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.