Sodium nitroprusside adverse effects

Nitroprusside [nye troe PRUSS ide] is administered intravenously, and causes prompt vasodilation, with reflex tachycardia. It is capable of reducing blood pressure in all patients, regardless of the cause of hypertension. The drug has little effect outside the vascular system, acting equally on arterial and venous smooth muscle. [Note Because nitroprusside also acts on the veins, it can reduce cardiac preload.] Nitroprusside is metabolized rapidly (t1/2 of minutes) and requires continuous infusion to maintain its hypotensive action. Sodium nitroprusside exerts few adverse effects except for those of hypotension caused by overdose. Nitroprusside metabolism results in cyanide ion production, although cyanide toxicity is rare and can be effectively treated with an infusion of sodium thiosulfate to produce thiocyanate, which is less toxic and is eliminated by the kidneys (Figure 19.14). [Note Nitroprusside is poisonous if given orally because of its hydrolysis to cyanide.]... 

Discuss the limiting factors (with regard to adverse effects) to administration of sodium nitroprusside. 

The most clinically important adverse effects of sodium nitroprusside are profound hypotension and the accumulation of cyanide and thiocyanate. Thiocyanate may accumulate in the blood of patients receiving sodium nitroprusside therapy, especially in those with impaired renal function. Thiocyanate is mildly neurotoxic at serum concentrations of 60 pg/mL and may be life-threatening at concentrations of 200 pg/mL. Other adverse effects of thiocyanate includes inhibition of both the uptake and binding of iodine producing symptoms of hypothyroidism. 

The interactions of ergot derivatives with erythromycin and troleandomycin are well documented, well establish, and clinically important, whereas information about clarithromycin appears to be eonfined to three possible cases and that relating to oleandomycin to one case. There are no adverse reports about midecamycin, but it is expected to interact similarly. The concurrent use of all of these macrolides and ergot derivatives should be avoided. Some of the cases cited were effectively treated with sodium nitroprusside or naftidrofuryl oxalate, with or without heparin. "" " Spiramycin, and josamycin would not be expected to interact because they do not inhibit CYP3A4. However, there is one unexplained and unconfirmed report of an interaction with josamycin. "... 

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