Will Taking Sodium Thiosulfate Prevent Ototoxicity?

 

by Neil Bauman, Ph.D.

May, 2009 (Revised July, 2018)

 

A man wrote:

I was wondering if you had an opinion on a drug called STS (Sodium thiosulfate). It’s being developed to protect chemotherapy patients taking platinum-based anti-cancer drugs from hearing loss. Is this (STS) something that could be more broadly applied to the numerous drugs that could cause ototoxicity?

The research looks promising so far. It’s certainly possible that STS will help protect against hearing loss from some ototoxic drugs. Because different ototoxic drugs have different mechanisms of damage, the trick is to find an “antidote” that interacts specifically with each ototoxic drug.

I think more likely, that there will be different drugs found to protect hearing against specific classes of ototoxic drugs. For example, Sodium thiosulfate may work best for the platinum-based drugs such as Cisplatin, Carboplatin and Oxaliplatin.

Here are the results from one study. In a study of 99 children with hepablastoma and treated with Cisplatin alone, 67% had resulting hearing loss. However, resulting hearing loss in those children given the same Cisplatin treatment plus receiving sodium thiosulfate at the same time dropped to just 37%. The same results also held true for some other kinds of cancer as well.

Note: In June, 2018, the FDA granted Fennec Pharmaceuticals a “breakthrough therapy” designation to fast track their drug PEDMARK, a unique formulation of sodium thiosulfate, to help prevent ototoxic reactions in people taking Cisplatin. So it looks like soon there will be a way of combating, at least in part, ototoxicity due to taking Cisplatin and other platinum-based drugs.

For the aminoglycoside antibiotics, maybe iron chelators such as Deferoxamine will prove to be the ticket. Unlike how Cisplatin affects our ears, preliminary research indicates that aminoglycosides such as Gentamicin only are ototoxic when they react with iron found in the bloodstream. Thus, in this case, iron chelators that “soak up” excess iron in the bloodstream may prove to be the route to go. Another possibility is Aspirin taken with Gentamicin to do the same job.

In general, it seems that many ototoxic drugs produce free radicals that damage the hair cells and cause them to die. Thus, using free-radical scavengers to zap the free radicals before they can damage our hair cells is probably a good way to go as well. A couple of good, natural free-radical scavengers are N-acetyl-cysteine and glutathione.

What I took the long way around saying is that doctors need to research the exact mechanism that causes a drug to be ototoxic and then find the specific antidote. I think they will continue to come up with a number of specific antidotes as I’ve shown above, and also a number of general ones.

Unfortunately, few drugs are specifically studied to determine their ototoxic mechanisms. The notable exceptions are the platinum drugs and the aminoglycoside antibiotics. The rest get the short end of the stick, so it may be a long time before anyone finds a specific antidote for them. However, in general, the free-radical scavengers look like the most promising line of protection against ototoxicity available at this time.

To learn which drugs are (or can be) ototoxic, see “Ototoxic Drugs Exposed“. This book contains information on the ototoxicity of 877 drugs, 35 herbs and 148 chemicals.