Structure V Polymer produced by the ultraviolet irradiation of chlorpromazine under anaerobic conditions

Chlorpromazine behaves differently towards ultraviolet irradiation under anaerobic conditions. A polymerisation process has been proposed10 which involves the liberation of HCl in its initial stages. The polymer (V) was isolated, and upon intracutaneous injection it produced a bluish-purple discoloration typical of that observed in some patients receiving prolonged chlorpromazine medication. It was suggested that the skin irritation that accompanies the discoloration may be a result of the liberation of HCl during photo-decomposition.

The photodegradation of ketoprofen can involve decarboxylation to form an intermediate which then undergoes reduction, or dimerisation of the ketoprofen itself as illustrated in Scheme 4.11.

Stabilisation against photochemical decomposition

Pharmaceutical products can be adequately

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