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

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after you swallow it?

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Medicine that slides down[br]your throat can help treat a headache,

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a sore back,

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or a throbbing sprained ankle.

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But how does it get where it needs[br]to go in the first place?

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The answer is that it hitches[br]a ride in your circulatory blood stream,

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cycling through your body in a race[br]to do its job

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before it's snared by organs[br]and molecules designed to neutralize

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and expel foreign substances.

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This process starts [br]in your digestive system.

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Say you swallow an ibuprofen tablet[br]for a sore ankle.

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Within minutes, the tablet starts[br]disintegrating in the acidic fluids

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of your stomach.

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The dissolved ibuprofen travels[br]into the small intestine

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and then across the intestinal wall[br]into a network of blood vessels.

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These blood vessels feed into a vein,

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which carries the blood,[br]and anything in it, to the liver.

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The next step is to make [br]it through the liver.

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As the blood and the drug molecules[br]in it travel through liver blood vessels,

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enzymes attempt to react with [br]the ibuprofen molecules

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to neutralize them.

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The damaged ibuprofen molecules,[br]called metabolites,

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may no longer be effective as painkillers.

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At this stage, most of the ibuprofen[br]makes it through the liver unscathed.

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It continues its journey out of the liver,

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through veins,

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into the body's circulatory system.

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Half an hour after you swallow the pill,

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some of the dose has already made it[br]into the circulatory blood stream.

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This blood loop travels through every[br]limb and organ,

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including the heart, brain, kidneys,[br]and back through the liver.

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When ibuprofen molecules [br]encounter a location

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where the body's pain [br]response is in full swing,

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they bind to specific target molecules[br]that are a part of that reaction.

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Painkillers, like ibuprofen, block the[br]production of compounds

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that help the body transmit pain signals.

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As more drug molecules accumulate,

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the pain-cancelling affect increases,

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reaching a maximum within about[br]one or two hours.

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Then the body starts efficiently [br]eliminating ibuprofen,

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with the blood dose decreasing by half[br]every two hours on average.

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When the ibuprofen molecules detach[br]from their targets,

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the systemic blood stream carries[br]them away again.

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Back in the liver, another small fraction[br]of the total amount of the drug

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gets transformed into metabolites,

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which are eventually filtered out[br]by the kidneys in the urine.

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The loop from liver to body to kidneys[br]continues at a rate

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of about one blood cycle per minute,

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with a little more of the drug neutralized[br]and filtered out in each cycle.

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These basic steps are the same for[br]any drug that you take orally,

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but the speed of the process

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and the amount of medicine that makes[br]it into your blood stream

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varies based on drug,

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person,

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and how it gets into the body.

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The dosing instructions [br]on medicine labels can help,

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but they're averages based on [br]a sample population

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that doesn't represent every consumer.

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And getting the dose right is important.

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If it's too low, [br]the medicine won't do its job.

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

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That's true of any drug.

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One of the hardest groups of patients[br]to get the right dosage for are children.

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

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For instance, the level of liver enzymes[br]that neutralize medication

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highly fluctuates [br]during infancy and childhood.

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And that's just one [br]of many complicating factors.

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Genetics,

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age,

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diet,

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disease,

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and even pregnancy influence the body's[br]efficiency of processing medicine.

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

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personalized to your liver efficiency[br]and other factors,

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but in the meantime,

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your best bet is reading the label

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or consulting your doctor[br]or pharmacist,

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and taking the recommended amounts[br]with the recommended timing.