# What factors affect the time taken for a drug to reach steady-state?

42
Hi all,

To be more specific, do the following factors increase the time taken for a drug to reach steady-state?

Increased frequency of drug administration

Increased dosage of drug administration

If not, please explain why that is the case.

Many thanks,
Jay

Last edited: Jul 10, 2013

### Staff: Mentor

Do you mean increase the time or decrease the time? Your question seems backward to me...

Last edited: Jul 10, 2013
3. ### DiracPool

813
Of course, both of them do. Why would you think they wouldn't? The factor you forgot to mention, however, is the specific elimination half-life of the drug in question, that is also principally important as to when drug intake reaches a steady state, and varies with the drug in question.

Last edited: Jul 10, 2013
4. ### SW VandeCarr

There are many things that affect the steady state plasma concentrations for a given drug. Both the size of the individual dose and the number of doses taken per day are important and you can't say a priori which is more important. The plasma concentration at steady state is dose dependent but the time to steady state is dependent on the elimination half life.

The link below is essentially a mini-course in pharmacokinetics. It contains some very simple differential equations so I think a basic knowledge of calculus, if that, is all you need to follow the course.

http://www.pharmpress.com/files/docs/clinical_pharmacokinetics_samplechapter.pdf

It also contains some case studies which may or not interest you. They are not essential to understanding such concepts as elimination half life, volume of distribution, one and two compartment models, etc.

Last edited: Jul 11, 2013
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