Nitroprusside

Initially 0.3-0.5 micrograms/kg/min IV, increasing in 0.5 micrograms/kg/min increments to hemodynamic response or headache/nausea. Usual rate 3; rates above 4 are rarely needed. Maximum 10 micrograms/kg/min for no more than 10 minutes. The longer manufacturer discussion starts at 0.3 and titrates every few minutes.

Use an infusion pump, preferably volumetric, not gravity/clamps. Continuously monitor blood pressure, preferably intra-arterially, because rapid onset/offset makes small rate variations consequential. Older adults may be more sensitive. In acute heart failure use invasive hemodynamics plus urine output; stop upward titration when output stops improving, further pressure reduction threatens organ perfusion, or the maximum rate is reached. Do not trade improved output/filling pressure for hypoperfusion.

The source describes diluting 50 mg NITROPRESS in 250-1,000 mL D5W and protecting the container from light with an opaque sleeve/foil; tubing and drip chamber need not be covered. Do not combine other drugs in the solution. Unreacted solution is faint brownish; discard bright blue/green/red discoloration or visible particles. Properly light-protected fresh dilution is described as stable for 24 hours. Do not use flexible containers in series. These are historical preparation statements, not a newly assigned compounding BUD.

Source infusion rates in mL/hour for initial/maximal 0.3/10 micrograms/kg/min respectively. Each row gives weight kg: 200 micrograms/mL pair; 100 micrograms/mL pair; 50 micrograms/mL pair:

10: 1/30; 2/60; 4/120.

20: 2/60; 4/120; 7/240.

30: 3/90; 5/180; 11/360.

40: 4/120; 7/240; 14/480.

50: 5/150; 9/300; 18/600.

60: 5/180; 11/360; 22/720.

70: 6/210; 13/420; 25/840.

80: 7/240; 14/480; 29/960.

90: 8/270; 16/540; 32/1,080.

100: 9/300; 18/600; 36/1,200.

Select a practical concentration; some tabulated rates are impractical. When concentration changes, tubing initially contains the previous concentration. The source's rounded rates are retained, not recalculated.

After more than 500 micrograms/kg delivered faster than 2 micrograms/kg/min, cyanide generation exceeds unaided elimination. Sodium thiosulfate accelerates processing but co-infusion has not been extensively studied and cannot be recommended without reservation. One study found enhanced hypotension; reported thiosulfate infusion rates were 5-10 times the nitroprusside rate. Prolonged/high-dose co-infusion can still produce thiocyanate toxicity and hypovolemia; all nitroprusside precautions remain necessary.

Rare patients above a cumulative 10 mg/kg develop methemoglobinemia. Prolonged rapid infusions, especially with renal impairment, predictably risk thiocyanate toxicity; test when clinical findings suggest either toxicity.

Limit use to brief exposure or avoid. Use the low end of the range, below 2 micrograms/kg/min. Thiocyanate accumulates with renal impairment or prolonged infusion. Monitor cyanide/thiocyanate toxicity. The original warning lists venous hypoxemia, acidosis, mental-status changes and death. Thiocyanate above 60 mg/L is mildly neurotoxic and approximately 200 mg/L can be life-threatening. GlobalRPh suggests considering fenoldopam as an alternative without cyanide/thiocyanate toxicity.

Avoid use.