Sodium thiosulfate is not the first drug you think of when
asked to reel off a series of medications. Yet, it is a versatile,
underappreciated agent that can on occasions be lifesaving.
One of its foremost roles is in cyanide poisoning. When you
think of cyanide, you invariably conjure up images of the Agatha Christie type
pill in the cup of tea type scenario. Yet, that sort of cyanide, usually KCN,
is rarely available, and most cases of cyanide poisoning occur to due to smoke
inhalation in people caught in fires, from hydrogen cyanide. Here, the three
most useful agents are sodium thiosulfate, sodium nitrite and good, old-fashioned
vitamin B12- hydroxocobalamin.
You may have heard of cisplatin induced hearing loss? This
is particularly problem in paediatric oncology, where IV cisplatin is given to
treat a hepatoblastoma, for example. Yet, by limiting cisplatin infusion time
to 6 hours, and giving IV sodium thiosulfate within 6 hours of cisplatin, you
can reduce the incidence of cisplatin induced hearing loss in these children.
Sodium thiosulfate is particularly useful where vascular
calcification leads to troublesome complications such as skin ulcerations in
fatty areas in patients with advanced CKD, known as calciphylaxis, or where a
rare autosomal recessive disorder called ACDC exists.
ACDC is admittedly rare. It is an inherited, autosomal recessive
disorder where relatively young subjects in their 40s and 50s present with
severe limb claudication, ischaemic ulcers, critical limb claudication & joint
pains in hands and feet. The hallmark is calcification of arteries such as
iliac, femoral and tibial arteries, but sparing the aorta, which is very unlike
atherosclerosis, which ACDC is often confused with.
ACDC stands for “arterial calcification with deletion of
CD73”. You may remember that CD73 converts cyclic AMP to adenosine. Apparently,
this leads to higher levels of tissue non-specific alkaline phosphatase
downstream, and ectopic calcification. Apart from arterial calcification, you
also get periarticular calcification, which can be a clue.
Again, IV sodium thiosulfate in such subjects can be limb
sparing.
