How is the half-life of a medicine designed to have a short half-life or a longer half-life?
For example, CONCERTA’s half-life is 3.5 hours, and another med, for instance, Trintellix – Vortioxetine, has a longer half-life of 66 hours.
In: Chemistry
Typically the half life is actually the opposite. It’s not designed to be a certain length of time.
That just happens to be how fast your liver or kidneys or other organs can process and break down that medication. The half life time wasn’t designed in a laboratory, it was discovered when they were testing different dosages of the medication in different people during the trials.
Now, they can do some thing to make medication “last longer” In The body, the most common being “delayed release” medications where they design the pill or capsule to take longer to dissolve in the stomach than a normal pill, meaning if you’re taking a 100 mg pill, instead of all 100 mg entering your blood at the same time, it gradually enters the blood over a longer period of time.
The other commenter isn’t completely correct, at least with modern techniques – optimisation of the drug during its development can involve altering its structure to (typically) increase its half-life.
For some drugs, you can make it more lipophilic by changing out atoms – for instance, swapping out hydrogen for fluorine. This means it binds better to tissues, so it isn’t as easily flushed away by the kidneys or broken down in the liver. [Source](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6004573/)
For large protein biologics used as medicine, if you make them large enough they won’t be removed by the kidneys. You can also add polyethylene glycol which makes them more immune tolerant so they aren’t removed that way, or by adding human serum albumin, which makes them more resistant to being broken down by enzymes called proteases, as well as being a big molecule that isn’t removed by the kidneys as easily. [Source](https://www.sciencedirect.com/science/article/pii/S0753332219301623)
To add serum albumin you can add lipids (long molecular chains) to the drugs (such as insulin) so that they “stick” to the albumin in your body once the drugs are taken in and absorbed. [Source](https://pubs.acs.org/doi/10.1021/acsmedchemlett.8b00226#)
Hope this helps!
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