William G. Pitt

Ultrasonically Enhanced Drug Delivery

Most of our recent research has revolved around the use of ultrasound to enhance the action of drugs.  Our research group was the first to discover that the killing effect of many antibiotics is enhanced by the application of ultrasound.  Orders of magnitude more bacteria are killed when low frequency ultrasound is applied simultaneously with antibiotics.  We have studied the effect of ultrasonic frequency, power density, and wave form, and found that the enhanced killing (called the bioacoustic effect) increases with power density, decreases with increasing frequency, and is enabled by both continuous and pulsed waveforms.  We can apply this bioacoustic effect successfully against planktonic and biofilm forms of bacteria.  The bioacoustic effect has very important implications in the treatment of bacterial infections of medical implants.  In nearly all cases in which a bacterial biofilm has formed on the implant, the infection can never be cured, even by aggressive antibiotic therapy, and thus the implant must be removed and replaced.  This can be devastating to the patient if the implant happens to be an artificial hip or heart valve.  We hope to be able to apply this technology to eliminate bacterial infections on implants without resort to surgical procedures.  The ultrasound can be applied tot he infection non-invasively via a transducer on the skin.  Our current work is supported by the NIH and the Whitaker Foundation.  Please see our recent publications for more information.

In another application of ultrasound, we have found that anti-cancer drugs can be sequestered inside small micelles that can be injected into the blood stream and travel throughout the body.  The drug carriers keep the drug from being released and poisoning the body, resulting in the unwanted side effects of chemotherapy.  We have also discovered that we can selectively release the drugs from the carrier by the application of ultrasound.  We are actively studying this phenomena, and are designing and synthesizing drug carriers.  Our goal is to be able to make a drug carrier that will release the drug in the body only when activated by ultrasound.  In such a case, the ultrasound could be focussed on a tumor, and the drug would be released as the carriers floated through the acoustic field in the region of the tumor.  This has obvious advantages in cancer therapy.  This work is supported by the NIH and the NSF.  Please see our recent publications for more information.