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  • Have you ever wondered what happens to a painkiller, like ibuprofen,

  • after you swallow it?

  • Medicine that slides down your throat can help treat a headache,

  • a sore back,

  • or a throbbing sprained ankle.

  • But how does it get where it needs to go in the first place?

  • The answer is that it hitches a ride in your circulatory blood stream,

  • cycling through your body in a race to do its job before it's snared by organs

  • and molecules designed to neutralize

  • and expel foreign substances.

  • This process starts in your digestive system.

  • Say you swallow an ibuprofen tablet for a sore ankle.

  • Within minutes, the tablet starts disintegrating in the acidic fluids of your stomach.

  • The dissolved ibuprofen travels into the small intestine

  • and then across the intestinal wall into a network of blood vessels.

  • These blood vessels feed into a vein,

  • which carries the blood, and anything in it, to the liver.

  • The next step is to make it through the liver.

  • As the blood and the drug molecules in it travel through liver blood vessels,

  • enzymes attempt to react with the ibuprofen molecules

  • to neutralize them.

  • The damaged ibuprofen molecules, called metabolites,

  • may no longer be effective as painkillers.

  • At this stage, most of the ibuprofen makes it through the liver unscathed.

  • It continues its journey out of the liver,

  • through veins,

  • into the body's circulatory system.

  • Half an hour after you swallow the pill,

  • some of the dose has already made it into the circulatory blood stream.

  • This blood loop travels through every limb and organ,

  • including the heart, brain, kidneys, and back through the liver.

  • When ibuprofen molecules encounter a location

  • where the body's pain response is in full swing,

  • they bind to specific target molecules that are a part of that reaction.

  • Painkillers, like ibuprofen, block the production of compounds

  • that help the body transmit pain signals.

  • As more drug molecules accumulate,

  • the pain-cancelling affect increases,

  • reaching a maximum within about one or two hours.

  • Then the body starts efficiently eliminating ibuprofen,

  • with the blood dose decreasing by half every two hours on average.

  • When the ibuprofen molecules detach from their targets,

  • the systemic blood stream carries them away again.

  • Back in the liver, another small fraction of the total amount of the drug

  • gets transformed into metabolites,

  • which are eventually filtered out by the kidneys in the urine.

  • The loop from liver to body to kidneys continues at a rate

  • of about one blood cycle per minute,

  • with a little more of the drug neutralized and filtered out in each cycle.

  • These basic steps are the same for any drug that you take orally,

  • but the speed of the process

  • and the amount of medicine that makes it into your blood stream

  • varies based on drug,

  • person,

  • and how it gets into the body.

  • The dosing instructions on medicine labels can help,

  • but they're averages based on a sample population

  • that doesn't represent every consumer.

  • And getting the dose right is important.

  • If it's too low, the medicine won't do its job.

  • If it's too high, the drug and its metabolites can be toxic.

  • That's true of any drug.

  • One of the hardest groups of patients to get the right dosage for are children.

  • That's because how they process medicine changes quickly, as do their bodies.

  • For instance, the level of liver enzymes that neutralize medication

  • highly fluctuates during infancy and childhood.

  • And that's just one of many complicating factors.

  • Genetics,

  • age,

  • diet,

  • disease,

  • and even pregnancy influence the body's efficiency of processing medicine.

  • Some day, routine DNA tests may be able to dial in the precise dose of medicine

  • personalized to your liver efficiency and other factors,

  • but in the meantime,

  • your best bet is reading the label

  • or consulting your doctor or pharmacist,

  • and taking the recommended amounts with the recommended timing.

Have you ever wondered what happens to a painkiller, like ibuprofen,

Subtitles and keywords

B2 H-INT US ibuprofen liver blood drug medicine body

【TED-Ed】How does your body process medicine? - Céline Valéry

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    Anita Lin   posted on 2017/05/17

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