Relevant Literature on the Photostability of Specific Drug Substances and Drug Formulations

T√∏nnesen, Hanne Hjorth

doi:10.1201/9781420023596.ax2

Cited by 2 publications

(11 citation statements)

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“…The main hindrance facing a normal development of photokinetics can be traced down to a mathematical impossibility to analytically solve the rate laws of photoreactions ( Mauser et al, 1998 ; Crano and Guglielmetti, 2003 ; Tonnesen, 2004 ; Nakatani et al, 2016 ; Montalti et al, 2020 ; Scaiano, 2020 ; Pianowski, 2022 ). The absence of integrated rate laws has considerably limited photokinetic investigation towards unravelling photoreaction features, offering accessible metric tools to the experimentalist, and/or allowing better control of the reactions, as usually available for thermal kinetic studies.…”

Section: Introductionmentioning

confidence: 99%

On photokinetics under monochromatic light

Maafi

2023

Front. Chem.

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The properties of photokinetics under monochromatic light have not yet been fully described in the literature. In addition, for the last 120 years or so, explicit, handy model equations that can map out the kinetic behaviour of photoreactions have been lacking. These gaps in the knowledge are addressed in the present paper. Several general features of such photokinetics were investigated, including the effects of initial reactant concentration, the presence of spectator molecules, and radiation intensity. A unique equation, standing for a pseudo-integrated rate law, capable of outlining the kinetic behaviour of any photoreaction is proposed. In addition, a method that solves for quantum yields and absorption coefficients of all species of a given photoreaction is detailed. A metric (the initial velocity) has been adopted, and its reliability for the quantification of several effects was proven by theoretical derivation, Runge–Kutta numerical integration calculations and through the model equation proposed. Overall, this study shows that, under monochromatic light, photoreaction kinetics is well described by Φ-order kinetics, which is embodied by a unifying model equation. This paper is aimed at contributing to rationalising photokinetics via reliable, easy-to-use mathematical tools.

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Section: Introductionmentioning

confidence: 99%

On photokinetics under monochromatic light

Maafi

2023

Front. Chem.

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“…In addition to these variations of the absorption coefficients, the possible absorption of the light by other emerging species in the medium due to high concentration (e.g., complexes ( Tonnesen, 2004 ), quenching ( Menzel et al, 2021 )… etc. ), has also been proposed.…”

Section: Resultsmentioning

confidence: 99%

“…The importance of the OSIA in actinometry will be reviewed in Section 3.9 . Incidentally, the OSIA has sometimes been called the overlap integral ( Tonnesen, 2004 ), a terminology that might lead to confusion because the rate is, itself, expressed by an integral (Eq. (1) ), and hence, such a lack of specificity discourages its use.…”

Section: Experimentalsmentioning

confidence: 99%

“…Better control, quantification, and reproducibility of such processes are, therefore, only possible with an adequate description of their photokinetics. Unfortunately, a standard and comprehensive photokinetic approach for reactions performed under polychromatic light has been lacking in the field ( Mauser et al, 1998 ; Tonnesen, 2004 ; Griesbeck et al, 2012 ; Yamada and Yagai, 2019 ; Montalti et al, 2020 ). The kinetics of these photoreactions has no equivalent counterparts for the basic concepts of thermal chemical kinetics, such as established reaction kinetic orders and/or identified integrated rate laws.…”

Section: Introductionmentioning

confidence: 99%

“…Another strategy used a power series expansion of the rate law to simplify the latter to an integrable form. This process is too approximative to deliver accurate results (usually using only the first-order expansion of the power series) ( Tonnesen, 2004 ). One approach introduces a simplifying hypothesis to derive an explicit formula to fit the experimental data.…”

Section: Introductionmentioning

confidence: 99%

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On photokinetics under polychromatic light

Maafi

2024

Front. Chem.

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Since the dawn of photochemistry 150 years ago, photoreactions have been conducted under polychromatic light. However, despite the pivotal role that photokinetics should naturally play for such reactive photosystems, the literature lacks a comprehensive description of that area. Indeed, one fails to identify explicit model integrated rate laws for these reactions, a characteristic type for their kinetic behavior, or their kinetic order. In addition, there is no consensus in the community on standardized investigative tools to evaluate the reactivity of these photosystems, nor are there venues for the discussion of such photokinetic issues. The present work is a contribution addressing some of these knowledge gaps. It proposes an unprecedented general formula capable of mapping out the kinetic traces of photoreactions under polychromatic light irradiation. This article quantitatively discusses several reaction situations, including the effects of initial reactant concentration and the presence of spectator molecules. It also develops a methodology for standardizing actinometers and defines and describes both the spectral range of highest reactivity and the photonic yield. The validity of the model equation has been proven by comparing its results to both theoretical counterparts and those generated by fourth-order Runge–Kutta numerical calculations. For the first time, a confirmation of the Φ-order character of the kinetics under polychromatic light was established.

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Relevant Literature on the Photostability of Specific Drug Substances and Drug Formulations

Cited by 2 publications

References 0 publications

On photokinetics under monochromatic light

On photokinetics under monochromatic light

On photokinetics under polychromatic light

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