Melting corks allow for temperature-controlled release of drugs from microscale vessels
Sustained-release formulations that release drugs over longer periods of time are not the final step in the evolution of “intelligent” drug delivery systems. Modern pharmaceuticals are being designed to be released only in a specific, diseased organ; on cues from our circadian rhythm; or under specific physiological conditions. In the journal Angewandte Chemie, a team of American and Korean researchers has now introduced “microbottles” with “corks” that release their contents only when the temperature rises above a defined level.
Our circadian rhythms can cause our reaction to a drug to vary with time. Certain conditions and symptoms can also fluctuate with our circadian rhythm. Some pharmaceuticals, such as beta blockers, chemotherapy drugs, and cortisone treatments thus come with recommendations for timing doses. The “intelligent” control drug release based on changing physiological conditions is an extension of these ideas.
Temperature in particular could be a useful regulator for such systems. Our body temperature varies throughout the day and in response to certain physiological states or phases, like disease. An “intelligent” blood pressure reducing drug could be released when body temperature and blood pressure rise due to stress. Inflammation usually causes the temperature of the affected area to rise, so a drug could be directed only to these hot areas. Alternatively, a diseased area of the body, such as a tumor, could be locally warmed to release chemotherapy drugs on the spot, causing fewer side effects.