Solid-State Stability Profiling of Ramipril to Optimize Its Quality Efficiency and Safety

High global expenditure on out-of-label-date drugs, along with safety concerns associated with the accumulation of degradation impurities, justify the need for stability profiling. In this article, a comprehensive study on the solid-state stability of ramipril (RAM) was performed via isothermal methods under stress conditions. A validated stability-indicating HPLC protocol was used. The effects of various factors on the rate of RAM degradation were investigated, including: temperature, relative air humidity (RH), excipients (talc, starch, methylcellulose and hydroxypropyl methylcellulose), mode of tablet storage, and immediate packaging. The degradation impurities were also identified by HPLC–MS. It was found that RAM was unstable, and temperature accelerated its degradation. RAM was also vulnerable to RH changes, suggesting that it must be protected from moisture. The reaction followed first-order kinetics. The studied excipients stabilized RAM as a pure substance. The tableting process deteriorated its stability, explaining the need for appropriate immediate packaging. RAM in the form of tablets must be stored in blisters, and it cannot be crushed into two halves. The degradation impurities were ramiprilat and the diketopiperazine derivative.

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Ring-Opening Polymerization of ε-Caprolactone Using Novel Tin(II) Alkoxide Initiators

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.55-57.757 ◽

2008 ◽

Vol 55-57 ◽

pp. 757-760 ◽

Cited By ~ 4

Author(s):

A. Kleawkla ◽

Robert Molloy ◽

W. Naksata ◽

Winita Punyodom

Keyword(s):

Solid State ◽

Rate Constants ◽

Ring Opening ◽

Ring Opening Polymerization ◽

Zero Order ◽

Molecular Aggregation ◽

First Order ◽

First Order Kinetics ◽

Zero Order Kinetics ◽

Kinetics Of

Two novel tin(II) alkoxides, namely: tin(II) hexoxide, Sn(OC6H13)2, and tin(II) octoxide, Sn(OC8H17)2, have been synthesized for use as coordination-insertion initiators in the bulk ring-opening polymerization of ε-caprolactone. The kinetics of the polymerization reactions were studied at 140 °C by dilatometry. It was found that both alkoxides were slow to dissolve in the ε-caprolactone monomer due to their molecular aggregation in the solid state. As a result, the slow solubilization of the initiators gave rise to deviations from the expected first-order kinetics. Instead, the kinetic results adhered more closely to zero-order kinetics with apparent zero-order rate constants k0 of 6.58 x 10-2 and 4.63 x 10-2 mol l-1 min-1 for the hexoxide and octoxide respectively

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Studies on photocatalytic activity of the synthesised TiO2 and Ag/TiO2 photocatalysts under UV and sunlight irradiations

Water Science & Technology ◽

10.2166/wst.2011.231 ◽

2011 ◽

Vol 63 (3) ◽

pp. 377-384 ◽

Cited By ~ 10

Author(s):

R. Vaithiyanathan ◽

T. Sivakumar

Keyword(s):

Uv Light ◽

Sol Gel ◽

Solar Light ◽

Light Sources ◽

Tio2 Photocatalysts ◽

First Order ◽

First Order Kinetics ◽

Radiation Sources ◽

Silver Metal ◽

Comprehensive Study

Photocatalytic decolorisation and degradation of Reactive Red 120 (RR 120) has been investigated under UV (365 nm) and solar light as radiation sources using synthesised nano titania catalyst prepared via sol-gel method. The study encompassed calcination of synthesised titania catalyst at a range of temperature up to 1,000°C. The effects of calcination temperature on titania catalyst have been evaluated on the decolorisation of RR 120. The analysis revealed complete decolorisation of dye solution in 100 min under UV light with the TiO2 catalyst calcined at 200°C. Only a maximum of 47% dye decolorisation was achieved under sunlight in 4 h with no improvement even after prolonged irradiation. In an endeavour to improve the catalytic activity, bare titania was modified with silver metal and a comprehensive study on the characteristics of silver modified catalyst was made. The result was an enhancement of the rate of decolorisation of dye under both UV and solar light sources. All the catalysts were characterised by XRD and BET analyses. Optimisation of the degradation of RR 120 has been carried out using the unmodified catalyst by varying the amount of catalyst, substrate concentration, pH of dye solution. Effects of addition of small amounts of various oxidants such as H2O2, KBrO3 and (NH4)2S2O8 have also been studied. Pseudo first order kinetics was observed in the photocatalytic decolorisation of dye. The mineralisation of RR 120 was monitored by TOC analysis.

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Phosphinsubstituierte Chelatliganden, XX [1] Darstellung und diastereoselektive Komplexierung von chiralen Phosphinothioformamiden, Ph2P(X)C(S)NHCHMePh (X = 2 e- , O, S) / Phosphine-Substituted Chelate Ligands, XX [1] Synthesis and Diastereoselective Complexation of Chiral Phosphinothioformamides, Ph2P(X)C(S)NHCHMePh (X = 2e-, O, S)

Zeitschrift für Naturforschung B ◽

10.1515/znb-1986-0914 ◽

1986 ◽

Vol 41 (9) ◽

pp. 1142-1150 ◽

Cited By ~ 5

Keyword(s):

Free Energy ◽

Solid State ◽

Chelate Complexes ◽

Metal Centre ◽

First Order ◽

First Order Kinetics ◽

Free Energy Of Activation ◽

Optical Induction ◽

Optically Pure ◽

High Stereoselectivity

Abstract The am bidentate chiral phosphinothioform am ides (-)-S- and (+)-R-Ph2P(X)C(S)NHCHMePh with X = 2e- (1a). O (1b), S (1c) were obtained from optically pure S- and R -l-phenylethylamine via the isothiocyanate interm ediates. Coordination of (-)-la to CpM(CO)3Cl(M = Mo, W) and ClMn(CO)5 in methanol proceeds with high stereoselectivity forming the P.S-chelate complexes (+)-2a (Mo), (+)-3a (W) and (-)-4a (Mn) which maintain their configuration in solid state. In solution, how ever, the primary diastereom ers 2aA and 3aA epimerize to 2aB and 3aB with inverted configuration at the metal centre. The equilibrial ratio of B /A ≥ 1 (40 °C) indicates only a slight optical induction. The epimerization rate was determined by polarimetry and follow s a formal first-order kinetics with an average free energy of activation ΔḠ* = 92 ± 5 kJ - mol-1 at 20-40 °C. The N .S-chelates (-)-2b, (-)-3b derived from the P-oxide (-)-lb are configurationally stable up to 80 °C suggesting both a kinetic and thermodynamic preference of the A diastereomer. The enantiomeric complexes (-)-2a, (-)-3a, (+)-2b, (+)-3b obtained from Rconfigurated (+)-la, b display mirror-symmetrical CD plots. In contrast to -1a, b, the P-sulfide 1c does not show any selectivity during coordination to the S.S-chelates 2c and 3c.

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A kinetic study of Zn halide/TBAB-catalysed fixation of CO2 with styrene oxide in propylene carbonate

Green Processing and Synthesis ◽

10.1515/gps-2019-0042 ◽

2019 ◽

Vol 8 (1) ◽

pp. 719-729 ◽

Cited By ~ 1

Author(s):

Abdul Rehman ◽

M.F.M. Gunam Resul ◽

Valentine C. Eze ◽

Adam Harvey

Keyword(s):

Propylene Carbonate ◽

Styrene Oxide ◽

Activation Parameters ◽

Green Solvent ◽

Acid Base ◽

First Order ◽

First Order Kinetics ◽

Thermodynamic Activation Parameters ◽

Styrene Carbonate ◽

Comprehensive Study

Abstract Synthesis of styrene carbonate (SC) via the fixation of CO2 with styrene oxide (SO) has been investigated using a combination of zinc bromide (ZnBr2) and tetrabutylammonium halides (TBAX) as acid-base binary homogeneous catalysts. The combination of ZnBr2 and TBAB had a synergistic effect, which led to about 6-fold enhancement in the rate of SC formation as compared to using TBAB alone as a catalyst. Propylene carbonate (PC) was chosen as a green solvent for a comprehensive study of reaction kinetics. The reaction followed a first-order kinetics with respect to SO, CO2, and TBAB, whereas a fractional order was observed for the ZnBr2 when used in combination with the TBAB. Arrhenius and Eyring’s expressions were applied to determine the kinetic and thermodynamic activation parameters, where activation energy (Ea) of 23.3 kJ mol−1 was obtained for the SC formation over the temperature range of 90-120°C. The thermodynamic analysis showed that positive values for enthalpy (ΔH‡ = 18.53 kJ mol−1), Gibbs free energy (ΔG‡ = 79.74 kJ mol−1), whereas a negative entropy (ΔS‡ = –162.88 J mol−1 K−1) was obtained. These thermodynamic parameters suggest that endergonic and kinetically controlled reactions were involved in the formation of SC from SO and CO2.

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The influence of hydrophylic polymers on the release rate of calcium dobesilate in hydrogel formulation assessed in vitro using porcine ear skin

Current Issues in Pharmacy and Medical Sciences ◽

10.1515/cipms-2015-0076 ◽

2015 ◽

Vol 28 (4) ◽

pp. 225-230 ◽

Cited By ~ 1

Author(s):

Dorota Wojcik-Pastuszka ◽

Anna Lisik ◽

Maria Twarda ◽

Ryszard Berkowski ◽

Witold Musial

Keyword(s):

Release Rate ◽

Hydroxypropyl Methylcellulose ◽

Zero Order ◽

Kinetics Model ◽

Calcium Dobesilate ◽

First Order ◽

Anionic Polymers ◽

First Order Kinetics ◽

Zero Order Kinetics

Abstract A shortage of available experimental data exists in the available bibliography on the release rate of calcium dobesilate (CD) from hydrogel formulations. Thus, the aim of the study was to evaluate the effect of selected hydrophilic nonionic polymers and anionic polymers on the release rate of CD from formulation provided for dermal application, as compared to the reference product in the market. The work utilized excised pork skin, while, Methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), and anionic polymers (copolymers of acrylic acid) were used as CD carriers. The release study was executed by the pharmacopoeial paddle method, with extraction cells and fresh excised porcine skin as a membrane. CD in aqueous acceptor fluid was quantified by UV-VIS spectrometry at 300 nm. Subsequently, the kinetic curves were fitted to a zero-order kinetics model, a first-order kinetics model, a second-order kinetics model, as well as to the Higuchi model. The work saw that porcine ear skin influences the release pattern of the CD, compared to the artificial membrane. In the study, the evaluated formulations with MC, polyacrylic acid (PA) and polyacrylate crosspolymer 11 (PC-11) deliver over 60% of the active component (AC), within 250 min, through the excised porcine ear skin, to the acceptor compartment. Moreover, the release observed via porcine ear skin to the aqueous acceptor compartment is congenial to zero-order or first-order kinetics. In addition, the formulations prepared on the basis of MC and PA appear to control AC delivery, independently of actual concentration of AC.

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Visco-elastic changes of vocal fold mucosa related to high and low relative air humidity

Clinical Otolaryngology ◽

10.1046/j.1365-2273.2000.00358-27.x ◽

2000 ◽

Vol 25 (4) ◽

pp. 329-330

Author(s):

R.J.B. Hemler ◽

G.H. Wieneke ◽

P.H. Dejonckere

Keyword(s):

Vocal Fold ◽

Air Humidity ◽

Relative Air Humidity

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Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽

10.32964/tj17.03.167 ◽

2018 ◽

Vol 17 (03) ◽

pp. 167-178 ◽

Cited By ~ 2

Author(s):

Xin Tong ◽

Jiao Li ◽

Jun Ma ◽

Xiaoquan Chen ◽

Wenhao Shen

Keyword(s):

Degradation Rate ◽

Southern China ◽

Catalytic Degradation ◽

Pulp And Paper ◽

Gaseous Pollutants ◽

Pulp And Paper Mills ◽

Paper Mills ◽

Initial Concentration ◽

First Order ◽

First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

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Clinical, epidemiological and climatic factors related to the occurrence of cutaneous leishmaniasis in an endemic area in northeastern Brazil

Brazilian Journal of Biology ◽

10.1590/1519-6984.224937 ◽

2020 ◽

Author(s):

R. S. Oliveira ◽

K. B. A. Pimentel ◽

M. L. Moura ◽

C. F. Aragão ◽

A. S. Guimarães-e-Silva ◽

...

Keyword(s):

Cutaneous Leishmaniasis ◽

Climatic Factors ◽

Wide Distribution ◽

Northeastern Brazil ◽

Public Health Issue ◽

Air Humidity ◽

Disease Occurrence ◽

Relative Air Humidity ◽

Age Range ◽

And Control

Abstract Cutaneous leishmaniasis (CL) is a neglected tropical disease with a wide distribution in the Americas. Brazil is an endemic country and present cases in all states. This study aimed to describe the occurrence, the underlying clinical and epidemiological factors, and the correlation of climatic variables with the frequency of reported CL cases in the municipality of Caxias, state of Maranhão, Brazil. This is a retrospective and descriptive epidemiological study based on data extracted from the Brazilian Information System of Diseases Notification, from 2007 to 2017. Maximum and minimum temperature, precipitation, and relative air humidity data were provided by the Brazilian National Institute of Meteorology. A total of 201 reported autochthonous CL cases were analyzed. The predominance of cases was observed in males (70.1%). The age range between 31 and 60 years old was the most affected, with 96 cases (47.9%). Of the total number of registered cases, 38.8% of the affected individuals were engaged in agriculture-related activities. The georeferenced distribution revealed the heterogeneity of disease occurrence, with cases concentrated in the Western and Southern regions of the municipality. An association was detected between relative air humidity (monthly mean) and the number of CL cases per month (p = 0.04). CL continues to be a concerning public health issue in Caxias. In this context, there is a pressing need to strengthen measures of prevention and control of the disease through the network of health services of the municipality, considering local and regional particularities.

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Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

10.31221/osf.io/m9g7p ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Methyl Orange ◽

Solution Ph ◽

Vanadium Concentration ◽

Limiting Behavior ◽

First Order ◽

First Order Kinetics ◽

Ph Range ◽

Kinetic Pattern ◽

Triton X ◽

Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

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Biodegradation rates of aromatic contaminants in biofilm reactors

Water Science & Technology ◽

10.2166/wst.1995.0027 ◽

1995 ◽

Vol 31 (1) ◽

pp. 117-128 ◽

Cited By ~ 8

Author(s):

Jean-Pierre Arcangeli ◽

Erik Arvin

Keyword(s):

Aromatic Hydrocarbons ◽

Competitive Inhibition ◽

Removal Rate ◽

First Order ◽

Biofilm Reactors ◽

First Order Kinetics ◽

Reducing Conditions ◽

Low Concentrations ◽

Degradation Rates ◽

Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

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