|
Drug Information
Pharmacokinetics
| Indication
& Dosage | Action
| Interactions |Adverse
Effects & Precautions |
Brands available in Market
Pharmacokinetics.
Sodium nitroprusside is
converted in the erythrocytes to cyanide. Nitric oxide is also released
in vivo. Cyanide is metabolised in the liver to thiocyanate by the
enzyme rhodanase in the presence of thiosulphate and slowly excreted in
the urine. The plasma half-life of thiocyanate is reported to be about 3
days, but may be much longer in patients with renal impairment.
Indication
& Dosage
IV Infusion
HYPERTENSIVE CRISIS: Initially 0.3mcg/kg/min, then adjusted; usual range
0.5-0.6 mcg/kg/min (20-400mcg/min); Max. 8mcg/kg/min (if response, give
for only few hours to avoid cyanide risk); lower doses for patients
already being treated with other antihypertensives and in the felderly.
CONTROLLED HYPOTENSION DURING ANESTHESIA 7 SURGERY: Infusion at lower
doses(max. 1.5mcg/kg/min)
HEART FAILURE: Initially 10-15 mcg/min increased every 5-10 min as
necessary; usual range 10-200mcg/min. Max 280 mcg/min(4mcg/kg/min).
Action
It acts by relaxation of vascular smooth muscle; consequently
it dilates peripheral arteries and veins. It is more active on veins
than on arteries. It reduces both preload & afterload which will
reduce workload on the heart. In hypertensive patients, moderate doses
induce renal vasodilation roughly proportional to the decrease
insystemic appreciable change in RBF and GFR. Hypotensive effect is seen
within a minute or two after the start of an adequate infusion, and it
dissipates almost as rapidly after infusion is discontinued.
Interaction
Diuretics, Inotropic agents:
Useful combination in cardiac failure.
Antihypertensives: Sensitivity enhanced by antihypertensives.
Adverse
Effect & Precautions
Nausea, vomiting, nervousness,
palpitation, sweating, headache, disorientation, methaemoglobinaemia.
Precaution: Sodium nitroprusside decomposes on exposure to light, so the
container must be covered with black paper.
Pregnancy: Use only if clearly indicated.
Breat Feeding: Safety not established.
Man: May be used.
