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Nitroprusside

Pronunciation

(nye troe PRUS ide)

Index Terms

  • Nitroprusside Sodium
  • Sodium Nitroferricyanide
  • Sodium Nitroprusside

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Solution, Intravenous, as sodium:

Nitropress: 25 mg/mL (2 mL)

Brand Names: U.S.

  • Nitropress

Pharmacologic Category

  • Antihypertensive
  • Vasodilator

Pharmacology

Causes peripheral vasodilation by direct action on venous and arteriolar smooth muscle, thus reducing peripheral resistance; will increase cardiac output by decreasing afterload; reduces aortal and left ventricular impedance

Metabolism

Nitroprusside combines with hemoglobin to produce cyanide and cyanmethemoglobin. Cyanide detoxification occurs via rhodanase-mediated conversion of cyanide to thiocyanate; rhodanase couples cyanide molecules to sulfane sulfur groups from a sulfur donor (eg, thiosulfate, cystine, cysteine). This process has limited capacity and may become overwhelmed with large exposures once sulfur donor supplies are exhausted resulting in toxicity.

Excretion

Urine (as thiocyanate)

Onset of Action

Hypotensive effect: <2 minutes

Duration of Action

Hypotensive effect: 1-10 minutes

Half-Life Elimination

Nitroprusside, circulatory: ~2 minutes; Thiocyanate, elimination: ~3 days (may be doubled or tripled in renal failure)

Use: Labeled Indications

Management of hypertensive crises; acute decompensated heart failure (HF); used for controlled hypotension to reduce bleeding during surgery

Use: Unlabeled

Management of hypertension during acute ischemic stroke

Contraindications

Treatment of compensatory hypertension (aortic coarctation, arteriovenous shunting); to produce controlled hypotension during surgery in patients with known inadequate cerebral circulation or in moribund patients requiring emergency surgery; high output heart failure associated with reduced systemic vascular resistance (eg, septic shock); congenital optic atrophy or tobacco amblyopia

Dosing: Adult

Acute hypertension: Initial: 0.3-0.5 mcg/kg/minute; may be titrated by 0.5 mcg/kg/minute every few minutes to achieve desired hemodynamic effect (Rhoney, 2009); maximum dose: 10 mcg/kg/minute. To avoid toxicity, some recommend a maximum dose of 2 mcg/kg/minute (Marik, 2007).

Acute decompensated heart failure: IV: Initial: 5-10 mcg/minute; may be titrated rapidly (eg, up to every 5 minutes) to achieve desired hemodynamic effect; usual dosage range: 5-300 mcg/minute. Doses >400 mcg/minute are not recommended due to minimal added benefit and increased risk for thiocyanate toxicity (HFSA, 2010).

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Acute hypertension: IV: Initial: 0.3-0.5 mcg/kg/minute; may be titrated every few minutes to achieve desired hemodynamic effect; maximum dose: 10 mcg/kg/minute (Hegenbarth, 2008; NHBPEP, 2005). Doses ≥1.8 mcg/kg/minute are associated with increased cyanide concentration in pediatric patients (Moffett, 2008); monitor cyanide levels with prolonged use (eg, >72 hours) (NHBPEP, 2005).

Dosing: Renal Impairment

No dosage adjustment provided in manufacturer's labeling. However, use in patients with renal impairment may lead to the accumulation of thiocyanate and subsequent toxicity; limit use.

Dosing: Hepatic Impairment

No dosage adjustment provided in manufacturer's labeling; due to the risk of cyanide toxicity, use with caution.

Reconstitution

Prior to administration, nitroprusside sodium should be further diluted by diluting 50 mg in 250-1000 mL of D5W (preferred), LR, or NS.

Use only clear solutions; solutions of nitroprusside exhibit a color described as brownish, brown, brownish-pink, light orange, and straw. Solutions are highly sensitive to light. Exposure to light causes decomposition, resulting in a highly colored solution of orange, dark brown or blue. A blue color indicates almost complete decomposition. Do not use discolored solutions (eg, blue, green, red) or solutions in which particulate matter is visible.

Prepared solutions should be wrapped with aluminum foil or other opaque material to protect from light (do as soon as possible).

Administration

IV infusion only; infusion pump required; must be diluted prior to administration; not for direct injection. Due to potential for excessive hypotension, continuously monitor patient’s blood pressure during therapy.

Compatibility

Stable in D5W (preferred), LR, NS; Note: Exposure to light causes decompensation regardless of the diluent

Y-site administration: Incompatible with drotrecogin alfa, levofloxacin, pantoprazole.

Compatibility in syringe: Incompatible with pantoprazole.

Storage

Store the intact vial at 20°C to 25°C (68°F to 77°F). Protect from light.

Stability of parenteral admixture in D5W, LR, or NS at room temperature (25°C) and at refrigeration temperature (4°C) is 24 hours.

Drug Interactions

Alfuzosin: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Amifostine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When amifostine is used at chemotherapy doses, blood pressure lowering medications should be withheld for 24 hours prior to amifostine administration. If blood pressure lowering therapy cannot be withheld, amifostine should not be administered. Consider therapy modification

Amphetamines: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Antipsychotic Agents (Second Generation [Atypical]): Blood Pressure Lowering Agents may enhance the hypotensive effect of Antipsychotic Agents (Second Generation [Atypical]). Monitor therapy

Barbiturates: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Benperidol: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Blood Pressure Lowering Agents: May enhance the hypotensive effect of Nitroprusside. Monitor therapy

Brimonidine (Topical): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Dapsone (Topical): May enhance the adverse/toxic effect of Methemoglobinemia Associated Agents. Monitor therapy

Diazoxide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

DULoxetine: Blood Pressure Lowering Agents may enhance the hypotensive effect of DULoxetine. Monitor therapy

Herbs (Hypertensive Properties): May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Herbs (Hypotensive Properties): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Levodopa: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa. Monitor therapy

Lormetazepam: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Methylphenidate: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Molsidomine: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Naftopidil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nicergoline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nicorandil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nitric Oxide: May enhance the adverse/toxic effect of Methemoglobinemia Associated Agents. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor patients for signs of methemoglobinemia (e.g., hypoxia, cyanosis) when nitric oxide is used in combination with other agents associated with development of methemoglobinemia. Avoid lidocaine/prilocaine. Monitor therapy

Obinutuzumab: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Management: Consider temporarily withholding blood pressure lowering medications beginning 12 hours prior to obinutuzumab infusion and continuing until 1 hour after the end of the infusion. Consider therapy modification

Pentoxifylline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Phosphodiesterase 5 Inhibitors: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Prilocaine: Methemoglobinemia Associated Agents may enhance the adverse/toxic effect of Prilocaine. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor patients for signs of methemoglobinemia (e.g., hypoxia, cyanosis) when prilocaine is used in combination with other agents associated with development of methemoglobinemia. Avoid lidocaine/prilocaine in infants receiving such agents. Monitor therapy

Prostacyclin Analogues: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Quinagolide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Sodium Nitrite: Methemoglobinemia Associated Agents may enhance the adverse/toxic effect of Sodium Nitrite. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Monitor therapy

Tetracaine (Topical): May enhance the adverse/toxic effect of Methemoglobinemia Associated Agents. Monitor therapy

Yohimbine: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Adverse Reactions

Frequency not defined.

Cardiovascular: Bradycardia, ECG changes, flushing, hypotension (excessive), palpitation, substernal distress, tachycardia

Central nervous system: Apprehension, dizziness, headache, intracranial pressure increased, restlessness

Dermatologic: Rash

Endocrine & metabolic: Metabolic acidosis (secondary to cyanide toxicity), hypothyroidism

Gastrointestinal: Abdominal pain, ileus, nausea, retching, vomiting

Hematologic: Methemoglobinemia, platelet aggregation decreased

Local: Injection site irritation

Neuromuscular & skeletal: Hyperreflexia (secondary to thiocyanate toxicity), muscle twitching

Ocular: Miosis (secondary to thiocyanate toxicity)

Otic: Tinnitus (secondary to thiocyanate toxicity)

Respiratory: Hyperoxemia (secondary to cyanide toxicity)

Miscellaneous: Cyanide toxicity, diaphoresis, thiocyanate toxicity

ALERT: U.S. Boxed Warning

Appropriate administration:

After reconstitution, nitroprusside is not suitable for direct injection. The reconstituted solution must be further diluted in dextrose 5% injection before infusion.

Hypotension:

Nitroprusside can cause precipitous decreases in blood pressure. In patients not properly monitored, these decreases can lead to irreversible ischemic injuries or death. Use only when available equipment and personnel allow blood pressure to be continuously monitored.

Cyanide toxicity:

Except when used briefly or at low (less than 2 mcg/kg/min) infusion rates, nitroprusside injection gives rise to important quantities of cyanide ion, which can reach toxic, potentially lethal levels. The usual dose rate is 0.5 to 10 mcg/kg/min, but infusion at the maximum dose rates should never last more than 10 minutes. If blood pressure has not been adequately controlled after 10 minutes of infusion at the maximum rate, terminate administration immediately. Although acid-base balance and venous oxygen concentration should be monitored and may indicate cyanide toxicity, these laboratory tests provide imperfect guidance.

Warnings/Precautions

Concerns related to adverse effects:

• Cyanide toxicity: [U.S. Boxed Warning]: Except when used briefly or at low (<2 mcg/kg/minute) infusion rates, nitroprusside gives rise to large cyanide quantities. Do not use the maximum dose for more than 10 minutes; if blood pressure is not controlled by the maximum rate (ie, 10 mcg/kg/minute) after 10 minutes, discontinue infusion. Monitor for cyanide toxicity via acid-base balance and venous oxygen concentration; however, clinicians should note that these indicators may not always reliably indicate cyanide toxicity. Patients at risk of cyanide toxicity include those who are malnourished, have hepatic impairment, or those undergoing cardiopulmonary bypass, or therapeutic hypothermia (Rindone, 1992). Discontinue use of nitroprusside if signs and/or symptoms of cyanide toxicity (eg, metabolic acidosis, decreased oxygen saturation, bradycardia, confusion, convulsions) occur. Although not routinely done, sodium thiosulfate has been co-administered with nitroprusside using a 10:1 ratio of sodium thiosulfate to nitroprusside when higher doses of nitroprusside are used (eg, 4-10 mcg/kg/minute) for extended periods of time in order to prevent cyanide toxicity (Shulz, 2010; Varon, 2008); thiocyanate toxicity may still occur with this approach (Rindone, 1992). The use of other agents (eg, clevidipine, labetalol, nicardipine) should be considered if blood pressure is not controlled with nitroprusside.

• Hypotension: [U.S. Boxed Warning]: Excessive hypotension resulting in compromised perfusion of vital organs may occur; continuous blood pressure monitoring by experienced personnel is required.

• Thiocyanate toxicity: Can occur in patients with renal impairment or those on prolonged infusions (ie, >3 mcg/kg/minute for >72 hours).

Disease-related concerns:

• Anemia: When nitroprusside is used for controlled hypotension during surgery, correct pre-existing anemia prior to use when possible.

• Increased intracranial pressure: Use with extreme caution in patients with elevated intracranial pressure.

• Hepatic impairment: Use with extreme caution in patients with hepatic impairment.

• Hypovolemia: When nitroprusside is used for controlled hypotension during surgery, correct pre-existing hypovolemia prior to use when possible.

• Myocardial infarction: Use caution in patients with acute myocardial infarction because of hemodynamic effects and possible coronary steal.

• Renal impairment: Use with extreme caution in patients with renal impairment; use the lowest end of the dosage range; monitor thiocyanate concentrations closely.

Other warnings/precautions:

• Appropriate administration: [U.S. Boxed Warning]: Solution must be further diluted with 5% dextrose in water. Do not administer by direct injection.

Monitoring Parameters

Blood pressure, heart rate (cardiac monitor and blood pressure monitor required); monitor for cyanide and thiocyanate toxicity; monitor venous oxygen saturation; monitor acid-base status as acidosis can be the earliest sign of cyanide toxicity; monitor thiocyanate levels if requiring prolonged infusion (>3 days) or dose >3 mcg/kg/minute or patient has renal dysfunction; monitor cyanide blood levels (if available with appropriate turnaround time) in patients with decreased hepatic function

Consult individual institutional policies and procedures.

Pregnancy Risk Factor

C

Pregnancy Considerations

Animal studies have shown that nitroprusside may cross the placental barrier and result in fetal cyanide levels that are dose-related to maternal nitroprusside levels. However, information related to use in pregnancy is limited.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience flushing, headache, or injection site irritation. Have patient report immediately to prescriber dyspnea, tachycardia, severe dizziness, syncope, illogical thinking, agitation, fasciculations, diaphoresis, muscle rigidity, or considerable nausea (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

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