Two Tylenol every 4 hours or one Tylenol every 2 hours?

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Pewl

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Ok, so I had this raging fever a couple days ago, and I wondered, for fever-relief is it better to take two Tylenol every four hours as directed and would it make much of a difference to take one Tylenol every two hours after the initial two?

This may be some insane fever-induced reasoning, but I figure you need a certain concentration of acetaminophen in your bloodstream to get that anti-pyretic effect. But, if you took one every two hours after the initial two simultaneous caplets would you avoid the drop in concentration of acetaminophen in your blood?

Heh, anyone have any ideas? =P
 
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Pewl said:
Ok, so I had this raging fever a couple days ago, and I wondered, for fever-relief is it better to take two Tylenol every four hours as directed and would it make much of a difference to take one Tylenol every two hours after the initial two?

This may be some insane fever-induced reasoning, but I figure you need a certain concentration of acetaminophen in your bloodstream to get that anti-pyretic effect.

In a word, pharmacokinetics. ;)
 

VCU07

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Pewl said:
Ok, so I had this raging fever a couple days ago, and I wondered, for fever-relief is it better to take two Tylenol every four hours as directed and would it make much of a difference to take one Tylenol every two hours after the initial two?

This may be some insane fever-induced reasoning, but I figure you need a certain concentration of acetaminophen in your bloodstream to get that anti-pyretic effect. But, if you took one every two hours after the initial two simultaneous caplets would you avoid the drop in concentration of acetaminophen in your blood?

Heh, anyone have any ideas? =P

If your talking about general OTC Tylenol the package specifies 2 tablets q4hrs. This is due, in part, to the way the manufacturers of Tylenol submitted their research to the FDA (i.e. this dosage regimen produced the best results). If you wanted to take 1 tablet q2hrs it may not make a big difference because the elimination t1/2 of tylenol is around 2hrs, but you may not reach therapeutic concentrations with only 1 tab. On the other hand, taking 2 tabs q4hrs will be what gets you in the theraputic range (i.e. b/n the MIC, but below the toxic concentrations). Also, realize this depends on what mg tylenol you take. Basically, taking 1 tab q2 hrs would be like jumping high enough to almost pull off a slam dunk, while taking the 2 tabs will help you get just high enough to slam it. Hope that helped.
 
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sdn1977

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VCU07 said:
If your talking about general OTC Tylenol the package specifies 2 tablets q4hrs. This is due, in part, to the way the manufacturers of Tylenol submitted their research to the FDA (i.e. this dosage regimen produced the best results). If you wanted to take 1 tablet q2hrs it may not make a big difference because the elimination t1/2 of tylenol is around 2hrs, but you may not reach therapeutic concentrations with only 1 tab. On the other hand, taking 2 tabs q4hrs will be what gets you in the theraputic range (i.e. b/n the MIC, but below the toxic concentrations). Also, realize this depends on what mg tylenol you take. Basically, taking 1 tab q2 hrs would be like jumping high enough to almost pull off a slam dunk, while taking the 2 tabs will help you get just high enough to slam it. Hope that helped.

Actually, you have a bit of misinformation. There is no MIC for acetaminophen. MIC is the minimum inhibitory concentration and is used in reference to antimicrobials and refers to the concentration in whatever tissue you are testing (blood, urine, CSF, etc...) The actual antipyretic action is a result of a direct action on the hypothalamic heat regulating centers & as yet there is no correlation between blood levels and antipyretic activity. To evaluate what dose to take, we consider the absorption, distribution & protein binding. Peak plasma levels occur within 30min-2hrs with liquid being slightly faster. Absorption is complete within 4 hours. Serum protein binding ranges between 20-50% & remember, it is only unbound drug which is active. This is & the volume of distribution which can be between 5-20mcg/ml are the variables which determine what dose will work. Generally, the recommendations are 650mg (325mg if you are a small adult) = 2 regular strength acetaminophen, every 4-6hrs will give you relief. Now...most acetaminophen is extra strength - 500mg/unit so many folks will take 1000mg every 4-6hrs. Thats ok too (unless you are a small adult-then take 1) - you'll saturate all your protein binding sites & leave enough for lowering your fever. BUT....you've got to be careful because acetaminophen is really toxic to your liver - you should not exceed 4G/day for an acute illness & acetaminophen blood levels are highly tied to toxicity - we acetylcysteine for overdosage based upon blood levels. If you are taking any other drug toxic to the liver (ie..your hot toddy for your sore throat & congestion ;) ) - take a lower dose of acetaminophen. So..take a therapeutic dose less frequently rather than a lower dose more frequently (unless you are a neonate in which case...we dose entirely differently) I'm a pharmacist, so thats probably more info than you want, but I do like drugs!
 

VCU07

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sdn1977 said:
Actually, you have a bit of misinformation. There is no MIC for acetaminophen. MIC is the minimum inhibitory concentration and is used in reference to antimicrobials and refers to the concentration in whatever tissue you are testing (blood, urine, CSF, etc...) The actual antipyretic action is a result of a direct action on the hypothalamic heat regulating centers & as yet there is no correlation between blood levels and antipyretic activity. To evaluate what dose to take, we consider the absorption, distribution & protein binding. Peak plasma levels occur within 30min-2hrs with liquid being slightly faster. Absorption is complete within 4 hours. Serum protein binding ranges between 20-50% & remember, it is only unbound drug which is active. This is & the volume of distribution which can be between 5-20mcg/ml are the variables which determine what dose will work. Generally, the recommendations are 650mg (325mg if you are a small adult) = 2 regular strength acetaminophen, every 4-6hrs will give you relief. Now...most acetaminophen is extra strength - 500mg/unit so many folks will take 1000mg every 4-6hrs. Thats ok too (unless you are a small adult-then take 1) - you'll saturate all your protein binding sites & leave enough for lowering your fever. BUT....you've got to be careful because acetaminophen is really toxic to your liver - you should not exceed 4G/day for an acute illness & acetaminophen blood levels are highly tied to toxicity - we acetylcysteine for overdosage based upon blood levels. If you are taking any other drug toxic to the liver (ie..your hot toddy for your sore throat & congestion ;) ) - take a lower dose of acetaminophen. So..take a therapeutic dose less frequently rather than a lower dose more frequently (unless you are a neonate in which case...we dose entirely differently) I'm a pharmacist, so thats probably more info than you want, but I do like drugs!

I meant to put maximum theraputic concentration, not MIC-I was just studying ID lol. Anyway, I do have to disagree with something you said. Tylenol does work to regulate body temperture in the brain, but it does so by reaching some concentration in the blood. Finally, per MMDX there is a min level that needs to be obtained in blood to exert its effects.
 

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Soooo, asking for medical advice isn't allowed on SDN. Therefore, I'm gonna close this thread...
 
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