SODIUM NITROPRUSSIDE
Clinical safety rating
cautionComprehensive clinical and safety monograph for SODIUM NITROPRUSSIDE (SODIUM NITROPRUSSIDE).
Sodium nitroprusside is a prodrug that releases nitric oxide (NO) in vascular smooth muscle cells, activating guanylate cyclase and increasing cGMP, leading to vasodilation of both arterial and venous vessels.
| Metabolism | Sodium nitroprusside undergoes non-enzymatic degradation in erythrocytes and tissues, releasing cyanide. Cyanide is metabolized by rhodanese (thiosulfate sulfurtransferase) to thiocyanate, primarily in the liver and kidneys. |
| Excretion | Renal: approximately 75% as thiocyanate (metabolite) with 25% unchanged; biliary/fecal: minimal (<5%) |
| Half-life | Sodium nitroprusside itself has a half-life of approximately 2 minutes (converted to cyanide in erythrocytes); the metabolite thiocyanate has a terminal half-life of 2.7-7 days (prolonged in renal impairment, requiring monitoring) |
| Protein binding | Sodium nitroprusside: negligible protein binding (<5%); thiocyanate: weakly bound to plasma proteins (approximately 5%) |
| Volume of Distribution | Sodium nitroprusside: approximately 0.2 L/kg (distributes primarily in extracellular fluid); thiocyanate: approximately 0.2-0.3 L/kg (distributes similarly to extracellular water) |
| Bioavailability | Intravenous: 100% (only route of administration); oral: not applicable (no oral bioavailability due to instability and extensive first-pass metabolism) |
| Onset of Action | IV infusion: 30-60 seconds (direct vasodilation); immediate on administration |
| Duration of Action | IV infusion: effects persist only for the duration of infusion, dissipate rapidly (within 1-10 minutes) upon discontinuation due to rapid metabolism; prolonged effects may occur with high doses due to cyanide accumulation |
| Molecular Weight | 297.97 |
Intravenous infusion: Initial 0.3-0.5 mcg/kg/min; titrate up to 10 mcg/kg/min, maximum 10 mcg/kg/min for up to 10 minutes. Usual therapeutic dose: 3 mcg/kg/min. Max cumulative dose: 3.5 mg/kg.
| Dosage form | INJECTABLE |
| Renal impairment | GFR <60 mL/min: Use with caution; reduce initial dose by 50% and monitor for cyanide toxicity. GFR <30 mL/min: Avoid due to risk of thiocyanate accumulation. |
| Liver impairment | Child-Pugh Class B: Reduce initial dose by 50% and monitor for cyanide toxicity; maximum infusion rate 2 mcg/kg/min. Child-Pugh Class C: Contraindicated due to risk of severe cyanide toxicity. |
| Pediatric use | Children: Intravenous infusion 0.3-1 mcg/kg/min initially; titrate to effect, not to exceed 10 mcg/kg/min. Neonates: 0.5-1 mcg/kg/min; maximum 5 mcg/kg/min. |
| Geriatric use | Elderly: Lower initial doses (0.3-0.5 mcg/kg/min) with slower titration; increased sensitivity to hypotension. Monitor for thiocyanate accumulation (normal renal function may decline with age). |
| 1st trimester | Limited human data; use only if clearly needed. Animal studies have shown fetal toxicity at high doses. Risk of cyanide accumulation due to fetal immaturity. |
| 2nd trimester | Use only if benefit outweighs risk. Monitor for maternal hypotension and fetal distress. Risk of cyanide/thiocyanate toxicity. |
| 3rd trimester | May cause fetal bradycardia and acidosis due to maternal hypotension. Avoid prolonged use. Risk of cyanide poisoning in neonate. |
Clinical note
Comprehensive clinical and safety monograph for SODIUM NITROPRUSSIDE (SODIUM NITROPRUSSIDE).
| Placental transfer | Crosses placenta rapidly; fetal levels may approach maternal levels. Cyanide and thiocyanate also cross and can accumulate in fetus. |
| Breastfeeding | Excreted in breast milk in small amounts; thiocyanate accumulation may occur in infant. Avoid if possible; if used, monitor infant for hypotension, weakness, and metabolic acidosis. Use lowest effective dose for shortest duration. |
| Lactation Rating | L4 - Possibly Hazardous |
| Teratogenic Risk | Pregnancy Category C. Risk cannot be ruled out. Animal reproduction studies have not been conducted with sodium nitroprusside. It should only be used in pregnant women if the potential benefit justifies the potential risk to the fetus. Due to its vasodilatory effects and potential for maternal hypotension, fetal hypoxia may occur. Use during labor may cause uterine relaxation and prolonged labor. |
| Fetal Monitoring | Continuous blood pressure monitoring via intra-arterial line is recommended. Monitor heart rate, cardiac output, and systemic vascular resistance. Monitor for signs of cyanide toxicity (metabolic acidosis, altered mental status), especially with prolonged use or in renal impairment. Fetal heart rate monitoring should be considered during labor. |
| Fertility Effects | No human data on fertility effects. Animal studies have not been conducted. No known direct impact on fertility, but severe hypotension or toxicity could potentially affect reproductive function. |
■ FDA Black Box Warning
Sodium nitroprusside can cause excessive hypotension and cyanide toxicity. Continuous monitoring of blood pressure and cyanide/thiocyanate levels is required. Prolonged infusion or high doses increase risk of cyanide poisoning.
| Serious Effects |
Compensatory hypertension (e.g., coarctation of aorta, arteriovenous shunt)Severe hepatic insufficiencySevere renal impairment (e.g., anuria, azotemia)Leber's hereditary optic atrophyTobacco amblyopiaVitamin B12 deficiencyCyanide toxicity or congenital cyanide metabolism disorders
| Precautions | Risk of cyanide toxicity, especially with prolonged infusion or renal impairment, Thiocyanate toxicity with renal failure, Hypotension requiring continuous blood pressure monitoring, Methemoglobinemia (rare) |
| Food/Dietary | No specific food interactions. Patients should avoid excessive vitamin B12 or sulfur-containing supplements due to theoretical risk of increased thiocyanate production. |
| Clinical Pearls | Protect solution from light; wrap infusion set with opaque material. Use only in ICU setting with continuous blood pressure monitoring. Monitor for cyanide toxicity, especially with high doses (>2 mcg/kg/min) or renal impairment. Onset of action is immediate; titrate to effect every 5 minutes. Do not use for more than 48 hours to avoid thiocyanate accumulation. Administer via dedicated IV line; incompatible with many drugs. |
| Patient Advice | This medication is used to rapidly lower blood pressure in emergencies. · You will have continuous blood pressure monitoring; report any headache, dizziness, nausea, or palpitations. · The solution is light-sensitive; the IV bag and tubing are wrapped to protect it. · Inform your doctor if you have kidney or liver disease, or a history of cyanide poisoning. · Do not stop the infusion abruptly; blood pressure must be reduced gradually. |
Loading safety data…