Re: what is the antidote for methoxsalen?

Susan,

I ran this question by a physician-scientist in our dermatology department, who writes:

"I don't think there's really a chemical "antidote" for methoxsalen, which is a psoralen. If someone were to overdose on psoralen, the treatment would be avoidance of UV light until the drug had been eliminated. I don't know the half-life of the drug, but it is safe to go outside after twenty four hours with a normal dose. You can also use a combination of clothing and sunscreen, but it would have to be UVA protection - also make sure to wear sunglasses."

I take this to mean that the "antidote," lack of UV light, would prevent the covalent crosslinking psoralen to DNA. In the context of your question this would mean that it would "suppress" the activity of psoralen.

However, she also added:

"Finally, one other point is that psoralen causes significant nausea - suggesting that there may be other, non-UVA activatable mechanisms of psoralen action (although I guess it's also possible that some nausea-producing toxin could be forming in the skin after light exposure. I don't know how psoralens are metabolized or excreted but you might be able to increase the rate of elimination of the drug by hydration, alkalinization of the urine, or revving up the P450 system."

I found a fairly complete description of methoxsalen at this site.

Best,

Jennifer

Jennifer Logan, Ph.D.
Genetic Science Learning Center
Eccles Institute of Human Genetics
University of Utah School of Medicine