Questions about peak and trough levels??

[stnurse2008]

This is probably a stupid question but can anyone explain to me about peak and trough levels. I had a pharmacology class last sememster but now I can't seem to remember and it was explained in a confusing way by the instructor. Any help would be appreciated!

[meownsmile, BSN, RN]

Trough levels arent as important as peak. Peak levels are done to ensure a patient is getting a theraputic level of medication but not becoming toxic and causing hearing or kidney damage. Peaks at my facility are done 30min to 1 hour after completion of every 3rd dose. Then pharmacy adjusts dosage as needed.

[wooh, BSN, RN]

Some meds have a very small range between working and toxic. The trough is done before you give the dose (the lowest the level gets in your bloodstream) to make sure you've got enough sticking around to work. The peak is done after the dose (the highest the level will get in your bloodstream) to make sure you aren't getting so much that it's toxic.

[hrtprncss]

In our facility, when the pharmacist initiates and controls the dosages, most of the time about 95 percent of the time, they don't do peaks. Only troughs. They will specify wether to wait for the trough to come back before hanging the next dose, or hang it after you draw it. This is about 50/50 of the time. If the trough is high, then they will adjust time administration let's say from q12 to q18. I haven't seen much peaks done and then dose adjustments, sometimes they do change the dose and the time as well based on the trough level.

EDIT: spell check

[stnurse2008]

Thanks for the replies that helps so much :)

[allele, LPN]

Trough levels arent as important as peak. Peak levels are done to ensure a patient is getting a theraputic level of medication but not becoming toxic and causing hearing or kidney damage. Peaks at my facility are done 30min to 1 hour after completion of every 3rd dose. Then pharmacy adjusts dosage as needed.

Everyone has given you great information, but I have to disagree that troughs are not as important as peaks. In fact, the infectious disease docs rarely even check peaks with certain drugs, like vancomycin. When you think about it, troughs are the lowest levels of drug in your system during therapy...and many drugs are toxic. If you draw a trough on, say, vancomycin, right before the next dose and it comes back high, then you've got a high level of a nephrotoxic/ototoxic drug in your system all the time. Low trough levels can also be dangerous. For example, epileptics don't want low dilantin troughs. I've seen people have therapeutic peaks and non therapeutic troughs, so I consider both quite important. A doctor explained to me the importance of a trough a few years ago, I was a new nurse and I didn't fully understand the numbers I'd see, so it helped me see things a little differently. Hope this helped!! :)