Sodium nitroprusside, photodegradation

A dramatic example of photolysis is the photodegradation of sodium nitroprusside in aqueous solution. Sodium nitroprusside, Na2Fe(CN)5NO-2 H20, is administered by intravenous infusion for the management of acute hypertension. If the solution is protected from light it is stable for at least one year if exposed to normal room light, it has a shelf life of only 4 hours [35]. 

The photodegradation of sodium nitroprusside in aqueous solution remains a classic example of photolytic decomposition [19]. 

Haloperidol A concentrated solution of haloperidol (5 mg/mL) is incompatible with heparin sodium (in sodium chloride or glucose solutions), sodium nitroprusside (in glucose solutions), cefmetazole sodium, diphenhydramine, and sargramostim. Solutions of haloperidol precipitate if diluted with a 0.9% sodium chloride solution.158,159 Photodegradation of haloperidol could be prevented using benzyl alcohol and vanillin.160... 

Asker and Colbert (82) found that Tween 80 enhanced the photodegradation of FD C Blue No. 2 dye. In another report, Asker and Canady (83) reported that Tween 80 had little effect on the photostability of sodium nitroprusside solutions, while polyethylene glycol 300 enhanced it, possibly due to its chelating potential. 

Baird GM, Willoughby ML. Photodegradation of decarbazine. Lancet 1978 2 681. Hartley TF, Philcox JC, Willoughby J. Two methods of monitoring the photodecomposition of sodium nitroprusside in aqueous and glucose solutions. J Pharm Sci 1985 74(6) 668-671. 

Sodium nitroprusside in solution is extremely photosensitive, undergoing rapid and numerous photodegradation reactions (69). The deterioration of the product is evidenced by a color change from brown to blue, resulting from the reduction of the ferric ion to the ferrous ion. Hydrogen cyanide is one of the toxic degradation products formed. Therefore, reconstituted solutions should be stored protected from UV-VIS radiation by wrapping the container with aluminium foil or some other opaque material. Solutions with adequate photoprotection are stable for up to 24 hours (70-72). 

---