Extended and Delayed Release Medications: Using Technology to Increase Medication Compliance

Time released medications are more frequent in medicine today and are a useful dosage form for patients and providers. While they are usually at least slightly more expensive than their immediate release counterparts, they reduce the dosage frequency and increase the likelihood of medication compliance.

Time released medications are available in just about every therapeutic class on the market - from urinary incontinence to pain management, seizures and psychosis, to hypertension and diabetes.

 There are a number of abbreviations that indicate that a medication is some sort of extended or delayed release.

• Sustained Release (SR)
• Sustained Action (SA)
• Extended Release (XR, XL, ER)
• Time(d) Release (TR)
• Controlled Release (CR)
• Modified Release (MR)
• Continuous Release (CR or Contin)
• Long-Acting (LA)
• Delayed Release (DR)
• Enteric Coated (EC)

Methods of Altering the Release Mechanism

Microencapsulation involves coating a small core of medication and coating it with insoluble materials. This is the method used for extended or delayed release capsules (though the layers of materials differ). This is particularly useful for mixing extended and immediate release materials within a single capsule.

Certain materials are not digestible by the human digestive tract. These include chitin, a product common in shell fish that give them their hard shells. Synthetic materials can now be used, but the mechanism is the same. Stomach acids filter through small holes in the non-digestible membrane and the drug slowly filters back out. Some medications make an entire shell of this with only a small, laser-drilled hole for the medication to escape. With medications like these, it is not uncommon for patients to see what looks like a full, undigested tablet in their feces. The tablet has, in fact, been completely emptied of it's contents and only the indigestible shell remains.

Enteric coating  involves coating the capsule or tablet in a coating that is stable at acidic pHs (as are present in the stomach). As the pH rises when the tablet or capsule enters the small intestine, the coating breaks down and the medication in released. Many proton pump inhibitors (PPIs) like Prevacid (lansoprazole) and Prilosec (omeprazole) are available like this, as well as aspirin. This enteric coating causes a medication to be known as "delayed release" since the actual release of the medication is put off for a hour or more until it is moved to the small intestine. This is particularly useful for medications, like PPIs, which would be destroyed by the acidic environment in the stomach or for medications that are damaging to the stomach, like aspirin or naproxen.

Special Administration Considerations

As noted above, it may be prudent to warn patients that they may see what appears to be a full tablet in their feces. It is also important to counsel patients not to crush, chew or break their medication as this may alter the  effectiveness. If a patient is switching from an immediate release dosage form to an extended release, they should be made aware that they're likely going to be taking it less frequently than they were before.

It is also important to note that that extended release medications are rarely used for acute indications. For example, immediate relief morphine can be used as needed for pain, while extended release morphine cannot.

Until next time,
C. Samuels

Resources
"Patient Advice Label: Do Not Crush." Total Pharmacy Supply. Web. 01 Jun 2011. <http://shop.tps-online.com/browse.cfm/4,3738.html>.


Wikipedia contributors. "Enteric coating." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 24 Apr. 2011. Web. 2 Jun. 2011.


Wikipedia contributors. "Time release technology." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 12 Mar. 2011. Web. 2 Jun. 2011.