Why does the chronic administration of some drugs require increases in dosage?

Question

to achieve the same effect or decreases to avoid toxicity?

Answer 1

According to my revision notes:

"The effects of a drug decrease rapidly upon readministration ("self antagonism", "desensitisation" or "tachyphylaxis"), and can be because of:
1. Change in receptors
2. Loss of receptors
3. Exhaustion of mediators
4. Physiological adaptation
5. Increased active extrusion"

Word for word that is, copied from my notes!

Hope this helps

Ashley

Answer 2

The body develops a tolerance to some drugs, so it takes more to work correctly