Liquid salts could make topical drugs more effective, safe

The formulations reduced the toxicity of some drugs when applied to skin, which researchers say could help improve drug delivery and efficacy.
By Stephen Feller   |   Dec. 29, 2015 at 5:13 PM

SANTA BARBARA, Calif., Dec. 29 (UPI) -- Formulating drugs as liquid salts may help limit the toxicity of some topical drug formulations, while also making them more effective, according to a new study by researchers at the University of California, Santa Barbara.

Many drugs are dissolved in organic solvents in order to be used topically, however these solvents are often toxic, and some drugs themselves are toxic to the skin in certain quantities.

Previous studies have shown liquid salts may aid drug transport through the skin, but UCSB researchers said they are the first to develop liquid salts with the goal of reducing toxicity.

Researchers tested the theory with propanolol, a beta blocker used to treat high blood pressure, chest pain, tremors and migraines. The drug is also charged, and toxic to skin, a problem researchers said may be solved by using it as a liquid salt, formulated with counter ions.

"Propranolol is positively charged which is a likely source of its toxicity," said Dr. Samir Mitragotri, a researcher at the University of California Santa Barbara, in a press release. "Shielding of this charge by association with a counter species in the liquid salt reduces its toxicity. These findings are broadly applicable to many charged drugs."

In the study, published in the journal Technology, researchers tested liquid salt melt formulations on pig skin for toxicity and distribution of drugs.

While tests did show reduced toxicity, researchers wrote variations in hydration can affect both handling of the drug and skin irritation and should be explored in future research. They also note hydration of individual's skin, and humidity of location, can affect the formulations.

Nonetheless, they write formulating topical drugs as liquid salts shows promise for improving delivery.

"This technology presents an exciting new, patient compliant solution for treating diseases," said researcher Michael Zakrewsky.

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