Metronidazole 4- benzoate

Metronidazole benzoate 0.5 g Brilliant green Each ml of 0.1 N HC104 e= 0.02753 g of C13H13N3O4... 

Add metronidazole benzoate and propylene glycol dispersion (step 1) to mixer. 

Hoelgaard, A. and Moller, N. (1983). Hydrate formation of metronidazole benzoate in aqueous suspensions, Int. J. Pharm., 15 213-221. 

P. P. Pashankov and L. L. Kostova, Reversed-phase high-performance liquid chromatography of metronidazole benzoate in suspension dosage form, J. Chromatogr., 394 382 (1987). 

The suspension (unlike the tablets) is made up of metronidazole benzoate. The benzoate must be cleaved by acid in order for the active metronidazole to be absorbed. Thus in neutral acid conditions the metronidazole suspension is likely to be less effective. 

Caira, M.R. Nassimbeni, L.R. van Oudtshoorn B. X-Ray structural characterization of anhydrous metronidazole benzoate and metronidazole benzoate monohydrate. J. Pharm. Sci. 1993, 82, 1006-1009. 

Grant et al. 1984), from which the enthalpy of solution can be calculated from the slope. If the lines intersect, it is known as the transition temperature, and one consequence of this is that there may be a transition from one polymorph to another, depending on the storage conditions. For example, the formation of the monohydrate of metronidazole benzoate from a suspension of the anhydrate was predicted from such data (Holgaard and Moller 1983). 

The instability of many anhydrate phases with respect to water has been long known. For instance, it was shown by Shefter and Higuchi that hydrate phases of cholesterol, theophylline, caffeine, glutethimide, and succinyl sulfathiazole would spontaneously form during dissolution studies [32]. Similar behavior has been reported for metronidazole benzoate [33] and carbamazepine [34]. In each of these systems, the integrity of the anhydrous phases can be maintained only as... 

Hydrates can sometimes be obtained by simply suspending the anhydrous material in water, whereupon a form of Ostwald ripening occurs. For instance, aqueous suspensions of anhydrous metronidazole benzoate are metastable, and storage at temperatures lower then 38°C leads to monohydrate formation accompanied by crystal growth [65]. Sorbitol provides another example of this behavior, where slow cooling of a saturated aqueous solution yields long thin needles of sorbitol hydrate [66]. When suspended in water, anhydrous carbamazepine is transformed to carbamazepine dihydrate [67]. In other instances, hydrates can be obtained from mixed solvent systems. 

A monohydrate phase of metronidazole benzoate exhibited solubility properties different from those of the commercially available anhydrous form [37], The monohydrate was found to be the thermodynamically stable form in water below 38°C. The enthalpy and entropy changes of transition for the conversion of the anhydrate to the monohydrate were determined to be -1200 cal/mol and -3.7 cal/K mol, respectively. This transition was accompanied by a drastic increase in particle size and caused physical instability of oral suspension formula-... 

A similar conclusion was reached regarding the relative stability of the monohydrate and anhydrate phases of metronidazole benzoate [37]. The enthalpy term (-1.20 kcal/mol) favored conversion to the monohydrate, but the strong entropy term (-3.7 cal/K mol) essen-... 

El-Kamel, A. H., Ashri, L. Y, Alsarra, I. A. (2007). Micromatricial metronidazole benzoate film as a local mucoadhesive delivery stem for treatment of periodontal diseases, AAPS Pharm. Sci. Tech., 8, E75/1-E75/11. 

Gellan-chitosan polyelectrolyte complex beads, prepared by solution extruding method, have been explored for their potential application in delivery of metronidazole and metronidazole benzoate to the gastrointestinal tract [89]. 

R. Patel, B. Dadhani, R. Ladani, A.Ft. Baria and J. Patel, Formulation, evaluation and optimization of stomach specific in situ gel of clarithromycin and metronidazole benzoate, Int. J. DrugDeliv.2, 2 141-153, 2010. 

Zamani M, Morshed M, Varshosaz J, Jannesari M (2010) Controlled release of metronidazole benzoate from poly epsilon-caprolactone electrospun nanofibers for periodontal diseases. Eur J Pharm Biopharm 75 179-185... 

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