Understanding Drug Tolerance and Resistance

When people use certain medicines for a long time, they might notice that the medicines don't work as well as before. This can happen for a few reasons:

1. How the Body Behaves with Drugs:

   • Sometimes, the body changes how it processes drugs. This means that the medicine might not work as well, reducing its effects by about 50%.
   • The way the body absorbs, moves, and gets rid of the drug can change, which can affect how much of the medicine is actually in the blood.

2. How Cells Respond to Drugs:

   • Over time, the cells in our body can stop responding to drugs as effectively. For example, with long-term use of opioids, there can be up to 90% less response from receptors that the drugs target.
   • The pathways that transmit signals in the body can also change. This means that even if the same amount of medicine is taken, the effects might not be as strong.

3. Changes at the Cellular Level:

   • Cells might become better at pushing the drugs out. This is known as enhanced efflux pump activity, which can lead to a 50-100% reduction in how much drug stays in the cells.
   • Sometimes, changes in the cell’s DNA can make it harder for the drug to work. This is seen in some tumor cells, where more than half can become resistant to certain cancer treatments.

Learning about these changes is important. It helps doctors find the best ways to treat patients and improve health outcomes.