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Sodium nitroprusside and urapidil, both antihypertensive drugs, have different contraindications and adverse reactions!


Recently, a doctor in the department changed the sodium nitroprusside used for blood pressure reduction to urapidil. Due to the less significant antihypertensive effect of urapidil compared to sodium nitroprusside, it cannot effectively inhibit the increase of blood pressure when using the same dosage. Nurses can only rely on experience to constantly explore and adjust, and need to closely observe changes in blood pressure.

So, some nurses complained, can't they keep using sodium nitroprusside? Why do we have to use urapidil?

So, why would doctors replace sodium nitroprusside with urapidil? With this question in mind, the author carefully read the user manual of sodium nitroprusside, reviewed its relevant information, and gained a deeper understanding of this drug.

1. Adverse reactions of sodium nitroprusside:

Short term use in moderation will not cause adverse reactions. The toxic reaction of this product comes from its metabolites * * * and thiocyanate. * * * is an intermediate metabolite, and thiocyanate is the final metabolite. If * * * cannot be converted to thiocyanate normally, poisoning can occur even if the blood concentration of thiocyanate is normal.

That is to say, short-term use generally does not cause drug accumulation and poisoning. However, as the usage time prolongs, it is necessary to pay attention to its accumulation effect.

Regular monitoring of the patient's liver and kidney function should be carried out during regular treatment. If conditions permit, the concentration of thiocyanates in the blood can be monitored. For applications exceeding 48-72 hours, especially in patients with renal insufficiency, plasma levels of * * * or thiocyanates must be measured daily, with thiocyanates not exceeding 100% μ G/mL, * * * not exceeding 3 μ Mol/mL, if exceeded, medication needs to be discontinued.

During the treatment process, what kind of situation should one be wary of drug poisoning?

When thiocyanate poisoning or overdose occurs, motor disorders, blurred vision, delirium, dizziness, headache, loss of consciousness, nausea, vomiting, tinnitus, and shortness of breath may occur.

***When poisoned or overdosed, symptoms may include disappearance of reflexes, coma, distant heart sounds, hypotension, disappearance of pulse, pink skin, shallow breathing, and dilated pupils.

3. What patients are prone to poisoning?

Patients with renal dysfunction are more prone to thiocyanate poisoning.

Sodium nitroprusside is quickly metabolized in the blood, reaching its maximum effect within 1-2 minutes. After discontinuation, the effect disappears within 2-15 minutes, with a half-life of 2-30 minutes. Thiocyanate is the final metabolite of sodium nitroprusside, and its elimination half-life is 3-7 days when renal function is normal.

Clinical studies abroad have shown that there is a linear relationship between the concentration of plasma thiocyanates and the total amount of intravenous infusion of sodium nitroprusside, as well as renal function levels. People with normal liver and kidney function, unless used for a long time, will not cause the accumulation of * * * and thiocyanates, so poisoning will not occur. However, if a large amount of sodium nitroprusside enters the body in a short period of time, the body will quickly accumulate a large amount of free cyanide, and the relative reduction of thiocyanate synthase in the liver and the absolute decrease of thiocyanate synthase when liver function is damaged will cause obstacles in the process of * * transforming into thiocyanates, leading to * * poisoning.

4. Use with caution and disable:


(1) There is still a lack of human research on the carcinogenicity, teratogenicity, and effects on pregnant and lactating women of this product. Research on its application in children has not been conducted either.

(2) Elderly people should pay attention to the impact of renal dysfunction on the excretion of this product as they age. Elderly people are also sensitive to antihypertensive reactions, so the dosage should be reduced appropriately.

Use with caution in the following situations:

(1) When there is insufficient blood supply to the cerebral or coronary arteries, tolerance to hypotension decreases.

(2) When controlling blood pressure during anesthesia, if there is anemia or low blood volume, it should be corrected before administration.

(3) When brain disease or other intracranial pressure increases, dilating cerebral blood vessels can further increase intracranial pressure.

(4) When liver function is impaired, this product may exacerbate liver damage.

(5) When thyroid function is low, the metabolite thiocyanate of this product can inhibit the uptake and binding of iodine, which may worsen the condition.

(6) When lung function is impaired, this product may exacerbate hypoxemia.

(7) Using this product when lacking vitamin B12 may worsen the condition.

5. Usage:

(1) Intravenous infusion: Dissolve 50mg of this product in 5ml of 5% glucose injection before use, then dilute it in 250ml to 1000ml of 5% glucose injection, and drip intravenously in a dark infusion bottle.

Common dosage for adults: intravenous infusion, starting at 0.5g/kg body weight per minute. According to the treatment response, the dosage is gradually adjusted in increments of 0.5g/kg per minute. The commonly used dosage is 3g/kg per minute of body weight, and the maximum dosage is 10g/kg per minute of body weight.

Common dosage for children: intravenous infusion, 1.4 times body weight per minute? G/kg, gradually adjust the dosage according to the effect.

(2) Micro pumping: Dissolve 50mg of this product in 50ml of 5% glucose injection before use, and start pumping at a rate of 2mg/h. Adjust the pumping amount in a timely manner according to blood pressure.

6. Precautions for use:

(1) This product is sensitive to light and has poor solution stability. The drip solution should be freshly prepared and kept away from light. I have personally witnessed that the sodium nitroprusside in use has fallen off due to the light shielding paper, and the entire liquid inside the 50ml syringe has turned dark green. The newly prepared solution is light brown. If there are any abnormalities, it should be discarded immediately. The storage and application of the solution should not exceed 24 hours. Other drugs should not be added to the solution.

(2) Interference with diagnosis: When using this product, blood carbon dioxide partial pressure, pH value, and bicarbonate concentration may decrease; The plasma concentrations of * * * and thiocyanates may increase due to the metabolism of this product. When the product is exceeded, the arterial lactate concentration may increase, indicating metabolic acidosis.

(3) The medicine has local irritancy, be careful of extravasation.

(4) When using this product for controlled hypotension during anesthesia in young male patients, a large amount, even close to the limit, is required.

(5) If the intravenous drip has reached 10 per minute? G/kg, if the blood pressure is still unsatisfactory after 10 minutes, it should be considered to stop using this product and switch to or add other antihypertensive drugs.

(6) When left heart failure occurs, the use of this product can restore the pumping function of the heart, but when accompanied by hypotension, myocardial positive inotropic drugs such as dopamine or dobutamine should be added at the same time.

(7) During the use of this product, there may occasionally be obvious drug resistance, which should be considered as a precursor to poisoning. At this time, slow down the infusion rate to disappear.

7. Take care of the use of sodium nitroprusside and provide health education.

Due to the fact that sodium nitroprusside takes effect within 1-2 minutes of entering the human body and disappears after stopping infusion for 1-10 minutes, patients often need to maintain medication for a long time. Therefore, during use, it is important to actively introduce the purpose and precautions of sodium nitroprusside to patients and their families, and inform them not to adjust the infusion rate on their own. If using a micro pump, there is no need to change the adjustment button on the micro pump to prevent self adjustment of infusion rate or excessive or frequent changes in body position, which may affect the efficacy or adverse reactions. During use, it is important to closely observe changes in blood pressure and record them in a timely manner. Patients with hypertensive intracerebral hemorrhage should lower their blood pressure slowly and not drop it to normal or below in a short period of time to avoid insufficient cerebral perfusion. When blood pressure is stubborn and does not decrease, one should be alert to the phenomenon of increased intracranial pressure, promptly identify the cause, and replace antihypertensive drugs if necessary.

Adverse reactions:

Occasionally experiencing headaches, dizziness, nausea, fatigue, palpitations, arrhythmia, itching, insomnia, etc. Positional hypotension is less common than prazosin and has no first dose response.


Before using this product in combination with other antihypertensive drugs, there should be a certain interval of time, and the dosage of this product should be adjusted if necessary.

2. A sudden drop in blood pressure may cause bradycardia or even cardiac arrest, and the treatment period generally does not exceed 7 days.

3. Drivers or operators of machinery should use it with caution as it may affect their driving or handling abilities.

4. Excessive intake can cause hypotension, elevate lower limbs and increase blood volume, and if necessary, use vasopressors.

5. Elderly people and those with impaired liver function can enhance the efficacy of this product, and attention should be paid.

From the adverse reactions and side effects of the two drugs, urapidil is significantly safer than sodium nitroprusside, which is why doctors need to replace it in a timely manner.

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