Flávio M.S. Carvalho

Thermal analysis of the antiretroviral zidovudine (AZT) and evaluation of the compatibility with excipients used in solid dosage forms.

Modern thermal analysis techniques are frequently used because of their ability to provide detailed information about both the physical and the energetic properties of a substance. In the present work, the thermal decomposition of zidovudine (AZT) was studied using differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry (TG/DTG). Thermal analysis was supplemented using elemental analysis (C, H, and N), infrared (IR) spectroscopy, and X-ray powder diffraction to characterize the solid intermediates products. Volatile products of the thermal decomposition of AZT were studied by a system composed of the TG/DTA coupled gas chromatography/mass spectrometry (GC/MS). The physical-chemical properties and compatibilities of several commonly used pharmaceutical excipients with AZT were evaluated using thermal methods. The results showed that the product originated from the first thermal decomposition stage corresponds to the cleavage followed by elimination of the azide group and consequent formation of thymine. The second event corresponds to thermal decomposition of thymine. TG/DTA-GC/MS system identified thymines decomposition products as furan and 2-furanmethanol like volatile species. Comparison of the thermoanalytical profiles of the mixtures with individual compounds did not give any evidence of interactions.

β-caryophyllene, a dietary cannabinoid, complexed with β-cyclodextrin produced anti-hyperalgesic effect involving the inhibition of Fos expression in superficial dorsal horn

AIMS Evaluate the anti-hyperalgesic effect of the complex containing β-caryophyllene (βCP) and β-cyclodextrin (βCD) in a non-inflammatory chronic muscle pain mice model and investigated its action on superficial dorsal horn of the lumbar spinal cord. MAIN METHODS The βCP-βCD complex were prepared and characterized through the DSC, TG/DTG, FTIR, XRD and SEM. The model of chronic muscle pain was induced by two injections of pH4.0 saline (20μL) into left gastrocnemius 5days apart. After confirming hyperalgesia, male mice were treated with βCP-βCD (10 or 20mg/kg; p.o.) or vehicle (saline 0.9%, p.o.) daily for 9days. 1h after, the mechanical hyperalgesia, muscle withdrawal thresholds and motor performance were evaluated. To evaluate the βCP-βCD action on spinal cord, animals induced with chronic muscle pain were treated with βCP-βCD (20mg/kg; p.o.) or vehicle (saline 0.9%, p.o.) and 90min. after, were perfused, the lumbar spinal cord collected, crioprotected, cut and submitted in an immunofluorescence protocol for Fos protein. KEY FINDINGS The characterization tests indicated that βCP were efficiently incorporated into βCD. The oral treatment with βCP-βCD, at all doses tested, produced a significant (p<0.05) reduction on mechanical hyperalgesia and a significant (p<0.05) increase in muscle withdrawal thresholds, without produce any alteration in force. In addition, βCP-βCD was able to significantly (p<0.05) decrease Fos expression in the superficial dorsal horn. SIGNIFICANCE Thus, βCP-βCD attenuates the non-inflammatory chronic muscle pain in mice and inhibits the Fos expression in the lumbar spinal cord.

Coutinhoite, a new thorium uranyl silicate hydrate, from Urucum mine, Galiléia, Minas Gerais, Brazil

Abstract The new mineral coutinhoite, ideally ThxBa(1-2x)(H2O)y(UO2)2Si5O13⋅H2O, with 0 ≤ x ≤ 0.5 and 0 ≤ y ≤ (2 + x), occurs as a secondary hydrothermal mineral in the Córrego do Urucum granitic pegmatite, Lavra Urucum, Galiléia Co., Minas Gerais, Brazil. Coutinhoite is intimately associated with weeksite, phosphuranylite, meta-uranocircite, and uranocircite on muscovite and microcline. The mineral forms irregular aggregates with very small curved scales, flaky crystals, up to 10 μm long and with a thickness up to about 0.5 μm. Coutinhoite is transparent to translucent and displays a waxy to silky luster; color and streak are yellow. It is non-fluorescent. The hardness is less than 2. It is brittle. Calculated density is 3.839 g/cm3. Coutinhoite is biaxial negative, α 1.620(3), β 1.627(3), γ 1.629(3), 2Vmeas. = 40(5)°, 2Vcalc. = 56.1°, dispersion r < v strong, orientation Y = c. Pleochroism is Z > Y, X yellow. The empirical formula (based on Si + P = 5) is (Th0.30Ba0.19K0.07Ca0.04)Σ0.60(UO2)2.00(Si4.92P0.08)Σ5.00O12.91·2.86H2O. The mineral is orthorhombic, probable space group Cmmb (67). Cell parameters were refined from the powder data: a 14.1676(9), b 14.1935(9), c 35.754(2) Å, V = 7189.7(2) Å3, and Z = 16. It is probably isostructural with weeksite. Both the description and name were approved by the CNMMN-IMA (Nomenclature Proposal 2003-025).

Purification and Characterization of a Natural Brazilian Clay Blend

Clay blends are products used in several industrial sectors, such as petrochemical or pharmaceutical. In this work we describe a natural clay blend occurring in northeastern Brazil. The aim was to purify and investigate their rheological and physical-chemical properties. Foster essays with water and organic solvents were utilized to access the swelling properties of the analyzed sample. Powder X-ray diffractograms (PXRD) were utilized to analyze qualitatively the clay minerals presents in the sample blend. Scanning eletronic microscopy (SEM) and Malvern techniques were used to investigate the sample clay morphology. The purification proceeding allowed separate distinct clay phases with different colors. PXRD analysis demonstrated that each clay phase presents similar structure. SEM and Malvern analysis showed distinct morphology and different size distribution for each clay phase. Our results revealed that the analyzed sample clay may be classified as smectite blend with strong potential for use in pharmaceutical and cosmetic products.

Influence of Alumina Phases on the Molybdenum Adsorption Capacity and Chemical Stability for 99Mo/99mTc Generators Columns

Technetium-99m is the clinically most used radionuclide worldwide. Although many techniques can be applied to separate 99Mo and 99mTc, the most commonly used method is the column chromatography with alumina as stationary phase. However, the alumina nowadays used has limited adsorption capacity of molybdate ions which implies the need to develop or improve materials to produce high specific activity generators. In this paper, alumina was obtained by a solid state method and heat treatments at different conditions. The powders had a microstructure with porous particles of γ, δ, θ and α-Al2O3 phases as well as specific surface area between 36 and 312 m2 g-1. Most interesting results were reached by powders calcined at 900oC for 5 hours which had high chemical stability and a molybdenum adsorption capacity of 92.45 mg Mo per g alumina.