Harnessing the Power of Electrostatics

Telko works to improve dry powder inhaler technology

A graduate student in the School of Pharmacy since 2004, Telko has earned a number of awards, including the UNC Scholars for Tomorrow Fellowship in Computational Sciences, the United States Pharmacopeia Graduate Fellowship, and the PhRMA Foundation PreDoctoral Fellowship in Pharmaceutics. He also received the Outstanding Graduate Student Award from the Division of Molecular Pharmaceutics in 2007.

From Xerox machines to automotive painting, electrostatic technology is used in a number of industries to increase efficiency. Graduate student Martin Telko hopes he can help harness the benefits of electrostatics for the delivery of drug from dry powder inhalers.

Electrostatics is an area of science that deals with static electrical charges. People encounter electrostatic charging in everyday life, like when plastic wrap sticks to someone’s hand or when lightning flashes across the sky.

Electrostatics plays a key role in photocopiers, where a selectively charged drum inside the machine attracts toner particles and fuses them onto a sheet of paper. Electrostatic painting is used on most automobiles, in a process where dry powder applied through a charged spray gun is firmly attracted to the grounded car and then fused into a smooth coating.

In the pharmaceutical inhaler industry, however, electrostatics has not yet been fully exploited. Telko, a graduate student in the Division of Molecular Pharmaceutics, is hoping to use electrostatics to improve the delivery of drugs to the respiratory tract through the use of dry powder inhalers. Telko’s adviser is Professor Anthony Hickey, PhD, DSc, whose lab is focused on microparticulate drug delivery systems and pharmaceutical aerosols.

Dry powder inhalers have emerged as an alternative to traditional metered-dose inhalers.

To date, the most successful dry powder inhaler product is Advair, containing asthma drugs marketed by GlaxoSmithKline. Advair is one of the most successful drug products by any measure, and its sales are expected to top $9 billion in 2010.

Telko says traditional metered-dose inhalers are sometimes difficult for patients to use and have traditionally contained ozone-depleting propellants. Although propellant materials have been replaced with more environmentally friendly alternatives, the inhalers still contain greenhouse gases, Telko says.

Dry powder inhalers have several advantages over metered-dose inhalers, Telko says. They don’t use any type of propellant to administer the drug, making them environmentally safe. In addition, some patients find dry-powder inhalers easier to use. The drug contained in them also tends to be more stable.

But with that stability comes a level of complexity. In order for drugs to be delivered to the human lung, the drug particles need to be very small in size (five micrometers). If the particles are larger than that, they get deposited in the back of the throat when inhaled and don’t reach their intended target. But the smaller the particle, the bigger the problems.

“The challenge is that particles so small have a lot of obstacles to overcome,” Telko says. “They have large surface area and tend to agglomerate, so it becomes hard to keep them apart. Several dry powder inhaler products have failed or have been withdrawn because the separation of particles hasn’t been very good.”

According to the Food and Drug Administration, a number of complex interactions can occur in dry powder inhalers that significantly alter the safety and effectiveness of a drug. These include gravitational, fluid dynamic, van der Waals, electrostatic, and capillary forces.

Telko is interested in the electrostatic interactions that occur, an area that hasn’t been extensively examined.

Hickey’s lab has an ongoing collaboration with Dekati, a Finnish company that manufactures fine particle measurement instruments for a wide range of measurement needs. The company developed a device that uses electrostatic forces in aerosol sampling and classification. Telko and Hickey have modified the device so that they can specifically study electrostatic forces in medicinal aerosols. Telko has designed experiments and devised various formulations to test in the device.

The ultimate goal, Telko says, is to understand the factors that contribute to the charging phenomena and learn to predict the electrostatic charges and develop systems where conditions are optimized.

“Essentially, the small particles found in dry-powder inhalers are going to have some charging phenomena,” Telko says. “The issue is to understand how it comes about, what contributes to it, and how we can use it to our advantage.”

To do this, he is exploring all aspects of the dry powder inhalers, including device design and formulation. While device design is obvious to anyone who looks at an inhaler, the formulation inside the design is often less apparent.

“These formulations appear simple, but the forces of interaction are very complex, and we’ve only begun to understand some of the aspects that are at play here,” Telko says.