Authors:Sirous Azizi, Afsaneh Dadarkhah, Zahra Rezasoltani, Seyed Ahmad Raeissadat, Reza Kazempoor Mofrad, and Sharif Najafi
features including age, weight, height, and body mass index were recorded for all participants as well. Study intervention The group intervention was instructed to use acetaminophen if needed and to follow lifestyle
scanning calorimetry (DSC) is a thermal analytical tool for preformulation
studies. Extrapolated melting temperature (TP)
and heat of fusion (ΔHf)
can be used as parameters for optimizing the DSC performance. Two model pharmaceuticals
acetaminophen and nicotinamide are used in this study. Using a factorial design
for the experimental model and matrix analysis the results, the effect of
sample mass, heating rate and the nitrogen flow rate were evaluated on the
and TP values. Two
levels for each of the procedural variables were used as a balanced experimental
design with two sample sizes, two heating rates and two nitrogen flow rates.
It was found that the change in the heating rate caused significant changes
in the ΔHf
values but not the Tp
values for acetaminophen. However, no significant effect was found for the Tp value but ΔHf value was affected to a
certain extent for nicotinamide.
Authors:G. Perlovich, Tatyana Volkova, and Annette Bauer-Brandl
The thermodynamic relationship between crystal modifications of paracetamol was studied by alternative methods. Temperature
dependence of saturated vapor pressure for polymorphic modifications of the drug paracetamol (acetaminophen) was mea sured
and thermodynamic functions of the sublimation process calculated. Solution calorimetry was carried out for the two modifications
in the same solvent. Thermodynamic parameters for sublimation for form I (monoclinic) were found: ΔGsub298=60.0 kJ mol−1; ΔHsub298=117.9�0.7 kJ mol−1; ΔSsub298=190�2 J mol−1 K−1. For the orthorhombic modification (form II), the saturated vapor pressure could only be studied at 391 K. Phase transition
enthalpy at 298 K, ΔHtr298(I→II)=2.0�0.4 kJ mol−1, was derived as the difference between the solution enthalpies of the noted polymorphs in the same solution (methanol). Based
on ΔHtr298 (I→II), differences between temperature dependencies of heat capacities of both modifications and the vapor pressure value
of form II at 391 K, the temperature dependence of saturated vapor pressure and thermodynamic sublimation parameters for modification
II were also estimated (ΔGsub298=56.1 kJ mol−1; ΔHsub298=115.9�0.9 kJ mol−1; ΔSsub298=200�3 J mol−1 K−1). The results indicate that the modifications are monotropically related, which is in contrast to findings recently reported
found by classical thermochemical methods.
Transfer of four rapid thin-layer chromatography (TLC) screening methods used to detect substandard and counterfeit pharmaceutical products to quantitative high-performance TLC (HPTLC)-densitometry methods is demonstrated. These methods for acetaminophen, acetylsalicylic acid, ibuprofen, and chlorpheniramine maleate are contained in a Compendium of methods developed by Kenyon and Layloff for use in countries with limited resources. The new quantitative methods use Merck HPTLC silica gel 60 F254 glass plates, automated standard and sample application, and automated densitometry for detection, identification, and quantification. Standard and sample solution preparation and application procedures for obtaining calibration curves and bracketed samples are described. The HPTLC plates give better efficiency, selectivity, and resolution than TLC, and the new methods overcome the deficiencies in technology related to manual application and visual zone comparison that do not allow the Compendium TLC procedures to support regulatory compliance actions. These transferred methods can be fully validated according to International Conference on Harmonization (ICH) guidelines or by interlaboratory studies if their applications require. The approach described can be used to transfer the remaining Compendium methods as well as the GPHF [Global (formerly German) Pharma Health Fund E.V.] Minilab kit TLC screening methods.
Authors:Alan Ramić, Marica Medić-Šarić, Srećko Turina, and Ivona Jasprica
Thin-layer chromatography has been used to investigate possible chemical interactions of vitamins A and D with frequently used therapeutics (estrogens and progestins, corticosteroids, HMG CoA reductase inhibitors, vitamins, and nonsteroidal anti-inflammatory drugs). We also compared our results with biochemical interactions found in the literature. Concentrations of vitamins and drugs applied to the plate were adjusted to mimic the doses usually prescribed in therapy. TLC was performed on 10 cm × 20 cm TLC plates precoated with silica gel 60 F
. The first step was to determine
values for each vitamin and drug using three different mobile phases — cyclohexane-ether, 50 + 50 (
), cyclohexane—ether, 85 + 15 (
), and ethyl acetate. Solutions of vitamins A and D were applied to the plates as 8 mm bands and the investigated drugs were applied as spots. Chromatography was performed in ascending mode. After calculation of
values we used a combination of stationary and mobile phase for which overlapping of the vitamin band and drug spot occurred during chromatogram development. The strength of interaction was measured as a surface below or above the distorted part of the sample band, visible under short wavelength UV light (
= 254 nm) or after exposing the plates to iodine vapor. The chromatograms were documented by use of a Camag Reprostar 3 System.We established the occurrence of chemical interactions between vitamin A and estradiol propionate, tocopherol acetate, ibuprofen, and ketoprofen, and between vitamin D and hydrocortisone, medrox-yprogesterone acetate, norethisterone acetate, aspirin, ketoprofen, and acetaminophen. A clear relationship between chemical and biochemical interactions could not be established.
Authors:László Kóbori, Zoltán Máthé, János Fazakas, Zsuzsanna Gerlei, Attila Doros, Imre Fehérvári, Enikő Sárváry, Erika Hartmann, Andrea Németh, Tamás Mándli, Szabolcs Tóth, László Szőnyi, Zsuzsanna Korponay, Mátyás Kiss, Dénes Görög, and Jenő Járay
Hazai, E., Vereczkey, L., Monostory, K.:
Reduction of toxic metabolite formation of acetaminophen. Biochem. Biophys. Res., 2002,