Nitroprusside

Uses

Sodium nitroprusside is used for the immediate reduction of blood pressure of adult and pediatric patients in hypertensive crises. Concomitant longer-acting antihypertensive medication should be administered so that the duration of treatment with sodium nitroprusside can be minimized. Sodium nitroprusside is also used for producing controlled hypotension in order to reduce bleeding during surgery. This is also used for the treatment of acute congestive heart failure.

Dosage

Nitroprusside dosage

Intravenous Hypertensive crisis:

• Adult: For patients not receiving any antihypertensives, initially 0.3-1.5 mcg/kg/ min, adjust 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 min. May continue for a few hr if there is response. Introduce oral antihypertensive as soon as possible.
• Child: Initially, 250-500 nanograms/kg/min, rate may be repeatedly doubled at intervals of 15-20 min until the desired effect is achieved or treatment is judged ineffective. Max rate: 6 mcg/kg/min.
• Elderly: Lower doses may be required.

Induction of hypotension during anaesthesia :

• Adult: Recommended max dose: 1.5 mcg/kg/min.

Heart failure:

• Adult: Intially 10-15 mcg/min, may increase by 10-15 mcg/min every 5-10 min according to response; usual range 10-200 mcg/min. Max: 280 mcg/min.

Side Effects

Bradyarrhythmia, hypotension, palpitations, tachyarrhythmia Apprehension, restlessness, confusion, dizziness, headache, somnolence Rash, sweating, Thyroid suppression, Injection site irritation, Muscle twitch, oliguria, renal azotemia, Cardiac dysrhythmia, hemorrhage, decreased platelet aggregation, excessive hypotensive response, Raised intracranial pressure, Metabolic acidosis, Bowel obstruction, Methemoglobinemia, Cyanide poisoning, Thiocyanate toxicity

Precaution

Hypothyroidism, renal and hepatic impairment, ischaemic heart disease, impaired cerebral circulation, elderly. Monitor blood thiocyanate concentration if treatment is longer than 3 days and should not exceed 100 mcg/ml. Monitor acid-base balance, venous oxygen concentration and BP. Caution to avoid extravasation. To be diluted with sterile dextrose 5% solution before infusion. Avoid sudden withdrawal. Leber's optic atrophy, low plasma-cobalamin concentrations, impaired pulmonary function. Pregnancy and lactation.

Interaction

Additive effect when used with other antihypertensives. May prolong the fibrinolytic activity of alteplase. Risk of severe hypotension if used with phosphodiesterase inhibitors. May reduce serum digoxin levels.

Pregnancy & Breastfeeding use

Pregnancy Category C. There are no adequate, well-controlled studies of Sodium Nitroprusside in either laboratory animals or pregnant women. It is not known whether Sodium Nitroprusside can cause fetal harm when administered to a pregnant woman or can affect reproductive capacity. Sodium Nitroprusside should be given to a pregnant woman only if clearly needed.

Nursing Mothers: It is not known whether sodium nitroprusside and its metabolites are excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from sodium nitroprusside, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Contraindication

Sodium stibogluconate is exceedingly toxic to veins. One of the practical problems is that after a few doses it can become exceedingly difficult to find a vein in which to inject the drug. The insertion of a PICC does not prevent the problem and can instead exacerbate it: the entire vein along the course of the PICC line can become inflamed and thrombose. Large doses of sodium stibogluconate are often administered as dilute solutions.

Pancreatitis is a common deleterious effect of the drug, and the serum amylase or lipase should be monitored twice weekly; there is no need to stop treatment if the amylase remains less than four times the upper limit of normal; if the amylase rises above the cut-off, then treatment should be interrupted until the amylase falls to less than twice the upper limit of normal, whereupon treatment can be resumed. Cardiac conduction disturbances are less common, but ECG monitoring while the medicine is injected is advisable and changes quickly reverse after the drug is stopped or the infusion rate is decreased.

The drug can be given intramuscularly but is exceedingly painful when given by this route. It can also be given intralesionally when treating cutaneous leishmaniasis (i.e., injected directly into the area of infected skin) and again, this is exceedingly painful and does not give results superior to intravenous administration.

Sodium stibogluconate can also cause a reduced appetite, metallic taste in mouth, nausea, vomiting, diarrhoea, headache, tiredness, joint pains, muscle aches, dizziness, and anaphylaxis.

Special Warning

Renal impairment: Dosage adjustments may be necessary

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