Medication dosage?

Question

Many of the popular drugs these days seem to come in just a few increments. Usually no more than say 5. Zoloft, for instance, comes only as 25mg, 50mg, and 100mg. Advair comes even in just two; 100/50 and 250/50.

Why are these medications not calculated and prescribed according to individual patient needs, such as weight, age, gender etc. as some of the other meds are (like Lidocaine)?

I understand that a mayority of the people taking these medications thoroughly benefits from them as they're prescribed today, but could the outcome improved (especially for individuals who do not respond well) by "tailoring" the dosage to the patient?

Answer 1

Actually I think advair also comes in 500/50, unless they removed it. Some medications are calculated according to weight. When I started on zoloft I was put on the lowest dose, to avoid adverse reaction. Also, for infections I think the dose is determined by how strong the infection is and the patients size.

Answer 2

Some medications have a narrow therapeutic index and more detailed control of input is needed.

Then there are other meds that have a therapeutic effect over wide plasma ranges with little worry of dangerous side effect to people on the high end of the normal range.

It very well may be the case that those SSRI like zoloft and prozac should have their plasma levels monitored, but they are not even though the elimination rates can vary greatly and the drugs are know in some cases to lead to suicide or violence.

They never try to take plasma or brain levels in dead people who become violent while on these drugs and compare it to other people who die of natural causes also on the meds.

It is a gaping whole in our understanding.

Dosage adjustments do not always have to be with regard to the magnitude of the dose, it also can be manipulated with regard to frequency of dosing (for slowly eliminated drugs).