tableting does not cause polymorphic conversion. Hence, both forms of ranitidine hydrochloride are used in commercial formulations, leading to the two polymorphs being the source of litigation over patent infringement claims.…”

Section: Introductionmentioning

confidence: 99%

Pharmaceutical polymorphs quantified with transmission Raman spectroscopy

McGoverin

Hargreaves

Matousek

et al. 2011

J Raman Spectroscopy

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The quantification of polymorphs in dosage forms is important in the pharmaceutical industry. Conventional Raman spectroscopy of solid-state pharmaceuticals may be used for this, but it has some limitations such as sub-sampling and fluorescence. These problems can be mitigated through the use of transmission Raman spectroscopy (TRS). The efficacy of TRS measurements for the prediction of polymorph content was evaluated using a ranitidine hydrochloride test system. Four groups of ranitidine hydrochloride-based samples were prepared: three containing form I and II ranitidine hydrochloride and microcrystalline cellulose (spanning the ranges 0-10%, 90-100% and 0-100% form I fraction of total ranitidine hydrochloride), and a fourth group comprising form I ranitidine hydrochloride (0-10%) spiked commercial formulation. Transmission and conventional Raman spectroscopic measurements were recorded from both capsules and tablets of the four sample groups. Prediction models for polymorph and total ranitidine hydrochloride content were more accurate for the tablet than for the capsule systems. TRS was found to be superior to conventional backscattering Raman spectroscopy in the prediction of polymorph and total ranitidine hydrochloride content. The prediction model calculated for form I content across the 0-100% range was appropriate for process control [ratio of prediction to deviation (RPD) equal to 14.62 and 7.42 for tablets and capsules, respectively]. The 10% range calibrations for both form I and total ranitidine hydrochloride content were sufficient for screening (RPDs greater than 2.6). TRS is an effective tool for polymorph process control within the pharmaceutical industry.

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“…In most reported solubility data, a van't Hoff plot is presented as a straight or almost-straight line, and it is not uncommon to find implicit or explicit statements that a van't Hoff plot should yield a straight line, i.e. that the van't Hoff enthalpy of solution is independent of temperature [22]. However, it can be shown [6] that the full thermodynamic interpretation of the van't Hoff enthalpy of solution is given by:…”

Section: Solubility Temperature Dependencementioning

confidence: 99%

Thermodynamics of fenoxycarb in solution

Kuhs

Svärd

Rasmuson

2013

The Journal of Chemical Thermodynamics

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The solubility of fenoxycarb has been determined between 278 and 318 K in several organic solvents. The solid phase at equilibrium and some indication of polymorphism has been properly examined by powder XRD, DSC, Raman and ATR-FTIR spectroscopy, solution 1 H NMR and SEM. Using literature data the activity of the solid phase within a Raoult's law definition has been calculated, based on which solution activity coefficients have been estimated. In ethyl acetate, the van't Hoff enthalpy of solution is constant over the temperature range and equals the melting enthalpy. However, it is shown that the solution is slightly non-ideal with the heat capacity difference term compensating for the activity coefficient term. In toluene, the van't Hoff enthalpy of solution is constant as well but clearly higher than the melting enthalpy. In methanol, ethanol and isopropanol, van Hoff curves are strongly non-linear, the slope however clearly approaching the melting enthalpy at higher temperatures. In all solvents, positive deviations from Raoult's law are prevailing. The activity coefficients follow a decreasing order of isopropanol > ethanol > methanol > toluene > ethyl acetate, and in all solvents decrease monotonically with increasing temperature. The highest activity coefficient is about 18 corresponding to about 2.5 kJ/mol of deviation from ideality.

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Solubility, dissolution rate and phase transition studies of ranitidine hydrochloride tautomeric forms

Cited by 63 publications

References 10 publications

Removal of drugs in aqueous systems by photoassisted degradation

Removal of drugs in aqueous systems by photoassisted degradation

Pharmaceutical polymorphs quantified with transmission Raman spectroscopy

Thermodynamics of fenoxycarb in solution

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