Wednesday 6 April 2011

NITROPRUSSIDE (SODIUM) NIPRIDE


NITROPRUSSIDE (SODIUM) NIPRIDE
CLASSIFICATION
Rapid acting I.V. antihypertensive agent.
MODE OF ACTION
The hypotensive effect is augmented by ganglion blocking agents, caused by peripheral vasodilatation, as a result of the direct action on the blood vessels, independent of autonomic innervation. It has a marked effect of lowering arterial blood pressure, slight increase in heart rate, and a mild decrease in cardiac output, and a moderate dimunition in calculated peripheral vascular resistance. Action is immediate (0.5 - 1 minute), and usually ends when the I.V. infusion is stopped.
INDICATIONS
Acute hypertensive crisis. Dissecting aortic aneurism. Production of controlled hypotension during anaesthesia in order to reduce bleeding in surgical procedures. Reduction of afterload in cardiogenic shock.
CONTRA INDICATIONS
Hypovolemia. Compensatory hypertension as seen with coarctation of the aorta and AV shunt. Caution should be exercised in using nitroprusside in patients with hypothyroidism and patients with severe renal impairment.
PRECAUTIONS
Adequate facilities, equipment and trained personnel should be available for frequent and vigilant blood pressure monitoring. It should be used with caution and initially in low doses in elderly patients, since they are more sensitive to the drugs hypotensive effects. Patients with liver and renal impairment have an increased risk of suffering toxicity from nitroprusside metabolites (cyanide and thiocyanate). Hypothyroidism. Vitamin B 12 ion insufficiency. Hypothermia. Patients should remain recumbent during the infusion to avoid severe postural hypotensive effects. Light sensitive - infusion must be protected from the light.
ADVERSE REACTIONS
Cyanided poisoning Nausea Retching Emesis Diaphoresis Apprehension Headache Restlessness Agitation Muscle twitching Palpitations Dizziness Weakness Rash Abdominal pain Confusion Anorexia Retrosternal discomfort and chest pain
PROCEDURE
No other dilutions should be used apart form 5 % Dextrose and the solution should be wrapped in aluminium foil to protect from light. Once prepared the solution should not be kept for any longer than 12 hours. See dosage and administration for further information.
PRESENTATION
Sodium Nitroprusside - 50 mg vial powder form.
DOSAGE AND ADMINISTRATION
INFUSION
ADULTS
Add 60 mg Nitroprusside to 5 % Dextrose to total 100 mls. Final concentration 600 mcg/ml. OR 30 mg Nitroprusside to 50 ml 5 % Dextrose. Infusion rate 1 ml/hr = 10 mcg/min. Administer the infusion via an infusion pump, micro drip regulator or any similar device which allows precise measurement of the flow rate. Usual dose range 20 - 200 mcg/min (2 - 20 mls/hr) NB: Solution should have a faint brownish tint - discard solution if it turns blue, green or dark red. NB: Care should be taken to avoid extravasation. Adjustment in the rate of the infusion may be required to keep the blood pressure smoothly controlled and prevent extremes of hypotension and hypertension. The blood pressure usually tends to drop immediately or at least within a few minutes. It is recommended that the blood pressure should not be allowed to drop at a too rapid a rate, and the systolic pressure should not be lowered below 60 mmHg. Too rapid a reduction in blood pressure may result in retching or vomiting, muscular twitching, diaphoresis and agitation. These symptoms subside promptly when the infusion is slowed or temporarily stopped.
PAEDIATRICS
Add 1.5 mg/kg Nitroprusside to 5 % Dextrose to total 50 mls. Final concentration 1 ml/hr = 0.5 mcg/kg/min. Usual dose range 0.5 - 10 mcg/kg/min (1 - 10 ml/hr)
WARNING; Nitroprusside is only to be used as an infusion with sterile 5 % Dextrose.

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