Colourings adverse reactions

The incidence of gastrointestinal side-effects including nausea, vomiting and diarrhoea with nitrofurantoin is as high as 30% with standard microcrystalline formulations and patients should be advised to take the doses with food. Other important but less common adverse reactions include pulmonary fibrosis, peripheral neuropathy and hypersensitivity. Patients should also be warned that nitrofurantoin can colour the urine yellow or brown. 

A) reactions. Other drugs, e.g. antimicrobials, have a tendency to cause allergy and may lead to bizarre (type B) reactions. Ingredients of a formulation, e.g. colouring, flavouring, sodium content, rather than the active drug may also cause adverse reactions. 

In pharmacy, the dyes used are azo dyes, quinoline dyes, tri-phenylmethane and xanthine dyes. They are not recommended in children because many colouring agents, mainly synthetic dyes, have been associated with hypersensitivity and other adverse reactions (gastrointestinal intolerance, dermatological reactions and carcinogenic concerns). Approximately 2-20% of people with asthma are sensitive to aspirin. Cross-reactions to azo dyes such as tartrazine produce similar effects. They have occurred in patients both with and without a history... 

The intrinsic properties of the active substance are difficult to change, but the pharmacist can choose the right excipients and preparation techniques to overcome or decrease the impact of limitations. Although excipients should be pharmacologically inactive, they may cause adverse effects. The European Paediatric Formulation Initiative (EuPFI) project is considering the suitability of excipients for paediatric formulations. The results have been published in the STEP database [13]. For example many colouring agents have been associated with hypersensitivity and other adverse reactions. 

Legislation on colouring agents for medicines follows Food legislation [63] Azo dyes - especially tartrazine — are suspected of adverse reactions. The latest evaluation by the European Food Safety Agency (EFSA) resulted in 2009 in a continuation of the allowance [64]. Nevertheless the UK Foods Standards Agency advices that avoiding of colourants in the diet of hyperactive children may have a beneflcial effect. 

This chapter wiU describe in detail their occurrence in the individual food commodities, their properties, stability and important reactions, their importance in human nutrition and physiology and their use as food colourings in food technology. A section of the chapter is devoted to the so-called enzymatic browning reactions that proceed as desirable, but also as adverse reactions in many foods of plant origin. Substances used as colour additives are described in Chapter 11, which focuses on food additives. Reaction pigments are mentioned in chapters dealing with the individual nutrients. 

Despite the many biochemical and nutritional factors which can influence toxic response, it is reassuring that existing protocols used in safety evaluation, combined with appropriate safety factors, do appear to work in practice. It is much rarer to find adverse reactions in man ascribed to food additives under approved conditions of use than to naturally occurring constituents or contaminants of food. Where adverse reactions have been recognised, they have usually been due to idiosyncratic responses such as allergy to some synthetic food colours, and similar allergies have been found with naturally occurring alternatives, e.g. annatto. ... 

In the early years of their use, plastics were regarded as essentially unreactive materials and there was a widespread ignorance of the chemistry of the materials and of the variety of compounds used in their manufacture. A decade or so ago, reports of adverse reactions arising from the use of plastics in a number of applications began to appear. These included problems of colour modification, flavour and odour taint of packaged food, and also unforeseen biological effects due to the use of plastics in the construction of medical appliances. Health problems associated with vinyl chloride processing led to the... 

Unless great care is taken in control of phenol/acetone ratios, reaction conditions and the use of catalysts, a number of undesirable by-products may be obtained such as the o-,p- and o-,o- isomers of bis-phenol A and certain chroman-type structures. Although tolerable when the bis-phenol A is used in epoxy resins, these have adverse effects on both physical properties and the colour of polycarbonate resins. 

Urticaria due to intake of tartrazine is more widely accepted as an adverse effect and has been demonstrated in a number of studies. During this reaction substances such as histamine are released into the blood which cause the symptoms of red weals on the skin and itching. A number of other food colours and other types of food additives can also cause urticaria and there may be cross-reactivity between colours such as eryth-rosine and sunset yellow. A challenge of patients whose urticaria had improved on a colour-free diet with 0.15 mg of tartrazine, resulted in three out of thirteen developing urticaria within three hours of exposure."... 

Similarly, epoxides are also formed during the reaction of olefins with hydrogen peroxide. Secondary reactions of oxidised polyenoic acids produce red-coloured cyclopentane derivatives (3-137) causing adverse colour changes to stored fish. 

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