Nitropress


nitroprusside sodium

Nipride, Nitropress

Pharmacologic class: Vasodilator

Therapeutic class: Antihypertensive

Pregnancy risk category C

FDA Box Warning

After reconstitution with appropriate diluent, drug isn't suitable for direct injection. Dilute reconstituted solution further in sterile 5% dextrose injection before infusing.

Drug may cause steep blood pressure decrease. In patients not properly monitored, this decrease can lead to irreversible ischemic injury or death. Give drug only when available equipment and personnel allow continuous blood pressure monitoring.

Except when used briefly or at low infusion rates, drug gives rise to significant amount of cyanide ion, which can reach toxic, potentially lethal levels. Infusion at maximum dosage rate should never last more than 10 minutes. If blood pressure isn't adequately controlled after 10 minutes of maximum-rate infusion, end infusion immediately. Monitor acid-base balance and venous oxygen concentration, but be aware that, although these tests may indicate cyanide toxicity, they provide imperfect guidance.

• Review these warnings thoroughly before giving drug.

Action

Interferes with calcium influx and intracellular activation of calcium, causing peripheral vasodilation and direct blood pressure decrease

Availability

Injection: 50 mg/vial in 2 ml- and 5-ml vials

Indications and dosages

➣ Hypertensive emergencies; controlled hypotension during anesthesia

Adults and children: 0.3 to 10 mcg/kg/minute I.V., titrated to response

Dosage adjustment

• Hepatic insufficiency

• Renal impairment

• Elderly patients

Contraindications

• Hypertension caused by aortic coarctation or atrioventricular shunting

• Acute heart failure caused by reduced peripheral vascular resistance

• Congenital (Leber's) optic atrophy, tobacco amblyopia

• Inadequate cerebral circulation

• Moribund patients

Precautions

Use cautiously in:

• hepatic or renal disease, fluid and electrolyte imbalances, hypothyroidism

• elderly patients

• pregnant or breastfeeding patients

• children.

Administration

Be aware that nitroprusside is a high-alert drug.

Give only in settings with trained personnel and continuous blood pressure monitoring equipment.

• Dilute 50 mg in 2 to 3 ml of dextrose 5% in water (D5W); then dilute in 250 to 1,000 ml of D5W.

• Administer with microdrip regulator, infusion pump, or other device that allows precise flow rate measurement.

• Wrap infusion solution in aluminum foil or other opaque material to protect it from light.

Adverse reactions

CNS: increased intracranial pressure

CV: ECG changes, bradycardia, tachycardia, marked hypotension

GI: ileus

Hematologic: decreased platelet aggregation, methemoglobinemia

Metabolic: hypothyroidism

Skin: rash, flushing

Other: pain, irritation, and venous streaking at injection site; too-rapid blood pressure decrease (causing apprehension, restlessness, palpitations, retrosternal discomfort, nausea, retching, abdominal pain, diaphoresis, headache, dizziness, muscle twitching); thiocynate or cyanide toxicity (initially, tinnitus, miosis, and hyper-reflexia) at blood level of 60 mg/L; severe cyanide toxicity (air hunger, confusion, lactic acidosis, death) at level of 200 mg/L

Interactions

Drug-drug. Enflurane, ganglionic blockers, halothane, negative inotropic drugs, volatile liquid anesthetics: severe hypotension

Drug-diagnostic tests. Creatinine: increased level

Methemoglobin: hemoglobin sequestration as methemoglobin

Patient monitoring

Measure blood pressure frequently (preferably with continuous arterial line) to detect rapid drop.

• Monitor injection site closely to avoid extravasation. Use central line whenever possible. Ensure that infusion rate is precisely controlled to prevent too-rapid infusion.

• Obtain baseline ECG and monitor for changes.

Watch for signs and symptoms of cyanide toxicity (lactic acidosis, dyspnea, headache, vomiting, confusion, and loss of consciousness).

Patient teaching

• Tell patient he'll be closely monitored during therapy.

Instruct patient to immediately report headache, nausea, or pain at injection site.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.

nitroprusside

(nye-troe-pruss-ide) nitroprusside,

Nitropress

(trade name)

Classification

Therapeutic: antihypertensives
Pharmacologic: vasodilators
Pregnancy Category: C

Indications

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

Action

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

Therapeutic effects

Rapid lowering of BP.Decreased cardiac preload and afterload.

Pharmacokinetics

Absorption: IV administration results in complete bioavailability.Distribution: Unknown.Metabolism and Excretion: Rapidly metabolized in RBCs and tissues to cyanide and subsequently by the liver to thiocyanate.Half-life: 2 min.

Time/action profile (hypotensive effect)

ROUTEONSETPEAKDURATION
IVimmediaterapid1–10 min

Contraindications/Precautions

Contraindicated in: Hypersensitivity;↓ cerebral perfusion.Use Cautiously in: Renal disease (↑ risk of thiocyanate accumulation);Hepatic disease (↑ risk of cyanide accumulation);Hypothyroidism;Hyponatremia;Vitamin B deficiency; Obstetric / Lactation: Safety not established; Geriatric: May have ↑ sensitivity to drug effects.

Adverse Reactions/Side Effects

Central nervous system

  • dizziness (most frequent)
  • headache (most frequent)
  • restlessness

Ear, Eye, Nose, Throat

  • blurred vision
  • tinnitus

Cardiovascular

  • dyspnea
  • hypotension
  • palpitations

Gastrointestinal

  • abdominal pain (most frequent)
  • nausea (most frequent)
  • vomiting

Fluid and Electrolyte

  • acidosis

Local

  • phlebitis at IV site

Miscellaneous

  • cyanide toxicity (life-threatening)
  • thiocyanate toxicity

Interactions

Drug-Drug interaction

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

Route/Dosage

Intravenous (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).

Availability (generic available)

Injection: 25 mg/mL

Nursing implications

Nursing assessment

  • 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 p H.
    • 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 minutes.
    • 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 millimole/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 (vaporole, aspirole) of amyl nitrite for 15–30 sec of every minute 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.

Potential Nursing Diagnoses

Ineffective tissue perfusion (Indications)

Implementation

  • 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.
  • Intravenous Administration
  • pH: 3.0–6.0.
  • Continuous Infusion: 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 infusion pump to ensure accurate dosage rate.
  • Y-Site Compatibility: amikacin, aminophylline, argatroban, atropine, aztreonam, bivalirudin, bumetanide, calcium chloride, calcium gluconate, cefazolin, cefotaxime, cefoxitin, ceftriaxone, cefuroxime, chloramphenicol, cimetidine, clindamycin, cyclosporine, daptomycin, dexamethasone sodium phosphate, digoxin, diltiazem, dopamine, doxycycline, enalaprilat, epinephrine, ertapenem, esmolol, famotidine, fenoldopam, fentanyl, fluconazole, furosemide, ganciclovir, gentamicin, granisetron, heparin, hydrocortisone sodium succinate, hydromorphone, insulin, isoproterenol, ketorolac, labetalol, lidocaine, linezolid, lorazepam, magnesium sulfate, meperidine, methylprednisolone sodium succinate, metoclopramide, metoprolol, metronidazole, micafungin, midazolam, milrinone, morphine, nafcillin, nesiritide, nicardipine, nitroglycerin, norepinephrine, ondansetron, palonosetron, pancuronium, pantoprazole, penicillin G potassium, phenylephrine, phytonadione, piperacillin/tazobactam, potassium chloride, potassium phosphate, procainamide, propofol, propranolol, protamine, ranitidine, sodium bicarbonate, tacrolimus, ticarcillin/clavulanate, tirofiban, tobramycin, vancomycin, vasopressin, verapamil
  • Y-Site Incompatibility: acyclovir, ampicillin, caspofungin, ceftazidime, diazepam, diphenhydramine, erythromycin, hydralazine, hydroxyzine, levofloxacin, phenytoin, prochlorperazine, promethazine, quinupristin/dalfopristin, trimethoprim/sulfamethoxazole, voriconazole

Patient/Family Teaching

  • Advise patient to report the onset of tinnitus, dyspnea, dizziness, headache, or blurred vision immediately.

Evaluation/Desired Outcomes

  • Decrease in BP without the appearance of side effects.
  • Treatment of cardiac pump failure or cardiogenic shock.

Nitropress®

Nitroprusside sodium, see there.