I’ve just started an antibiotics course which is 4 times a day for 10 days and that got me wondering if they would be just as effective if I took them all and why not.
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There are couple words used to describe medicines approach to a drug regimen that i think are helpful to understanding this. The first word is Pharmacokinetics. You body absorbs, distributes,
metabolizes and excretes the drug at a rate specific to the drug, the concentration of the drug and is even unique to the individual to an extent. These competing additions and subtractions of the drug need to be considered, because the goal is to keep the concentration of the drug in the second important vocabulary word: the therapeutic range.
There is a certain concentration a drug that needs to be in your blood so that it has the desired effect, but there is also a concentration that will lead to undesirable side effects. If the drug is actually viable, the effective concentration should be less then the concentration that causes the adverse response.
With regard to antibiotics, we want them to basically kill off all of the pathogens, because leaving a small amount left, the infection could re-emerge. But not only that, the generations of bacteria that grow after the insufficient treatment of antibiotics would be the offspring of the bacteria that the antibiotics didn’t kill as easily. So natural selection makes the next use of that drug less effective.
So since we want to make sure we kill all the bacteria, we want the drugs to be above the effective range for a long time (maybe 10 days depending on the drug and pathogen.) But if you gave a dose so high that it stayed in the blood that long, not only would it be wasting drug because of the pharmacokinetics of it, but more importantly, it would be way above the therapeutic range and cause the adverse side effects.
Hope that’s clear, I know it’s ELI5, but i think the big science words can be helpful when they’re descriptive.
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