Cmax Tmax

Cmax = C [drug]max in BLOOD.
Cmax is a beautiful concept to understand. For ex., as an RN, you know the peak time of Humalog/Novolog is about 1.5hr-2hr. This means this would leave the pt most at risk for hypoglycemia 1.5-2hr after insulin administration. Therefore, if suspecting or worrying, you should check the patient 1.5-2hr for blood sugar after insulin adminstration time. When was an RN student (like a long time ago), it always bewildered me why for humalog/novolog which lasts for like 4-6hrs but pt is most at risk at 1.5-2hrs afterwards. It turns out that is when the drug is available most in the blood and therefore working very hard to get blood sugar down. Therefore, it's best to check the BS 1-2hrs after BS administration rather than later due to Cmax.

However, Cmax Tmax Useful for IV meds and meds absorbed well. Cmax and Tmax kinda useful for insulin. But insulin is quite different in real life. SubQ Lantus 4 units => lasts about a whole day, not half life or short life. Extended release dose more like that.

Extended-release pills (similarly to Lantus subQ)=> cannot really calculate Cmax or Tmax.

Ex: 20mg Amlodipine to 80y/o pt (if you're idiot enuf to do it!) & pt is naive to this = >u wanna check at Cmax

P.s.: Learning pharmacology makes it fun to read the monographs for drugs! You can understand more.


References for Insulin Tmax:
http://www.drugs.com/ppa/insulin-analogs.html
http://pi.lilly.com/us/humalog-pen-pi.pdf
http://www.rxmed.com/b.main/b2.pharmaceutical/b2.1.monographs/CPS-%20Monographs/CPS-%20(General%20Monographs-%20H)/HUMALOG.html
http://www.accessdata.fda.gov/drugsatfda_docs/nda/99/21017_Humalog_biopharmr.pdf

~Miss Student