Nitrocef

Indications

Sodium Nitroprusside is a hospital medicine used for the rapid lowering of blood pressure in a hypertensive emergency (dangerously high blood pressure that is damaging organs). It is also used to control blood pressure during some operations to reduce bleeding, and to treat sudden severe heart failure in intensive care.

How It Works

Inside the body, nitroprusside releases nitric oxide, a natural chemical that relaxes the muscle in the walls of both arteries and veins. This widens the blood vessels, lowers blood pressure within minutes and reduces the workload on the heart. The effect stops within a few minutes after the infusion is stopped, which allows very close control.

Dosage and Administration

It is given only by a doctor or nurse in hospital, usually in an intensive care unit, as a continuous drip into a vein (intravenous infusion) using an infusion pump. The concentrate is always diluted before use, and the solution and tubing are protected from light. The dose is started low and adjusted every few minutes according to continuous blood pressure monitoring, as prescribed. Treatment is kept as short as possible.

Interactions

• Other blood pressure lowering medicines, anaesthetics and Sildenafil or Tadalafil can add to the fall in blood pressure; use with PDE-5 inhibitors is avoided.
• Medicines such as Riociguat should not be combined with it.
• The care team will review all medicines given at the same time.

Contraindications

• High blood pressure that compensates for another problem, such as narrowing of the aorta (coarctation) or a shunt between blood vessels.
• Inherited Leber's optic atrophy or tobacco amblyopia (eye nerve conditions linked to cyanide handling).
• Known vitamin B12 deficiency or poor ability to handle cyanide.
• Severe heart failure with low vascular resistance, and some surgery patients with poor blood flow to the brain.

Side Effects

The most common effect is a drop in blood pressure that is too fast or too large, causing dizziness, nausea, vomiting, sweating, restlessness, headache, palpitations and abdominal pain. Longer use or high doses can lead to build-up of cyanide and thiocyanate, which can cause confusion, muscle spasms, acidosis and, rarely, severe poisoning. Low thyroid function and a drop in blood oxygen may also occur.

The care team must be alerted at once to any chest pain, confusion, severe drowsiness, breathing difficulty, seizures or very low blood pressure during the infusion.

Pregnancy and Lactation

It may be used in pregnancy only in an emergency when the benefit is judged to outweigh the risk, as cyanide can reach the baby. It is not known whether it passes into breast milk; breastfeeding is usually stopped during treatment.

Precautions and Warnings

• Blood pressure must be monitored continuously.
• Blood tests for acid levels, and for cyanide or thiocyanate with longer use or kidney problems, may be needed.
• Use with caution in kidney or liver disease, low thyroid function, and in older people.
• The solution must be protected from light; a strongly coloured (blue, green or dark red) solution must not be used.

Overdose

Overdose causes a severe drop in blood pressure and signs of cyanide poisoning (confusion, acidosis, breathing problems, collapse). The infusion is stopped and specific antidotes such as Sodium Thiosulfate and Hydroxocobalamin may be given by the hospital team.

Therapeutic Class

Direct-acting vasodilator; antihypertensive for emergency use.

Storage

Hospital use: store below 25°C, protected from light, as directed on the pack. Diluted solution must be protected from light and used within the time stated on the pack.