Photochemical stability of biologically active compounds. III. Mefloquine as a photosensitizer

T√∏nnesen, Hanne Hjorth; Moore, Douglas E.

doi:10.1016/0378-5173(91)90168-n

Cited by 15 publications

(12 citation statements)

References 7 publications

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“…Compounds which have been developed for long-term medication and/or compounds which are administered in a high cumulative dosage are more likely to cause photosensitivity responses in vivo. 1 In this context, the ophthalmic medicaments (ophthalmic drugs), especially those of topical administration, constitute a family of particular risk and deserve interest. These drugs, upon adequate light irradiation, may suffer photo-damage, the quantum yield of phototransformation being a crucial information for predicting phototoxic reactions in vivo.…”

Section: Introductionmentioning

confidence: 99%

Vitamin B₂-sensitised photooxidation of the ophthalmic drugs Timolol and Pindolol: kinetics and mechanism

Criado

Garcı́a

2004

Redox Report

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The kinetics and mechanistic aspects of the riboflavin-photosensitised oxidation of the topically administrable ophthalmic drugs Timolol (Tim) and Pindolol (Pin) were investigated in water-MeOH (9:1, v/v) solution employing light of wavelength > 400 nm. riboflavin, belonging to the vitamin B(2) complex, is a known human endogenous photosensitiser. The irradiation of riboflavin in the presence of ophthalmic drugs triggers a complex picture of competitive reactions which produces the photodegradation of both the drugs and the pigment itself. The mechanism was elucidated employing stationary photolysis, polarographic detection of dissolved oxygen, stationary and time-resolved fluorescence spectroscopy, and laser flash photolysis. Ophthalmic drugs quench riboflavin-excited singlet and triplet states. From the quenching of excited triplet riboflavin, the semireduced form of the pigment is generated, through an electron transfer process from the drug, with the subsequent production of superoxide anion radical (O(2)(*-)) by reaction with dissolved molecular oxygen. Through the interaction of dissolved oxygen with excited triplet riboflavin, the species singlet oxygen (O(2)((1)Delta(g))) is also generated to a lesser extent. Both O(2)(*-) and O(2)((1)Delta(g)) induce photodegradation of ophthalmic drugs, Tim being approximately 3-fold more easily photooxidisable than Pin, as estimated by oxygen consumption experiments.

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Section: Introductionmentioning

confidence: 99%

Vitamin B₂-sensitised photooxidation of the ophthalmic drugs Timolol and Pindolol: kinetics and mechanism

Criado

Garcı́a

2004

Redox Report

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“…Therefore, photophysical and photochemical photosensitizer properties of quinine in an aqueous solution are determined by pH. In aqueous buffer with pH of 7, the maximum peak of quinine absorption is 331 nm, and the maximum fluorescence emission -367 nm(Tonnesen and Moore, 1991;Chudyk et al, 1993). The quinine fluorescence is inhibited by halogen ions according to the sequence: I ->Br -> Cl -.…”

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confidence: 99%

Analytics of Quinine and its Derivatives

Kluska

Marciniuk-Kluska

Prukała

et al. 2015

Critical Reviews in Analytical Chemistry

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The objective of this study was to perform a synthesis and analysis of the most important information on quinine and its derivatives, which are still very important in the treatment of malaria. The analysis of stereoisomers of quinine and its derivatives was conducted using two techniques, high-performance liquid chromatography and capillary electrophoresis. Particularly noteworthy is the technique used for the determination of isotachophoresis, referred to as one of the so-called green chemistry techniques. Particular attention was paid to properties and the use of quinine and its derivatives in the treatment of malaria. The analytical part will supplement knowledge about quinidine, quinine, and cinchonidine, and will contribute to the growth of research on the so-much-needed drugs against malaria.

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“…Among others, these include the method of development, characterization and specification of active or inactive ingredients, safety analysis or routine analysis in quality control, and stability studies. In the solid state, the temperatures required for thermal degradation at a measurable rate are generally far higher than the temperatures existing, even locally, during photolysis (8), so the mechanisms of thermal and photochemical degradation can be expected to differ. On the other hand, it is well known that at high temperature, the chemical reactivity of drug active components, both pure and in the mixture, can be modified, thus leading to uncontrollable reactions with consequent dangerous situations.…”

Section: Introductionmentioning

confidence: 99%

Thermal Stability Investigation and the Kinetic Study of Folnak® Degradation Process Under Nonisothermal Conditions

Jankovi

2010

AAPS PharmSciTech

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Abstract. The nonisothermal degradation process of Folnak ® drug samples was investigated by simultaneous thermogravimetric and differential thermal analysis in the temperature range from an ambient one up to 810°C. It was established that the degradation proceeds through the five degradation stages (designated as I, II, III, IV, and V), which include: the dehydration (I), the melting process of excipients (II), as well as the decomposition of folic acid (III), corn starch (IV), and saccharose (V), respectively. It was established that the presented excipients show a different behavior from that of the pure materials. During degradation, all excipients increase their thermal stability, and some kind of solidsolid and/or solid-gas interaction occurs. The kinetic parameters and reaction mechanism for the folic acid decomposition were established using different calculation procedures. It was concluded that the folic acid decomposition mechanism cannot be explained by the simple reaction order (ROn) model (n= 1) but with the complex reaction mechanism which includes the higher reaction orders (RO, n>1), with average value of =1.91. The isothermal predictions of the third (III) degradation stage of Folnak ® sample, at four different temperatures (T iso =180°C, 200°C, 220°C, and 260°C), were established. It was concluded that the shapes of the isothermal conversion curves at lower temperatures (180-200°C) were similar, whereas became more complex with further temperature increase due to the pterin and p-amino benzoic acid decomposition behavior, which brings the additional complexity in the overall folic acid decomposition process.

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Photochemical stability of biologically active compounds. III. Mefloquine as a photosensitizer

Cited by 15 publications

References 7 publications

Vitamin B₂-sensitised photooxidation of the ophthalmic drugs Timolol and Pindolol: kinetics and mechanism

Vitamin B₂-sensitised photooxidation of the ophthalmic drugs Timolol and Pindolol: kinetics and mechanism

Analytics of Quinine and its Derivatives

Thermal Stability Investigation and the Kinetic Study of Folnak® Degradation Process Under Nonisothermal Conditions

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Photochemical stability of biologically active compounds. III. Mefloquine as a photosensitizer

Cited by 15 publications

References 7 publications

Vitamin B2-sensitised photooxidation of the ophthalmic drugs Timolol and Pindolol: kinetics and mechanism

Vitamin B2-sensitised photooxidation of the ophthalmic drugs Timolol and Pindolol: kinetics and mechanism

Analytics of Quinine and its Derivatives

Thermal Stability Investigation and the Kinetic Study of Folnak® Degradation Process Under Nonisothermal Conditions

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Product

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Vitamin B₂-sensitised photooxidation of the ophthalmic drugs Timolol and Pindolol: kinetics and mechanism

Vitamin B₂-sensitised photooxidation of the ophthalmic drugs Timolol and Pindolol: kinetics and mechanism