Drug Interaction:
Agents for Hypertensive Emergencies- Nitoprusside Sodium, Fenoldopam mesylate, Diazoxide Parentral
None reported
Indication:
Hypertensive crisis
Agents for Hypertensive Emergencies- Nitoprusside Sodium, Fenoldopam mesylate, Diazoxide Parentral
Adverse Reaction:
Rapid blood pressure reduction-
Abdominal pain, apprehension, diaphoresis, dizziness, headache, mucle twitching, nausea,
palpitations, restlessness,retching and retosternal discomfort have been noted when blood
pressure was reduced too rapidly.
Symptoms quickly disappeared when the infusion was slowed or discontinued, and they
did not reappaer with a continued ( or resumed ) slower infusion.
Cardiovascular- Bradycardia, ECG, changes, tachycardia
Hemotologic - Decreased platellet aggregation, methemoglobinemia
Body as a whole- Thiocyanate toxicity, flushing, venous streaking, irritation at the infusion site, rash,hypothyroidism, ileus, increased intracranial pressure
Contra-Indications:
Treatment of compensatory hypertension, where the primary hemodynamic lesion is aortic coarctation or artriovenous shunting, to produce hypotension during surgery in patients with known inadequate cerbral circulation or moribund patients coming to emergency surgery
Special precautions:
Excessive hypotension- Small transcient excesses in the infusion rate of nitroprusside can result in excessive hypotension, sometimes to levels so low as to compromise the perfusion of vital organs.
These hemodynamic changes may lead to variety of associated symptoms
Cyanide toxicity- Nitropruside infusions at rates > 2mcg/kg/min generate CN- faster than the body can normally dispose of it. (When sodium thiosulfate is given, the bodys capacity for CN- elimination is greatly increased.)
Hypertensive patients and patients concomittantly receiving other antihypertensive medications may be more sensitive to theeffects of notroprusside.
Methemoglobineamia- Nitroprusside infusions can cause seqestration of hemoglobin as
methemoglobin. The back conversion process is normally rapid and clinically significant
methemoglobenemia ( 10% ) is seen only rarely
Hepatic function impairment- since cyanide is metabolised by hepatic enzymes, it may accumulate in patients with severe liver impairment. Therefore, use with caution in patients with hepatic insufficiency
Elderly- Use special caution as elderly patients may become more sensitive to the hypotensive effects of the drug
Pregnancy: Give to a pregnant woman only if clearly needed
Lactation: Because of the potential for serious adverse reactions in nursing infants, decide whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the
mother.
Dosages/ Overdosage Etc:
Indications:
Hypertensive criises
Dosage:
Dissolve the contents of a 50mg vial in 2 to 3 ml dextrose in water or sterile water for injection. Depending on the desired concentration, the intially reconstituted solution containing 50 mg must be further diluted in 250 to 1000 ml 5% dextrose injection.
Overdosage-
Symptoms Toxivity has occured at doses well below the recommended maximum infusion rate of 10mcg/kg/min. Overdosage of nityroprusside can be manifested as excessive hypotension, cyanide toxicity, or as thiocyanate toxicity
Treatment
1. Measure cyanide levels and blood gases for venous hyperoxemia or acidosis
2. Acidosis may not disappear until > 1 hour after the appearance of dangerous cyanide levels. Do not wait for laboratory tests.
3. Reasonable suspicion of cyanide toxicity is adequate grounds for initiation of treatment
4. Treatment of cyanide toxicity consists of - Discontinuing the administration of nitroprusside, providing a buffer for cyanide by using sodium nitrate to convert as much HgB into methemoglobin as te patient can safely tolerate, and then infusing sodium thiosulfate insufficient quantity to convert cyanide into thiocyanate
5. Medications for treratment are contained in commercially available cyanide antidote kits.
6. Hemodialysis is ineffective in removal of cyanide, but it will eliminate most thiocyanide
Missed dose-
1. If you miss a dose of this medicine, take it as soon as possible.
2. However, if it is almost time for next dose, skip the missed dose and go back to your regular dosing schedule.
3. Do not double doses.
Pharmacology/ Pharmacokinetics:
Agents for Hypertensive Emergencies- Nitoprusside Sodium, Fenoldopam mesylate, Diazoxide Parentral
Pharmacology:
Nitroprusside is a potent IV antihypertensive agent. The principal pharmacological reaction of nitroprusside is relaxation of vascular smooth muscle and consequent dilation of peripheral ateries and veins.Other smooth muscle (eg. uterus, duodenum ) is not affected. Nitroprusside is more active on veins than on arteries, but this selectivity is much less marked than nitroglycerine.
Dilation of the veins promotes peripheral pooling of blood and decreases venous return to the heart, thereby reducing left ventricular end-diastolic pressure and pulmonary capillary wedge pressure (preload). Arteiolar relaxation reduces systemic vascular resistence, systolic arterial pressure and mean arterial pressure and mean arterial pressure (aftetload). Dilation of the arteries also occurs.
Pharmacokinetics:
Infused nitroprusside is rapidly distributed to a volume that is approximately coextensive with extracellular space. The drug is cleared from volume by intererythrocytic reaction with haemoglobin (HgB) and nitroprusside resulting circulatory half-life is about 2 minutes
Interaction with Food:
Not reported
Pregnancy and lactation:
Pregnancy:
Give to a pregnant woman only if clearly needed
Lactation:
Because of the potential for serious adverse reactions in nursing infants, decide whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Manufacturer Details