My doctor gave me a prescription for Vicodin for pain control for my chronic back pain. I found that taking one pill just didn’t cut the pain, so I upped the dose to two pills. That worked great but it meant I ran out of the drug in half the time. Now the pharmacist won’t refill the prescription. What can I do?

Give your physician a call and explain what happened. It is known that some people require 10 to 40 times the standard dose to get the same effect. This difference in response to drugs has also been observed in animals, so we know it isn’t just a psychologic problem.

With any of the narcotic pain relievers, there is always a concern about addiction. But scientists have discovered that the need for a higher dose may be based on your genetic makeup. Research has uncovered a handful of these potential differences. It’s expected that there may be hundreds of genetic variations like this.

For example, some folks don’t have the CYP2D6 enzyme needed to activate the drug. Without this enzyme, the drug isn’t metabolized (broken down) and the patient gets no (or very minimal) pain relief. Another problem occurs when P-glycoprotein doesn’t function properly. This is the protein that transports the opioid across cell membranes. Without normal P-glycoprotein, there can be too little or too much opioid in the cells.

Here’s one more example of genetic mutations that affect how opioids work in the human body. When the COMT gene is mutated, it no longer makes the enzymes that break down neurotransmitters that carry chemicals around the body. Without proper COMT, the cell receptor sites for opioid are also affected.

These examples are really only the tip of the iceberg. The more scientists explore this direction of research, the more differences in genetic makeup are discovered. The cell receptor sites just mentioned? It turns out there are probably many different types of pain receptor sites — a change in any of these can affect how well opioids attach to the cell, transfer across the cell membrane, and have the intended effect to reduce pain messages.

Genetics isn’t the only factor in how people respond to opioids. There is still a significant effect of personality and psychology — some people tend to lean toward suffering rather than overcoming. And the source of the pain can also contribute to how well opioids work.

Your physician is the best one to evaluate all of these factors and determine what’s best for you. The information you give him or her about dose effectiveness will help. The pharmacist cannot refill a prescription for opioids early without your physician’s approval.