Sodium nitroprusside is available in 2-mL single-dose amber vials as a concentrate for injection with each mL containing the equivalent of 25 mg of sodium nitroprusside dihydrate in sterile water for injection.3282 The concentrate for injection must be further diluted in 250 to 1000 mL of dextrose 5% prior to administration.3282 The diluted solution for infusion should be protected from light using the provided opaque sleeve, aluminum foil, or another opaque material.3282 The manufacturers state that covering the infusion drip chamber and tubing is not necessary.3282
Sodium nitroprusside also is available as a ready-to-use solution in 100-mL single-use (unpreserved) amber vials containing sodium nitroprusside 50 mg in 100 mL of sodium chloride 0.9%.3283 The ready-to-use solution in the amber vial should be stored in the carton until use to protect from light3283 but does not require light protection during administration.3290
pH
The pH of a 1-mg/mL solution in dextrose 5% was reported to be 4.2 (Roche)1579 or 4.74 to 4.94 (Valeant).3284
Sodium Content
Contains sodium 0.335 mEq/50 mg of drug.846
Trade Name(s)
Nipride RTU, Nitropress
Sodium nitroprusside is administered only as an intravenous infusion as the ready-to-use solution3283 or after proper dilution of the concentrate for injection in 250 to 1000 mL of dextrose 5%.3282 The concentrate for injection is not suitable for direct injection.3282 A volumetric infusion pump must be used to administer sodium nitroprusside;3283 the solution for infusion should not be infused through an ordinary intravenous apparatus regulated only by gravity and mechanical clamps.3282
Infusion of sodium nitroprusside should be initiated at a rate of 0.3 mcg/kg/min with an upward titration every few minutes until the desired effect is achieved or the maximum recommended infusion rate of 10 mcg/kg/min has been reached.3282; 3283 Manufacturers state that infusion at the maximum rate of 10 mcg/kg/min should be limited to less than 10 minutes.3282; 3283 The maximum recommended infusion rate for patients with severe renal impairment and anuric patients is less than 3 mcg/kg/min and 1 mcg/kg/min, respectively.3282; 3283
Sodium nitroprusside is colorless to reddish-brown3283 or faint brownish in color.3282 Intact vials should be stored at controlled room temperature and retained in the original carton until use to protect from light.3282; 3283
Sodium nitroprusside protected from light has been reported to be stable for 12 to 24 hours,93; 460; 1296; 1579; 3282 to 48 hours,958 to 13 days,95 or even longer.94; 458; 459; 732
Sodium nitroprusside solutions for infusion should be inspected for particulate matter and discoloration prior to administration; any solution that is discolored or in which particulate matter is visible should not be used.3282; 3283 Sodium nitroprusside may be inactivated and/or rapidly degraded by reactions with trace contaminants, forming highly colored reaction products (usually blue, green, or bright red).3282; 3283 Such solutions should not be used.3282; 3283 It is, therefore, recommended that no other drug be added to sodium nitroprusside solutions.3282; 3283
Dextrose 5% is the recommended infusion solution for admixture of the concentrate for injection90; 91; 3282 although it turns blue more rapidly than the drug in saline solution.732
Sodium nitroprusside 1 mg/mL in 6 solutions in PVC bags was evaluated for production of cyanide, produced by sodium nitroprusside degradation from exposure to 300 foot-candles of light for 72 hours. The solutions tested included 3 nonelectrolyte solutions (dextrose 5%; dextrose 10%; distilled water) and 3 electrolyte solutions (sodium chloride 0.9%; Ringer’s injection, lactated; dextrose 5% in Ringer’s injection, lactated). There was no difference in the amount of cyanide produced among the solutions throughout the first 24 hours. However, the electrolyte solutions exhibited statistically significant lower mean cyanide ion concentrations (about 2 to 5 ppm) than the nonelectrolyte solutions (about 7 to 9 ppm). These levels of cyanide are an order of magnitude greater than in light-protected solutions. It was concluded that electrolyte solutions may be preferable to dextrose 5% for sodium nitroprusside administration and that all doses should be prepared as freshly as possible and protected from light.2023
Temperature Effects
Sodium nitroprusside solutions are heat sensitive. Autoclaving a solution of 100 mg/250 mL in dextrose 5% at 115°C for 30 minutes results in decomposition to a pale blue-green precipitate.458 It has been stated that autoclaving is less deleterious than even moderate exposure to light.94
Light Effects
Solutions of sodium nitroprusside exhibit a color variously described as faint brownish,3282 brown,90 red-brown,3283 brownish-pink,91 light orange,95 and straw.92 These solutions are highly sensitive to light.3282 Exposure to light causes decomposition, resulting in a highly colored solution of light yellow,1579 orange,92 dark brown,91 or blue.90; 91; 92 A blue color indicates almost complete degradation.92
The rate of decomposition of sodium nitroprusside when exposed to light is dependent on such factors as the wavelength and intensity of light, temperature, infusion fluid, pH, and container material. The amount of loss occurring in the administration tubing can be affected additionally by the nature and thickness of the tubing wall, duration of light exposure, volume of fluid, and flow rate.1297
In one study, sodium nitroprusside 0.01% in both water and dextrose 5% in glass bottles exhibited 9 to 10% decomposition in 2 hours and 18 to 20% decomposition in 4 hours on exposure to fluorescent light. No decomposition was detected in either solution in 24 hours when protected from light. In PVC bags, even greater decomposition occurred on exposure to light.460
In another study, 10-mg/mL aqueous solutions of sodium nitroprusside lost 3% in 24 hours on exposure to fluorescent light and 10% in 24 hours when exposed to both fluorescent light and indirect daylight. At a concentration of 200 mg/L in infusion solutions, exposure to bright daylight increased the loss to approximately 15 to 30% in 5 hours. The rate of breakdown was related to the amount of illumination. When the containers were protected from light by wrapping with foil, no decomposition was observed in infusion solutions for 7 days at room temperature and for 2 years at 10 mg/mL in glass tubes at room temperature or 4°C.732
The rate of decomposition of sodium nitroprusside (David Bull Laboratories) 1 mg/mL in dextrose 5% was studied when exposed to fluorescent light and natural daylight. The solutions were stored at 23°C in the burette chambers of an amber light-protective set, a clear colorless set, and a clear set covered with a foil overwrap. With exposure to fluorescent light, losses in the clear burette chamber totaled 11% in 150 minutes and 100% in 24 hours. Both the amber and foil-wrapped clear sets sustained virtually no loss in 4 hours and about a 3 to 4% loss in 24 hours. Natural daylight caused a more rapid drug loss in the unprotected burette; essentially all drug was lost in 30 to 150 minutes, depending on the daylight intensity. The amber set slowed the degradation rate, but 32% was still lost in 2 hours with exposure to intense direct sunlight.1296
Solutions of sodium nitroprusside prepared from the concentrate for injection should be protected from light by wrapping the container with the provided opaque sleeve, aluminum foil, or another opaque material.90; 91; 1297; 3282 The container should be wrapped as soon as practical without delaying therapy.959 Amber plastic bags, which are often used for light protection, have been stated not to provide sufficient protection for sodium nitroprusside against photodegradation. Only opaque materials should be used.733
The effect of the light exposure that sodium nitroprusside infusions receive while flowing through a 3-m long PVC infusion set tubing was evaluated. Sodium nitroprusside infusions in dextrose 5%, sodium chloride 0.9%, and Ringer’s injection, lactated, were studied for 24 and 8 hours at flow rates of 10 and 50 mL/hr, respectively. The delivered amount of sodium nitroprusside was not reduced.958
The stability of sodium nitroprusside (Roche) 100 mcg/mL in dextrose 5% was studied when delivered through tubing exposed to normal room light. No degradation occurred in the infusion container wrapped in foil, but concentration differences in the delivered solution of about 2% were noted at each time point sampled over the 5-hour study. When the effects of different light sources on a 50-mcg/mL solution in dextrose 5% were compared, about a 7% loss occurred on exposure to fluorescent light for 6 hours, but a 32% loss occurred in 1 hour on exposure to direct sunlight.1131
The stability of sodium nitroprusside (Roche) 0.5 and 1.67 mg/mL in dextrose 5% administered by a syringe pump system was evaluated. In polypropylene syringes (Sherwood Medical) exposed to both artificial light and daylight, sodium nitroprusside losses after 24 hours were 26 and 18.7% at 0.5 and 1.67 mg/mL, respectively. The level of free cyanide exceeded 2 mcg/mL. The time to 10% decomposition was about 4 hours. Syringes wrapped in foil exhibited less than a 5% loss in 24 hours. A comparison of the decomposition occurring in the delivery tubing showed that about 10.3 and 3.7% were lost from the 0.5- and 1.67-mg/mL concentrations, respectively, when delivered by pumps at 3 mL/hr through tubing exposed to the light. Wrapping the line with foil prevented any decomposition over the 24-hour study.1130
Sodium nitroprusside (Roche) 50 mg/50 mL in dextrose 5% exhibited no change in appearance and no loss when stored for 24 hours at 25°C in 60-mL plastic syringes (Becton Dickinson) wrapped in foil;1579 however, if the syringes were not wrapped in foil for light protection, the solution turned yellow in 12 hours and had approximately 11, 17, and 22% losses in 6, 12, and 24 hours, respectively.1579
Syringes
Sodium nitroprusside (Valeant) 1 mg/mL in dextrose 5% packaged as 6.25 mL in 20-mL polypropylene syringes (Becton Dickinson) and wrapped in aluminum foil was physically and chemically stable for 9 days when stored at 4°C.3284
Sorption
Sodium nitroprusside was shown not to exhibit sorption to PVC bags and tubing, polyethylene tubing, Silastic tubing, and polypropylene syringes.536; 606; 1131
Standardize 4 Safety
One or more standardized concentrations for this drug have been established through Standardize 4 Safety (S4S), a national patient safety initiative to reduce medication errors, especially during transitions of care. (See Standardize 4 Safety in Users Guide.) Recommendations developed to date through this initiative are available at www.ashp.org/pharmacy-practice/standardize-4-safety-initiative.
Table 1: Standardize 4 Safety Continuous IV Infusion Standard Concentrations for Sodium Nitroprusside3635; 3636
| Patient Population | Concentration Standards | Dosing Units |
|---|---|---|
| Adults | 200 mcg/mL 500 mcg/mL | mcg/kg/minute |
| Pediatric patients (50 kg) | 200 mcg/mL 500 mcg/mL | mcg/kg/minute |
For a list of references cited in the text of this monograph, search the monograph titled References.