Nothing up his sleeve: Decompensation after bariatric surgery
Mr. G, age 64, has schizoaffective disorder and has been stable for years. Weeks after undergoing bariatric surgery, he rapidly develops depressive symptoms. What could be the cause?
The authors’ observations
The key component to creating a treatment plan for Mr. G centered on understanding drug metabolism and delivery. Acidity plays a role in dissolution of many medications, which led the team to surmise that the PPI, omeprazole, was the culprit. Through research, they understood that the divalproex sodium ER formulation needed a more acidic environment to dissolve, and therefore, an IR formulation was needed.
Different formulations, different characteristics
Medications can be produced in different formulations such as IR, delayed-release (DR), and ER formulations. Different formulations may contain the same medication at identical strengths; however, they may not be bioequivalent and should be titrated based on both the properties of the medication and the release type.1
Immediate-release formulations are developed to dissolve without delaying or prolonging absorption of the medication. These formulations typically include “superdisintegrants” containing croscarmellose sodium2 so that they disintegrate, de-aggregate, and/or dissolve when they come into contact with water or the gastrointestinal tract.3-7
Delayed-release formulations rely on the gastrointestinal pH to release the medication after a certain amount of time has elapsed due to the enteric coating surrounding the tablet. This enteric coating prevents gastric mucosa/gastric juices from inactivating an acid-labile medication.8
Extended-release formulations, such as the divalproex sodium ER that was originally prescribed to Mr. G, are designed to release the medication in a controlled manner over an extended period of time, and at a predetermined rate and location following administration.8-9 The advantage of this type of formulation is that it can be used to reduce dose frequency and improve adherence.10 Extended-release formulations are designed to minimize fluctuations in serum drug concentration between doses,11 thereby reducing the risk of adverse effects.12,13 A list of some common extended-release psychiatric medications is shown in the Table.
Continue to: The 5 oral formulations...
