Adult: For patients not receiving any antihypertensives: Initially, 0.3-1.5 mcg/kg/min. Doses are adjusted gradually according to response. Usual range: 0.5-6 mcg/kg/min. Lower doses should be used in patients receiving antihypertensives. Max rate: 8 mcg/kg/min, discontinue infusion if there is no response after 10 minutes. Child: Lower doses may be required. Neonate: Initially, 0.5 mcg/kg/min, doses may be increased in steps of 0.2 mcg/kg/min. Max: 8-10 mcg/kg/min; 4 mcg/kg/min (if given for longer than 24 hours). Doses are given via IV infusion at a concentration of 50-200 mcg/mL.
Intravenous Induction of hypotension during anaesthesia
Adult: Recommended Max dose: 1.5 mcg/kg/min.
Intravenous Heart failure
Adult: Initially, 10-15 mcg/min, may increase by 10-15 mcg/min every 5-10 minutes according to response. Infusion should be started at 0.3 mcg/kg/min, gradually titrated until the desired effect is achieved or the recommended infusion rate is reached. Usual dose range: 10-200 mcg/min for a Max of 3 days. Max: 280 mcg/min.
Reconstitution
Dilute with 250-1,000 mL of dextrose 5% in water.
Incompatibility
Incompatible with levofloxacin and cisatracurium (simulated Y-site administration).
Contraindications
Compensatory hypertension (e.g. aortic coarctation, arteriovenous shunting); impaired cerebral circulation or in moribund patients (American Society of Anaesthesiologists [ASA] class 5E) coming to emergency surgery; congenital (Leber's) optic atrophy or tobacco amblyopia; acute CHF associated with decreased peripheral vascular resistance. Severe vitamin B12 deficiency.
Special Precautions
Patient with MI, hypertension, pre-existing high intracranial pressure, hypothyroidism, hypothermia. Uncorrected pre-existing anaemia and hypovolemia (correct cases prior to administration). Patient with a predisposition for cyanide toxicity (e.g. malnourished, undergoing cardiopulmonary bypass or therapeutic hypothermia). Patient considered to be poor surgical risks (ASA class 4 and 4E). Do not administer the Max dose for >10 minutes; discontinue infusion if blood pressure is not controlled by the Max rate after 10 minutes. Avoid abrupt withdrawal. Renal and hepatic impairment. Neonates, children, and elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Thiocyanate toxicity, increased intracranial pressure, methaemoglobinaemia. Blood and lymphatic system disorders: Decreased platelet aggregation. Cardiac disorders: Bradycardia, tachycardia. Endocrine disorders: Hypothyroidism. Gastrointestinal disorders: Ileus. Nervous system disorders: Dizziness, restlessness, ataxia, seizures, and stroke. Skin and subcutaneous tissue disorders: Rash. Potentially Fatal: Cyanide toxicity (particularly in patients given sodium nitroprusside at rates much greater than the recommended); excessive hypotension (may lead to compromised perfusion of vital organs).
Monitor thiocyanate concentration if treatment is >3 days; acid-base balance, venous oxygen saturation; blood pressure via arterial line and heart rate. Assess for signs and symptoms of cyanide toxicity (e.g. venous hyperoxaemia with bright red venous blood, metabolic acidosis, confusion, dyspnoea), thiocyanate toxicity (e.g. tinnitus, miosis, hyperreflexia), methaemoglobinaemia (e.g. blue/grey colour of the lips, nails, or skin; dizziness or passing out; severe headache, shortness of breath, abnormal heartbeat), acidosis (e.g. nausea, vomiting, abdominal pain, confusion, fast breathing or shortness of breath, abnormal heartbeat).
Overdosage
Symptoms: Excessive hypotension; cyanide toxicity (e.g. venous hyperoxaemia with bright red venous blood, metabolic acidosis, confusion, dyspnoea, death) or thiocyanate toxicity (e.g. tinnitus, miosis, hyperreflexia). Management: Put the patient into a head-down (Trendelenburg) position to maximise venous return. Cyanide toxicity: Administer sodium nitrite as buffer to convert haemoglobin into methaemoglobin. Give sodium thiosulfate to convert the cyanide into thiocyanate.
Drug Interactions
Enhanced hypotensive effect with other antihypertensives, ganglionic blocking agents, negative inotropic agents, inhaled anaesthetics, volatile liquid anaesthetics.
Action
Description: Mechanism of Action: Sodium nitroprusside is a short-acting hypotensive. It causes relaxation of the vascular smooth muscle and subsequent peripheral vasodilation of the arteries and veins. Vasodilation of the veins stimulates peripheral blood pooling and reduces venous return to the heart, thereby reducing preload. Vasodilation of the arteries decreases vascular resistance, systolic arterial pressure, and afterload. Additionally, dilatation of the coronary arteries also occurs. Onset: Hypotensive effect: <2 minutes. Duration: Hypotensive effect: 1-10 minutes. Pharmacokinetics: Metabolism: Rapidly metabolised to cyanide and cyanmethemoglobin in red blood cells and smooth muscle, leading to release of nitric oxide (active metabolite) in vivo. Undergoes further metabolism in the liver by rhodanase with thiosulfate into thiocyanate. Excretion: Via urine (as thiocyanate). Elimination half-life: Approx 3 days (as thiocyanate).
Chemical Structure
Sodium nitroprusside Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 11953895, Sodium nitroferricyanide(III) dihydrate. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-nitroferricyanide_III_-dihydrate. Accessed Nov. 22, 2023.
Storage
Store between 20-25°C. Protect from light. Diluted solution: Store between 2-8°C for 24 hours. Protect from light.
C02DD01 - nitroprusside ; Belongs to the class of nitroferricyanide derivative agents acting on arteriolar smooth muscle. Used in the treatment of hypertension.
References
Anon. Nitroprusside (Pediatric and Neonatal Lexi-Drugs). Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 10/11/2023.Anon. Nitroprusside. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/09/2023.Anon. Sodium Nitroprusside. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 01/09/2023.Buckingham R (ed). Sodium Nitroprusside. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/09/2023.Joint Formulary Committee. Sodium Nitroprusside. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/09/2023.Nitroprusside. Gold Standard Drug Database in ClinicalKey [online]. Elsevier Inc. https://www.clinicalkey.com. Accessed 01/09/2023.Paediatric Formulary Committee. Sodium Nitroprusside. BNF for Children [online]. London. BMJ Group, Pharmaceutical Press, and RCPCH Publications. https://www.medicinescomplete.com. Accessed 10/11/2023.Pfizer New Zealand Limited. DBL Sodium Nitroprusside 50 mg/2 mL Concentrated Injection Vial data sheet 30 January 2019. Medsafe. http://www.medsafe.govt.nz. Accessed 01/09/2023.Sodium Nitroprusside Injection (Amneal Pharmaceuticals LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 01/09/2023.
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