This is true,your doc should confirm this,and keep the doc informed of how you feel if you are having unfavorable reactions.
Med doses are based on weight range(s),even in veterinary field.
They are established in the experimental stage,thus creating recommended dosages,then other factors are considered,leaving space for tweaking.
When being created and in clinical trials,every med has to have an administered dose based on weight range, could you imagine what would happen otherwise?
Do you know in the experimental stage dose ranges are established using lab rats,canines,rabbits,lab monkeys,porcines,etc. (sad reality) in developing what can be therapeutic dose or lethal dose,besides the formulation/chemicals,side effects. But almost with everyone, medication OTC or prescription has dosages,which at one time weight range was factored in determining recommended dosages.
Best to always take questions up with the prescribing physician when using a med or topical product they have prescribed. If changes are to be made,adjusting dosages or time of taking them,it should be determined and recommended by the doctor.
No one can't, and should not go by what we share here,or find on the internet,even though hearing other's experiences and reading the drug websites, can be interesting, never use that for a substitute.
Contact your doc.
Take care,
DE