How reliable is enteric coating on capsules?

Question

Some probiotics are labelled "gastro resistant coating". Based on my limited knowledge and research, they are enteric capsules and they work based on changing PH in the GI tract.

The first thing that's strange to me is that based on the diagrams I see, the small intestine has neutral PH, and my research tells me enteric capsules need alkaline conditions to break down. (I guess this is more of a curiosity, since I assume drug makers know what they're doing.)

My question is, is it possible for a capsule to release its contents in the wrong spot? E.g further down the small intestine, or in the large intestine?

Answer 1

Without any knowledge about your personal medical condition, nor any intention to address your personal case (your indigestion, gastric/intestinal pH etc., simply because we cannot and should not, as specified in the right-hand yellow disclaimer and the tour), I would like to address the issue of enteric coating in general:

Since oral solid dosage forms (tablets, capsules) pass through the stomach on their way to the small intestine to be absorbed into the blood, if they contain an active ingredient that is acid-labile (i.e., may break down in an acidic environment such as the one in the stomach - pH level of 1-3), it is important to help it remain intact until it reaches the duodenum, where the pH is more basic (but not necessarily alkaline, i.e. larger than 7 - this is time- and place-dependent across the duodenum-small intestine axis).

Manufacturers protect acid-labile active ingredients in oral solid dosage forms through a variety of methods, most commonly enteric coating, which is a coating around the tablet or capsule that resists breakdown in the stomach but breaks down and releases the solid dosage form to disintegrate and liberate the active ingredient in the duodenum or further down the gastrointestinal system.

For reference, any basic pharmacy book should explain this concept. The Wikipedia entry on enteric coating can also be of assistance (which perhaps you should have read before posting your question).