Bromate Solutions of bromates acidified with nitric acid 1 in 20yield a white, crystalline precipitate with the addition of 2 or 3 drops of silver nitrate TS, which dissolves by heating. A pale yellow precipitate is produced with the addition of 1 drop of sodium nitrite TS.
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Abstract Photostability studies of drugs and drug products are an integral part of the product development process in the pharmaceutical industry. These studies are carried out to ensure quality, efficacy, and safety of the formulated products during manufacture, storage, and use.
This review deals with the concept of photostability and related aspects and the literature available in the field. It highlights the role of the photochemistry in the photostability studies, describes the functional groups important for the photoreactivity of drugs, explains photophysical processes, and deals with the kinetics of photochemical reactions.
The various modes of photodegradation of drugs with examples of selected compounds are presented. The biological consequences of the effect of light on the drug degradation are described.
The photostability testing of drugs and drug products and the requirements under ICH guideline are discussed.
Some information on the packaging requirements for the formulated products is provided. The various methods used for the photostabilization of solid and liquid dosage forms are also discussed. Introduction A large number of drugs are sensitive to light [ 12 ] and therefore their formulated products may degrade during manufacturing, storage, and administration.
This may result in potency loss, altered efficacy, and adverse biological effects. The European Pharmacopoeia [ 3 ] prescribes light protection for more than drugs and Spectrophotometric determination of ascorbic acid concentration. Knowledge of the photochemical behavior of drugs can provide guidance for handling, packaging, and labeling of drug products.
The use of the appropriate containers and packaging material can protect the products from the deleterious effects of light. The sensitivity of a drug to a particular spectral region of light may vary with its chemical structure, photoreactivity, and nature of the dosage form. The study of the photochemical reactions may provide information on the mode of stabilization of the active ingredients in a product.
These reactions are often complex and involve free radical species that form photoproducts [ 4 — 6 ]. Photosensitized reactions may also lead to the degradation of the drug substances [ 6 ]. The photoproducts of a drug may be harmful and cause phototoxic, photoallergic, or photosensitization reactions upon administration [ 7 — 9 ].
These reactions may also be initiated by the interaction of a drug with endogenous substances in the body in the presence of light. The evaluation of the photochemical stability of drugs and drug products is an essential component of the formulation development process in the pharmaceutical industry.
Several monographs [ 10 — 12 ], details [ 13 — 23 ], and reviews [ 24 — 29 ] have been published on the photochemistry, photostability, and related aspects of the drugs and drug products.
Information on the photosensitivity, photostability, and storage of pharmaceuticals is also provided in the pharmacopoeias [ 1 — 3 ] and other literature [ 143031 ]. Photostability The photostability of a drug substance may be defined as the response of the drug or drug product to the exposure to solar, UV, and visible light in the solid, semisolid, or liquid state that leads to a physical or chemical change.
The response of the drug to light absorption and excitation can be considered in terms of photodegradation photolysis reactions through the formation of free radicals or photosensitization reactions by intermolecular energy transfer.
These reactions involve primary photochemical and secondary chemical reactions that give the final products. Objectives of the Photostability Studies In view of the photosensitivity and photoinstability of drugs and adjuvants, knowledge of the photostability of these substances and their formulated products is necessary to evaluate the following: Requirements for the Photostability Studies Consider the following: Photochemical Reactions The photochemistry of the organic compounds has been studied for a long time [ 32 — 36 ] and an advanced treatment of this subject is available [ 637 ].
The study of the photochemistry provides a basis for the understanding of the photochemical reactions of the drug substances that affect their stability and efficacy. Photochemical reactions may lead to the degradation of the drug substances by one or more pathways to form different products.
The elucidation of the mechanisms of these pathways requires a thorough understanding of the nature and type of the photochemical reactions involved.
These would largely depend on the presence of certain functional groups, physical characteristics light absorption,solubility, etc. The assessment of the photostability of the drug substances is based on the study of all those factors that determine the rates and mechanisms of the underlying photochemical reactions.
Spectral Regions of the UV, Visible, and Solar Radiation The spectral regions of the UV, visible, and solar light involved in the photochemical reactions are as follows: Chemical Groups Important for the Photoreactivity of the Drug Molecules The presence of the following chemical functional groups in the drug molecules [ 10 ] is usually necessary for the occurrence of photochemical reactions: Photophysical Processes It is necessary to understand the various photophysical processes involved in the absorption and dissipation of the light energy see 1 — 7 that have been described by Moore [ 38 ].
These may be followed by additional reactions forming free radicals and subsequently the final products see 8 — 11as a result of the photodegradation of the drug substances.ISONIAZID International Programme on Chemical Safety Poisons Information Monograph Pharmaceutical 1. NAME Substance Isoniazid Group Tuberculocidal.
1" " ASCORBICACIDMETHODFORPHOSPHORUS(DETERMINATION(Written’by’Pamela’Doolittle,’University’of’Wisconsin6Madison,’[email protected]’’. Sulfur dioxide dissolves fairly readily in water to give a rather complicated reaction mixture, strongly dependent on concentration, temperature and pH (Senning, ).Therefore, the concentration of each of the different forms is a function of the pH medium and is determined by the equilibrium constants K 1 ( × 10 −2 mol dm −3) and K 2 ( × 10 −7 mol dm −3).
Phytonadione is a family of phylloquinones that contains a ring of 2-methyl-1,4-naphthoquinone and an isoprenoid side chain. Members of this group of vitamin K 1 . Photostability studies of drugs and drug products are an integral part of the product development process in the pharmaceutical industry.
These studies are carried out to ensure quality, efficacy, and safety of the formulated products during manufacture, storage, and use.
This review deals with the concept of photostability and related aspects and the literature available in the field. The detection limit of ascorbic acid is 40 μg L −1 and the method obeys Beer's law over the concentration range of – μg mL −1. The proposed method was successfully applied for the determination of ascorbic acid in various samples.