How long does it take an extended release pill to be completely disolved into your bloodstream?

May 11, 2007 7:57 AM

How long does it take an extended release pill (specifically Adderall XR) to be completely disolved into your bloodstream?

The matter is mostly academic now... (possibly TMI here) About three hours ago I took 20mg of Adderall XR (actually, two 10mg capsules, if it makes a difference) as usual. Just now I decided to take a multivitamin. On an empty stomach. Needless to say, it came right back up, with everything else in my stomach (which wasn't much.)

So my question is, would three hours be enough time for the Adderall to have dissolved into my bloodstream? I read somewhere that the little granules in the XR version are coated with something that takes longer to dissolve, to achieve the extended effect. Is this true, and would that mean that some of the medicine was probably still in my stomach, undissolved after three hours?

posted by catatethebird to science & nature (6 comments total)

Or does it enter the bloodstream quickly, and then the drug is slowly released while it's already in the blood? I really don't know too much about this kind of stuff, but it seems really interesting.
posted by catatethebird at 8:04 AM on May 11, 2007

Adderall XR utilizes the Microtrol® delivery system to achieve the extended-release mechanism. This delivery system incorporates two beads: the first type of bead dissolves immediately and the second type releases four hours later. Maximum plasma concentration is achieved in seven hours.
posted by sanko at 8:04 AM on May 11, 2007

Since the pKa of amphetamine is above 9 (due to the aminogroup), the majority of the absorption to the blood takes place in the intestine, not in the acidic environment of the stomach. I don't know, however, if three hours would be enough for the pill/beads to get to the intestine and be safe from regurgitation, though.

Do you have a pharmacist you could call to ask advice on whether it's okay to take another 10mg? Or is this a day you can chance it and not get the meds?
posted by twoporedomain at 8:39 AM on May 11, 2007

The Adderall XR had surely passed out of your stomach and into your intestines by the time you puked.
posted by caddis at 8:40 AM on May 11, 2007

I figured that most, if not all was already dissolved. I don't think I need to double dose. Thanks for the replies, the science of it is really interesting.
posted by catatethebird at 8:53 AM on May 11, 2007

The manufacturer's information says that if you miss a dose, don't double dose, just take the next dose at the regular time. Since at most you only lost a small percentage of the dose by upchucking, just stay on your normal dosing schedule.

Everyone else has already answered your question adequately, but I'm a pharmacy student and I find this kind of question fun so I had to chime in. Adderall XL is essentially 2 doses in one - as stated above, half of it goes into your bloodstream right away (reaching peak concentration in 3 hrs) and the other half doesn't dissolve till later, reaching peak in 7 hrs. The main reason for this formulation was so kids with ADHD could take just one tablet in the morning, and not have to take one while at school.
posted by selfmedicating at 10:33 AM on May 11, 2007