Making drugs stick to your stomach.
Drug capsules and tablets can pass from the stomach andsmall intestine into the colon within three to four hours of swallowing, notes biophysicist David Harris. And though many drugs have been formulated to slowly release their ingredients over a longer period, not all are well absorbed through the colon. Harris and his colleagues at the University of Manchester in England are pursuing ways to prolong a drug's residence in the stomach by embedding a biodegradable "glue' into capsules of time-released drugs.
In trials with eight volunteers, the researchers tested mockdrugformulations containing a commercially available polymer --either Carbopol-934 or Polycarbophil--that had been shown in animal studies to adhere to the mucous lining of the stomach.
Though the Polycarbophil-based capsules broke down andbegan exiting the stomach in just 20 to 40 minutes, the Carbopol version in some cases remained for up to nine hours, Harris reports. However, he notes, even the Carbopol-based formulation "was not consistently effective.' There are cycles of high and low stomach-emptying activity. And during some of the high-activity periods, Harris says, even the Carbopol-based capsules had a hard time withstanding the stomach's emptying motions. The group is now working on which they believe is an improved formulation: Instead of just blending the bulk resin beads and adhesive powder in a gelatin capsule--hoping they will coalesce into a clumpy drug-glue matrix in the stomach-- they are now coating each resin bead with Carbopol. It's expected the beads will survive longer by adhering to the stomach lining individually.
Harris says these formulations could ultimately find use inextending the controlled release of drugs like thiazide diuretics and certain heart medicines.
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|Title Annotation:||using biodegradable glue to prolong a drug's residence in the stomach|
|Date:||Apr 18, 1987|
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