I was just wondering what a half life of 16 hours means with a medication?

Does it mean the pill lasts for 16 hours?

"A medication's half-life is the time it takes for the plasma concentration of a drug to reach half of its original concentration. More simply put, the half-life of a drug is how long it takes for half of it to be eliminated from the bloodstream."

Like Fuu! said Half-Life is the amount of time it takes for half of the drug to be excreated from the system.

For example, if you take 100mg Zoloft which has a half life of 24 hours, after 24hours, there will be 50mg left in your system. If Zoloft's half life had ben 12 hours, after 24 hours there would only be 25mg left in your body (due to 2 half-lifes).

Cool. Thanks for clearing that up for me guys.