nitroprusside

nye-troe-PRUSS-ide

Therapeutic Classification: antihypertensives

Pharmacologic Classification: vasodilators

High Alert

Hypertensive crises.
Controlled hypotension during anesthesia.
Cardiac pump failure or cardiogenic shock (alone or in combination with dopamine).

Produces peripheral vasodilation by a direct action on venous and arteriolar smooth muscle.

Therapeutic effects:

Rapid lowering of BP.
Decreased cardiac preload and afterload.

Absorption: IV administration results in complete bioavailability.

Distribution: Unknown.

Metabolism/Excretion: Rapidly metabolized in RBCs and tissues to cyanide and subsequently by the liver to thiocyanate.

Half-Life: 2 min.

(hypotensive effect)

ROUTE	ONSET	PEAK	DURATION
IV	immediate	rapid	1–10 min

Contraindicated in:

Hypersensitivity;
↓cerebral perfusion.

Use Cautiously in:

Renal impairment (↑ risk of thiocyanate accumulation);
Hepatic impairment (↑ risk of cyanide accumulation);
Hypothyroidism;
Hyponatremia;
Vitamin B deficiency;
OB: Safety not established in pregnancy;
Lactation: Safety not established in breastfeeding;
Geri: Older adults may have sensitivity to drug effects.

CV: dyspnea, hypotension, palpitations

EENT: blurred vision, tinnitus

F and E: acidosis

GI: abdominal pain, nausea, vomiting

Local: phlebitis at IV site

Neuro: dizziness, headache, restlessness

Misc: CYANIDE TOXICITY, thiocyanate toxicity

Drug-drug:

↑hypotensive effect with ganglionic blocking agents, general anesthetics, and other antihypertensives.
Estrogens and sympathomimetics may ↓ the response to nitroprusside.

IV (Adults and Children ): 0.3 mcg/kg/min initially; may be ↑ as needed up to 10 mcg/kg/min (usual dose is 3 mcg/kg/min; not to exceed 10 min of therapy at 10 mcg/kg/min infusion rate).

(Generic available)

Premixed infusion: 20 mg/100 mL 0.9% NaCl; 50 mg/100 mL 0.9% NaCl
Solution for injection: 25 mg/mL

Monitor BP, heart rate, and ECG frequently throughout therapy; continuous monitoring is preferred. Consult physician for parameters. Monitor for rebound hypertension following discontinuation of nitroprusside.
Pulmonary capillary wedge pressure (PCWP) may be monitored in patients with MI or HF.

Lab Test Considerations:

May cause ↓ bicarbonate concentrations, pCO₂, and pH.
- May cause ↑ lactate concentrations.
- May cause ↑ serum cyanide and thiocyanate concentrations.
- Monitor serum methemoglobin concentrations in patients receiving >10 mg/kg and exhibiting signs of impaired oxygen delivery despite adequate cardiac output and arterial pCO₂ (blood is chocolate brown without change on exposure to air). Treatment of methemoglobinemia is 1–2 mg/kg of methylene blue IV administered over several min.

Toxicity and Overdose:

If severe hypotension occurs, drug effects are quickly reversed, within 1–10 min, by decreasing rate or temporarily discontinuing infusion. May place patient in Trendelenburg position to maximize venous return.
- Monitor plasma thiocyanate levels daily in patients receiving prolonged infusions at a rate >3 mcg/kg/min or 1 mcg/kg/min in patients with anuria. Thiocyanate levels should not exceed 1 mmol/L.
- Signs and symptoms of thiocyanate toxicity include tinnitus, toxic psychoses, hyperreflexia, confusion, weakness, seizures, and coma.
- Cyanide toxicity may manifest as lactic acidosis, hypoxemia, tachycardia, altered consciousness, seizures, and characteristic breath odor similar to almonds.
- Acute treatment of cyanide toxicity includes 4–6 mg/kg of sodium nitrite (as a 3% solution) over 2–4 min. This acts as a buffer for cyanide by converting 10% of hemoglobin to methemoglobin. If administration of sodium nitrite is delayed, inhalation of crushed ampule of amyl nitrite for 15–30 sec of every min should be started until sodium nitrite is running. Following completion of sodium nitrite infusion, administer sodium thiosulfate 150–200 mcg/kg (available as 25% and 50% solutions). This will convert cyanide to thiocyanate, which may then be eliminated. If required, entire regimen may be repeated in 2 hr at 50% of the initial doses.

If infusion of 10 mcg/kg/min for 10 min does not produce adequate reduction in BP, manufacturer recommends nitroprusside be discontinued.
- May be administered in left ventricular HF concurrently with an inotropic agent (dopamine, dobutamine) when effective doses of nitroprusside restore pump function and cause excessive hypotension.

IV Administration:

Diluent: Dilute 50 mg of nitroprusside in 250–1000 mL of D5W. Wrap infusion in aluminum foil to protect from light; administration set tubing need not be covered. Amber plastic bags do not offer sufficient protection from light; wrap must be opaque. Freshly prepared solution has a slight brownish tint; discard if solution is dark brown, orange, blue, green, or dark red. Solution must be used within 24 hr of preparation.Concentration: 50–200 mcg/mL.
Rate: Based on patient's weight (see Route/Dosage section). Administer via volumetric infusion pump to ensure accurate dosage rate.

Explain purpose of nitroprusside to patient.
Advise patient to report the onset of tinnitus, dyspnea, dizziness, headache, or blurred vision immediately.
Rep: May cause fetal harm. Prolonged or large doses may cause fetal harm. Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

Decrease in BP without the appearance of side effects.
Treatment of cardiac pump failure or cardiogenic shock by decreasing cardiac preload and afterload.

Nipride RTU, ~~Nitropress~~

Nipride

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Action ⬆ ⬇

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Contraind./Precautions ⬆ ⬇

Adv. Reactions/Side Effects ⬆ ⬇

Interactions ⬆ ⬇

Route/Dosage ⬆ ⬇

Availability ⬆ ⬇

Assessment ⬆ ⬇

Implementation ⬆ ⬇

Patient/Family Teaching ⬆ ⬇

Evaluation/Desired Outcomes ⬆ ⬇

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