nitroprusside sodium

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 sodium