The Fantastic Voyage: “Submarines” Set Sail For New Drug Delivery

Courtesy Photo | Stock image for JSTO in the News.  

FORT BELVOIR, VA, UNITED STATES

03.06.2017

Courtesy Story

Defense Threat Reduction Agency's Chemical and Biological Technologies Department

What if humans could shrink to microscopic sizes and set sail on a “Fantastic Voyage” inside the human body to deliver life-saving drugs and repair ailments? This 1960’s sci-fi movie scene is not quite a reality, but the Dynamic Transport Materials basic research program of the Defense Threat Reduction Agency’s Joint Science and Technology Office is now using micromotors or “submarines” to sail through the digestive track to deliver life-saving drugs. One of the goals of this program is to advance the development of targeted delivery systems for medical countermeasures ensuring the health and safety of warfighters exposed to chemical and biological threats.

Sometimes the human body’s normal, useful processes and effective internal compounds, such as the stomach’s gastric acid, do not interact well with certain therapeutics. Though gastric acid is useful for digestion and protection from pathogens, it can be destructive to orally administered, pH-sensitive pharmaceuticals, including protein-based drugs and some antibiotics. A new method developed has the potential to significantly advance drug delivery systems and builds on the original method for treating stomach diseases with acid-sensitive drugs.

DTRA performers at the University of California, San Diego revealed their newly developed synthetic drug delivery method for treating stomach diseases with acid-sensitive drugs. The treatment consists of synthetic micromotors, or nanomachines, that act like tiny submarines speeding independently through the stomach, using gastric acid for fuel (while rapidly neutralizing it), and releasing their cargo precisely at the desired pH. The technique is based on proton-driven micromotors with a pH-dependent polymer coating that can be loaded with drugs.

A coating resistant to gastric acid is sufficient to protect medicines intended to work in the intestines. However, if a drug needs to be activated in the stomach, it is usually combined with proton pump inhibitors to block acid production. When used over longer periods, this can cause adverse effects in patients including headaches, diarrhea, fatigue, and in some severe cases, anxiety, depression, or rhabdomyolysis (a muscle disease).

With their micromotors, DTRA’s Dynamic Transport Materials program, managed by Dr. Brian Pate, has developed and introduced a novel approach for the neutralization of gastric acid that avoids side-effects and simultaneously acts as a drug transport mechanism that releases its cargo only when the optimal pH is reached.

An electrochemical reaction occurs on a small, uncoated spot on the pill, releasing tiny bubbles of hydrogen gas. These bubbles propel the motors, resulting in an effective mixture that causes the reaction to proceed rapidly. In less than 20 minutes after administering, the stomach environment reaches a neutral pH value, dissolving the polymer and releasing the drug payload. In addition, the propulsion furthers penetration of the micro-transporter into the gastric mucosa, which increases the amount of time that the payload is retained in the stomach; the normal pH value is re-established within 24 hours.

DTRA’s effort in advancing drug delivery systems is a novel millstone that may extend beyond the warfighter to public health, as this research can be applied to additional therapeutics. These micromotors hold promise for advanced targeted medical countermeasures to ensure the warfighter will sail to safe recovery if exposed to biological and chemical threats.

For more information, visit the Angewandte Chemie article, “Micromotors Spontaneously Neutralize Gastric Acid for pH-Responsive Payload Release.”

POC: Dr. Brian Pate; [e-mail]

• Date Taken: 03.06.2017
• Date Posted: 03.06.2017 10:10
• Story ID: 225807
• Location: FORT BELVOIR, VA, US