Biomedical subjects

Javier A Ellena

Publications and source records attributed to Javier A Ellena.

6 recordsLinked to original sources

PubMed2006

Polymorphism on leflunomide: stability and crystal structures.

Two polymorphs of Leflunomide were found and studied (form I and II). Both of them were characterized by X-ray powder diffraction and thermal analysis. Single crystals were obtained and both structures were solved. Forms I and II crystallize in the space group P2(1)/c with two and one independent molecules per asymmetric unit, respectively. Thermodynamic stability of the two forms is assessed by differential scanning calorimetry. The cohesion in the crystal of form I (the more stable) is provided by both by H bonding as well as pi...pi interactions, while in form II it is given only by the former. The independent molecules in form I adopt different conformations thus allowing for a larger number of intermolecular interactions.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2004

The Zn2+ salt of pamidronate: a role for water in the metal-cation binding properties of bisphosphonates.

Pamidronate (3-ammonium-1-hydroxypropylidene-1,1-bisphosphonate) is used clinically in the treatment of diseases affecting bone tissue. In the salt zinc pamidronate dihydrate, Zn(2+).2C(3)H(10)NO(7)P(2)(-).2H(2)O, pamidronate is a zwitterion with an overall charge of -1. The carbon chain adopts a trans conformation, separating maximally the positively charged N atom from the negative phosphonate groups. The Zn(2+) ion lies on an inversion center and is surrounded by a sixfold coordination sphere provided by two bidentate chelating zwitterions and two water molecules. The bidentate O.Zn.O bond angle is 92.70 (7) degrees, while the O.O bite distance is 3.018 (3) A.

Journal Article↗

PubMed2003

Two members of the bisphosphonate class of drugs: a zwitterion and a molecular compound.

The compounds studied in this paper, viz. (1-ammonio-1-phosphonopropyl)phosphonate, C(3)H(11)NO(6)P(2), (I), and 1-(acetylamino)propylidene-1,1-bisphosphonic acid dihydrate, C(5)H(13)NO(7)P(2).2H(2)O, (II), are members of a commonly used family of therapeutic agents. Compound (I) is an inner salt with separated negative (on the ionized PO(3) group) and positive (on the tetrahedral N atom) charges, while (II) possesses neutral phosphonyl groups and one amide N atom. Both structures have a C-C-C-N backbone, which has comparable geometric parameters in (I) and (II); the main difference was found in one of the N-C-P bond angles, which is lengthened in (II) because of an intramolecular O(PO(3))-H.O(C=O) interaction. The hydrogen-bonding scheme in the crystal of (I) includes all possible donor atoms, namely all the H atoms of the ammonium group and the phosphonic acid functions. As a result of these interactions, the zwitterions are organized into a plane running along the crystallographic x axis. In (II), the intermolecular interactions include all possible donor atoms, except for the N atom; the packing differs from that of (I) in that the molecules are arranged in a chain running parallel to the x axis. In the chains, the molecules form head-to-head dimers, while the crystallization water molecules contribute to the intra- and interchain cohesion.

Diphosphonates↗

PubMed2003

17alpha,21-Dihydroxy-16beta-methylpregna-1,4-diene-3,11,20-trione (meprednisone).

The title compound, C(22)H(28)O(5), is a commercial therapeutic agent of the steroid class. Both independent molecules in the asymmetric unit have six-membered A rings that are planar, while the B and C rings adopt normal chair conformations. The five-membered D ring is in a 13beta,14alpha-half-chair conformation, and the B/C and C/D ring junctions are in trans positions. Cohesion in the crystal is provided by O-H.O hydrogen bonds, which generate chains of molecules that are organized in a plane that lies along the crystallographic b axis.

Crystallography, X-Ray↗

PubMed2002

Losartan potassium, a non-peptide agent for the treatment of arterial hypertension.

In the title compound, potassium 2-butyl-4-chloro-1-[[2'-(5-tetrazolido)biphenyl-4-yl]methyl]-1H-imidazol-5-ylmethanol, K(+) x C(22)H(22)ClN(6)O(-), the imidazole and tetrazole rings are at angles of 85.0 (2) and 51.8 (1) degrees, respectively, to the phenyl rings to which they are attached, while the dihedral angle between the latter two rings is 46.7 (1) degrees. The coordination sphere of the metal cation consists of six tetrazoyl N atoms, the methanol O atom and the pi cloud of one of the phenyl rings. These interactions determine the formation of columns of molecular anions that lie parallel to the b axis, while hydrogen bonding contributes to intercolumnar cohesion. Far from the centre of the columns, the hydrocarbon chain is immersed in a hydrophobic environment.

Antihypertensive Agents↗

PubMed2002

Disodium pamidronate.

The title compound, disodium 3-ammonium-1-hydroxypropylidene-1,1-bisphosphonate pentahydrate, 2Na(+).C(3)H(9)NO(7)P(2)(2-).5H(2)O, is used for the diagnosis and treatment of a number of bone disorders. In the solid state, disodium pamidronate shows zwitterionic character and has four different modes of chelation to sodium. The metal is octahedrally coordinated by zwitterion and water O atoms. Both coordination to sodium and hydrogen bonding determine the packing in the crystal, which comprises columns lying parallel to the crystallographic a axis.

Bone Diseases↗