Erythromycin dihydrate

The x-ray powder diffraction patterns of erythromycin dihydrate and anhydrate are shown in Table II. Radiation Cr/V, X 2.2896.7... 

Fig. 8 Dissolution behavior of erythromycin dihydrate, monohydrate, and anhydrate in phosphate buffer (pH 7.5) at 37°C. (From Ref 1)...

Erythromycins. Erythromycin A (14, R = OH, R = CH3, R" = H), the most widely used macroHde antibiotic, was the principal product found in culture broths of Streptomjces eTythreus (39), now reclassified as Saccharopoljspora eythraea (40). It contains a highly substituted aglycone, erythronoHde A, (16, R = R = OH) to which desosamine (1, R = OH, R = H) and cladinose (8, R = CH ) are attached (41). The complete stereochemistry of erythromycin A was estabUshed by x-ray analysis of its hydroiodide dihydrate (42) total synthesis of erythromycin A was a landmark achievement (43), a task previously considered hopeless (44). 

Temperature-mediated transformations also occur. Ali et al. collected simultaneous Raman spectra and DSC curves of satmeterol xinafoate, detecting two forms [250]. Raman spectroscopy was used to follow the conversions of erythromycin A dihydrate as a function of temperature conditions were identified where the Raman data provided more insights into the kinetics than powder XRD [251]. 

I. Miroshnyk, L. Khriachtchev, S. Mirza, J. Rantanen, J. Heinamaki and J. Yliruusi, Insight into thermally induced phase transformations of erythromycin A dihydrate, Cryst. Growth Des., 6, 369-374 (2006). 

Erythromycin A, a widely used, macrolide, antibiotic substance, was crystallized as the hydriodide dihydrate. It would be expected that the iodine atom would be used as the heavy atom in solving the structure, and, indeed, the authors tried the heavy-atom method first.68 Unfortunately, the iodine atom lies on a crystallographic mirror-plane, and so this method failed. Because erythromycin con-... 

Dibasic calcium phosphate dihydrate should not be used to formulate tetracycline antibiotics.Dibasic calcium phosphate dihydrate has been reported to be incompatible with indomethacin aspirin,aspartame, ampicillin, cephalexin,and erythromycin. The surface of dibasic calcium phosphate dihydrate is alkaline and consequently it should not be used with drugs that are sensitive to alkaline pH. 

Solid-state NMR has been used extensively for characterizing the structures of N-desmethylnefopam HC1 (38), patellin (39), erythromycin A dihydrate (40), and the amorphous nature of ursodeoxycholic acid (41). The conformations of 3 -amino-3 -deoxythymidine (42), gramicidin A (43), and amiodarone HC1 (44) have been confirmed by solid-state NMR. 

GA Stephenson, JG Stowell, PH Toma, RR Pfeiffer, SR Byrn. Solid-state investigations of erythromycin A dihydrate Structure, NMR spectroscopy, and hygroscopic-ity. J Pharm Sci 86 1239-1244, 1997. 

A large number of solvates have been reported, especially for steroids and antibiotics. It has been observed that cortisone acetate and dexamethasone acetate can be crystallized as 10 different solvates. Dirithromycin, a semisynthetic macrolide antibiotic, crystallizes in two anhydrous polymorphic forms and in at least nine stoichiometric solvate forms. Six of the known solvates are isomorphic, having nearly identical x-ray powder diffraction patterns [76]. In addition to the anhydrate and dihydrate, erythromycin also forms solvates with acetone, chloroform, ethanol, n-butanol, and/-propanol [77]. 

Erythromycin Heating the dihydrate for 2 hours at 135°C in an oven, and then coohng to room temperatine [152,153]... 

Since the mid-1970s, a number of exceptions to the general rule have been found. For example. Fig. 8 shows that the hydrate phases of erythromycin exhibit a reverse order of solubility where the dihydrate phase exhibits the fastest dissolution rate and the highest equilib-... 

Dissolution profiles of erythromycin anhydrate ( -), monohydrate and dihydrate (- ). (The plots were adapted from data originally presented in Ref 76.)... 

Erythromycin base is reported to exist in a number of structural forms, including an anhydrate, a dihydrate, and an amorphous form [109, 110]. The commercially available product appears to be a partially crystalline material, containing a significant amount of amor-... 

Rdmer, M., Heinamaki, J., Miroshnyk, I., Sandler, N., Rantanen, J. and Yliruusi, J. Phase transformations of erythromycin A dihydrate during pelletization and drying. Eur. J. Pharm. Biopharm. 67 246-252, 2007. 

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