Nitropress Dosage

Generic name: sodium nitroprusside
Dosage form: injection

This dosage information does not include all the information needed to use Nitropress safely and effectively. See full prescribing information for Nitropress.

The information at Drugs.com is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Dilution to proper strength for infusion: Depending on the desired concentration, the solution containing 50 mg of NITROPRESS must be further diluted in 250-1000 mL of sterile 5% dextrose injection. The diluted solution should be protected from light, using the supplied opaque sleeve, aluminum foil, or other opaque material. It is not necessary to cover the infusion drip chamber or the tubing.

Verification of the chemical integrity of the product: Sodium nitroprusside solution can be inactivated by reactions with trace contaminants. The products of these reactions are often blue, green, or red, much brighter than the faint brownish color of unreacted NITROPRESS. Discolored solutions, or solutions in which particulate matter is visible, should not be used. If properly protected from light, the freshly diluted solution is stable for 24 hours.

No other drugs should be administered in the same solution with sodium nitroprusside.

Avoidance of excessive hypotension: While the average effective rate in adults and children is about 3 mcg/kg/min, some patients will become dangerously hypotensive when they receive NITROPRESS at this rate. Infusion of sodium nitroprusside should therefore be started at a very low rate (0.3 mcg/kg/min), with upward titration every few minutes until the desired effect is achieved or the maximum recommended infusion rate (10 mcg/kg/min) has been reached.

Because sodium nitroprusside’s hypotensive effect is very rapid in onset and in dissipation, small variations in infusion rate can lead to wide, undesirable variations in blood pressure. Sodium nitroprusside should not be infused through ordinary I.V. apparatus, regulated only by gravity and mechanical clamps. Only an infusion pump, preferably a volumetric pump, should be used.

Because sodium nitroprusside can induce essentially unlimited blood-pressure reduction, the blood pressure of a patient receiving this drug must be continuously monitored, using either a continually reinflated sphygmomanometer or (preferably) an intra-arterial pressure sensor. Special caution should be used in elderly patients, since they may be more sensitive to the hypotensive effects of the drug.

When sodium nitroprusside is used in the treatment of acute congestive heart failure, titration of the infusion rate must be guided by the results of invasive hemodynamic monitoring with simultaneous monitoring of urine output. Sodium nitroprusside can be titrated by increasing the infusion rate until:

  • measured cardiac output is no longer increasing,

  • systemic blood pressure cannot be further reduced without compromising the perfusion of vital organs, or

  • the maximum recommended infusion rate has been reached, whichever comes earliest. Specific hemodynamic goals must be tailored to the clinical situation, but improvements in cardiac output and left ventricular filling pressure must not be purchased at the price of undue hypotension and consequent hypoperfusion.

The table below shows the infusion rates corresponding to the recommended initial and maximal doses (0.3 mcg/kg/min and 10 mcg/kg/min, respectively) for both adults and children of various weights. Some of the listed infusion rates are so slow or so rapid as to be impractical, and these practicalities must be considered when the concentration to be used is selected. Note that when the concentration used in a given patient is changed, the tubing is still filled with a solution at the previous concentration.

Avoidance of cyanide toxicity: As described in CLINICAL PHARMACOLOGY above, when more than 500 mcg/kg of sodium nitroprusside is administered faster than 2 mcg/kg/min, cyanide is generated faster than the unaided patient can eliminate it. Administration of sodium thiosulfate has been shown to increase the rate of cyanide processing, reducing the hazard of cyanide toxicity. Although toxic reactions to sodium thiosulfate have not been reported, the co-infusion regimen has not been extensively studied, and it cannot be recommended without reservation. In one study, sodium thiosulfate appeared to potentiate the hypotensive effects of sodium nitroprusside.

Co-infusions of sodium thiosulfate have been administered at rates of 5-10 times that of sodium nitroprusside. Care must be taken to avoid the indiscriminate use of prolonged or high doses of sodium nitroprusside with sodium thiosulfate as this may result in thiocyanate toxicity and hypovolemia. Incautious administration of sodium nitroprusside must still be avoided, and all of the precautions concerning sodium nitroprusside administration must still be observed.

Infusion Rates (mL/hour) to Achieve Initial (0.3 mcg/kg/min) and

Maximal (10 mcg/kg/min) Dosing of NITROPRESS

Volume

250 mL

500 mL

1000 mL

NITROPRESS

50 mg

50 mg

50 mg

concentration

200 mcg/mL

100 mcg/mL

50 mcg/mL

pt

weight

kg

lbs

init

max

init

max

init

max

10

22

1

30

2

60

4

120

20

44

2

60

4

120

7

240

30

66

3

90

5

180

11

360

40

88

4

120

7

240

14

480

50

110

5

150

9

300

18

600

60

132

5

180

11

360

22

720

70

154

6

210

13

420

25

840

80

176

7

240

14

480

29

960

90

198

8

270

16

540


32

1080

100

220

9

300

18

600

36

1200

Consideration of methemoglobinemia and thiocyanate toxicity: Rare patients receiving more than 10 mg/kg of sodium nitroprusside will develop methemoglobinemia; other patients, especially those with impaired renal function, will predictably develop thiocyanate toxicity after prolonged, rapid infusions. In accordance with the descriptions in ADVERSE REACTIONS above, patients with suggestive findings should be tested for these toxicities.

WARNING: Do not use flexible container in series connections.

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