Polymorphism: an evaluation of the potential risk to the quality of drug products from the Farmácia Popular Rede Própria

Polymorphism in solids is a common phenomenon in drugs, which can lead to compromised quality due to changes in their physicochemical properties, particularly solubility, and, therefore, reduce bioavailability. Herein, a bibliographic survey was performed based on key issues and studies related to polymorphism in active pharmaceutical ingredient (APIs) present in medications from the Farmácia Popular Rede Própria. Polymorphism must be controlled to prevent possible ineffective therapy and/or improper dosage. Few mandatory tests for the identification and control of polymorphism in medications are currently available, which can result in serious public health concerns

Relationships between structural and thermal properties of anhydrous and solvated crystalline forms of brodimoprim

The isolation and physicochemical characterization of four crystalline modifications of brodimoprim (5-[(4-bromo-3,5-dimethoxyphenyl)methyl]-2,4-pyrimidinediamine, hereinafter BMP), a structural analog of trimethoprim (TMP), are reported. These phases include an unsolvated form of BMP, a hemihydrate (BMP0.5H2O), a 1:1 solvate containing isopropanol (BMPC3H7OH(iso)), and a hemichloroformate (BMP0.5CHCl3). Unsolvated BMP was isolated both by recrystallization from a range of common solvents as well as by thermal decomposition of the above solvates and no evidence for polymorphism was found. PXRD data indicated that the three solvates crystallize in different arrangements. Data from thermal analysis (thermogravimetry (TGA), hot stage microscopy (HSM), differential scanning calorimetry (DSC)) of the solvates containing water and iso-propanol were interpreted on the basis of their singlecrystal X-ray structures which revealed that the modes of solvent inclusion in BMP0.5H2O and BMPC3H7OH(iso) may be described as ‘isolated site’ and ‘lattice channel’ type inclusions, respectively

Lisinopril dihydrate: single-crystal X-ray structure and physicochemical characterization of derived solid forms

Screening for new solid forms of the antihypertensive lisinopril was performed by recrystallization of the commercial form, lisinopril dihydrate, from various solvents and by exposing the product of its dehydration to a series of vapors under controlled conditions. Modifications other than the dihydrate encountered in the study included new anhydrous and amorphous forms, with intrinsic dissolution rates significantly greater than that of the dihydrate. Further physicochemical characterization included constant and programmed temperature powder X-ray diffraction, differential scanning calorimetry, thermogravimetry, and Fourier transform infrared spectroscopy. In the course of this study, the single-crystal X-ray structure of lisinopril dihydrate, [a = 14.550(2), b = 5.8917(8), c = 14.238(2) Å, β = 112.832(3)° at T = 173(2) K, space group P21 , Z = 2], was determined for the first time, revealing its double zwitterionic character in the solid state

The crystal and molecular structure of 3,6-di(2-pyridyl)-1,4-dihydro-1,2,4,5-tetrazine

No abstract availabl

Thermal and structural properties of ambroxol polymorphs

The thermal and structural characteristics of two crystal forms of ambroxol, (trans-((amino-2-dibromo-3,5-benzyl)amino)-4-cyclohexanol), a drug with remarkable mucolytic and expectorant properties marketed in several drug products, were investigated. Form II (m.p. 92.4\ub0C) is obtained by spontaneous cooling from a hot water/ethanol solution while Form I (m.p. 99.5\ub0C) slowly separates from the mother liquor. The two forms can be identified by PXRD and DSC analyses. On the basis of both thermal and structural data the thermodynamic relationship of enantiotropy was deduced. No metastable (Form I)stable (Form II) conversion was observed upon storage at ambient conditions. Form I crystallizes in the space group P21/n (alternative setting of P21/c) with Z=8. Form II crystallizes in the space group P21/c with Z=4 and a significantly different crystal packing arrangement from that in Form I. A third crystalline modification, Form III (space group P21/c with Z=16) was detected on cooling a single crystal of Form I down to -70\ub0C. On warming to ambient temperature Form III was found to revert to Form I. This reversible single crystal to single crystal transition was structurally characterised and found to involve subtle changes in the types and extent of molecular disorder as well as the hydrogen bonding arrangement

Structural characterization of two polymorphic forms of piroxicam pivalate

The crystal and molecular structures of two polymorphs of piroxicam pivalate are presented and discussed. A peculiarity of the high melting (154 \ub0C) polymorph is the association of piroxicam pivalate molecules as centrosymmetric dimers by hydrogen bonding. Two centrosymmetrically related N-H\ub7\ub7\ub7N hydrogen bonds maintain the dimer structure involving the amido nitrogen atom as donor and the pyridine nitrogen atom as acceptor. Molecular association of this type does not occur in the crystal structures of drugs belonging to the oxicam class of nonsteroidal antiinflammatory drugs. Two distinct conformations coexist in the crystal of the low melting polymorph (136 \ub0C) with differing hydrogen bonding arrangements within domains of the crystallographically independent molecules. The occurrence of different molecular conformations (conformational polymorphism) associated with different hydrogen bonding schemes in discrete domains is an unusual structural feature. Structural data for the two polymorphs are also correlated with the relevant infrared spectra. Computer-generated X-ray powder diffraction patterns for the two polymorphs of piroxicam pivalate are in very good agreement with the experimental ones, thus confirming the validity of the single-crystal X-ray models