New field offers better guiding for drug dosages

DEAR DR. ROACH: Do you have any information on cytochrome P450 testing for drug sensitivity?

ANSWER: Cytochrome P450 is a family of enzymes that are important for cell metabolism and critical for detoxifying many drugs.

Any given person has a particular set of P450 enzymes, and understanding them sometimes can help determine the correct exact drug dosages.

In a few cases, people with certain P450 enzymes cannot safely take some drugs.

However, the clinical usefulness of P450 testing is currently limited, and there are only a handful of drugs for which testing is recommended (for those who want to see the full current list, it’s available on the Food and Drug Administration website at tinyurl.com/P450drugs).

The majority of the drugs for which P450 testing is recommended are for HIV or cancer treatment.

Physicians prescribing these drugs would order the appropriate testing.

I do think that this field, called pharmacogenomics, is going to become increasingly useful, and it is likely that it will be used to more precisely guide drug choices and dosages.

DEAR DR. ROACH: My husband bought a used car about two years ago, and every time I ride in his car — no matter the time of day or where we are going — about 10 minutes into the ride, I begin to yawn uncontrollably.

These are deep, shuddering yawns that border on painful. Soon thereafter, my nose begins to run, my eyes water and my throat becomes scratchy.

Allergies seem the obvious answer, but I have a lot of allergies that don’t cause yawning. The yawns are very uncomfortable!

Do you have any advice, other than taking my car all the time? I will note that none of my other family members react this way.

ANSWER: Well, before today, I’d never heard of yawning being a sign of allergies. Yawns are common with fatigue or poor sleep, where air quality is poor and, in at least one spectacular case I heard of, from excess nervousness.

However, the runny nose and watery eyes are very consistent with allergies. I was able to find other case reports of people having yawns as an initial symptom of allergies.

If avoiding the offending agent (i.e., whatever is in the car) isn’t possible, pre-medicating with an antihistamine or prescription medication may be of benefit. DEAR DR. ROACH: I have a few friends who have needed chemotherapy for different cancers, and some of them talk about interest in the Gerson diet. I have seen some information saying it works and some saying it doesn’t; I’m not sure which is valid.

Can you help me understand what it is, and if there is any evidence on whether it can cure cancer, or if it is helpful in any way?

ANSWER: The Gerson therapy is a proposed treatment for cancer and other conditions.

It involves a special vegetarian diet, drinking many glasses of juice daily, enemas and numerous supplements.

The theory is that a high-potassium, low-sodium diet may have effectiveness for cancer treatment.

Unfortunately, there is no good evidence that the Gerson therapy is an effective treatment for cancer.

A well-done 2007 case series suggested that the positive psychological experiences in the patients treated with the Gerson therapy may provide some benefit.

Further, there is some good evidence that a vegetarian diet may help reduce progression of some cancers (such as prostate).

While I recommend strongly against the use of the Gerson therapy as a sole treatment for cancer, I think that traditional oncology treatment may benefit from paying attention to a cancer patient’s diet, in addition to his or her psychological and physical well-being.

It seems to me possible to use some “alternative treatments” for cancer along with, and with the explicit knowledge of and approval by, the person’s cancer specialist.

I found a useful reference on alternative treatments for cancer at www.camcancer.org/.

Readers may email questions to ToYourGoodHealth@med.cornell.edu .