Rx. Drugs, Pharmacology, and Side Effects Part I

I think it is important for the public to understand how and why drugs are used, the studies that are used to test for efficacy and side effects, and the importance of using drugs properly.

For starters, it is not true that the less of a drug you take, the less sick you are. Rather, since using any drug exposes you to its side-effects, which often are NOT dose-dependent, you should always take enough of the drug to get the maximum benefit, rather than see how little of the drug you can get away with. You certainly should not be like some of my patients who skip asthma inhalers to see if they really "need" it. In fact, if I suspect exercised-induced asthma in a patient, rather than going through pulmonary function tests with methacholine challenge, I would prefer to convince the patient that the inhaler is needed. So I ask the patient to use an anti-inflammatory inhaler one-half hour before heavy exercise every other time for the next 20 exercise sessions, and then ask the patient if he/she noticed an increase in stamina or time to fatigue/dyspnea. In this way the patient sees the need for the inhaler.

Treating high blood pressure is more of a challenge, because a patient (usually) cannot feel high blood pressure. However, after I tell them that the one event treating hypertension has been shown to prevent is a stroke, they all become faithful converts. Most patients seem to fear loss of function more than death or cancer.

Now how does the FDA require that drugs be tested? In the old days, human prisoners were used as guinea pigs, with time off their sentence used as an inducement to participate. Then it was decided that this was immoral, so now we first test on animals, such as white lab rats and guinea pigs, and we first look to see (a) if any organs are damaged (usually the liver), or (b) if tumors/cancers are induced. The problem, of course, is that all animals have different physiology and biochemistry than do humans. For instance only the guinea pig, along with humans, needs exogenous Vitamin C. All other mammals have the enzyme necessary to make Vitamin C. So already the internal milieu will be different. Then we try to figure out, experimentally, the LD50, i.e. the dose (mg/kg) that will kill half the experimental animals. Then we will try massive doses of the drug to make sure that the drug is not carcinogenic to animals. Of course, an increased dose for a short period of time is not physiologically equivalent to a lower dose over a longer period of time, but that is what we do. One problem with massive doses is the pure effect of a large dose: 8 glasses of water a day is fine for humans, but 80 glasses of water a day will quickly lead to death from dilutional hyponatremia and secondary brain swelling.

Now we have to see if the drug works, so we test the drug against a placebo, and look for a positive effect. Of course, if we already have a treatment for the disease or condition in question, which we usually do, then we test the drug against a drug that we know "works". The drug company runs the test to see if their new drug is "not inferior" to the standard drug for the condition. Later on, when they want to corner the market, they will run a different comparison drug to show that their drug is superior to their competitor. Still later, once the FDA approves the drug for conditions specified in the PDR (e.g. beta-blockers for hypertension), the manufacturer will look for a unique "off-label" benefit, i.e. a use not specified in the PDR. This is neither illegal nor immoral. So now physicians will also use beta-blockers to prevent or reduce the incidence of migraine headaches, and also give beta-blockers (under most conditions) to survivors of heart attacks to lessen the chance of a second heart attack.

The FDA requires the drug company to list all observed side-effects in the PDR. The side effects can either have been observed, or included because of the class of drugs. Remember, if the drug company warns you about a possible side effect in the PDR, it is difficult for you to sue them if you get the side effect. Sometimes this is overdone, as in the case of steroid creams which have the same steroid warnings as to high-dose oral medicine. Later published studies may show that the theoretically predicted side effect does not occur, but unless the drug company wants to spend the money to submit new studies to the FDA, this result never appears in the PDR.

BTW, over-the-counter drugs have a much less stringent warning requirement, which is usually to call your doctor after several days or doses. Nowhere on any aspirin bottle, for instance, are you warned that if you have nasal polyps and asthma, a single dose of aspirin can kill you by causing severe allergic bronchospasm. Maybe that's why when Bayer first patented aspirin it was available by prescription only.

Now, what happens after the drug is released by the FDA to be available to the public through a doctor's Rx? All doctors are requested to report any unusual occurrences (lab tests, physical side effects, acute medical attacks) that occur to patients on the drug. The problem is that the drug initially was tested on naive patients, i.e. on patients on no other drug. But the typical patient in his/her sixties is usually on five to seven drugs (diabetes, hypertension, high cholesterol, GI reflux, etc.) so the new drug is added to the chemical mix, and now we have the patient undergoing a new drug test (i.e. 6 drugs plus the newbie) that has never been studied before, and there are certainly no published results dealing with this particular combination. So if the doctor reports an effect, it is initially impossible to know if the effect is due to the drug (if indeed i t is) or to the combination of the new drug with one of the other six. And no one, to my knowledge, when they file an incident report with the FDA include any information on any artificial sweeteners the patient may be ingesting, which is, of course, a 7th drug.

More to come in a later blog, but one caveat of which you may not be aware. NO governmental body tests, clears or approves any new surgical technique. So if a doctor can convince you to be the first patient in the world to undergo robotic prostate or heart surgery, so be it. And no one really tests new drugs on children or pregnant women, for obvious reasons. I personally feel that any parent who volunteers his/her child for any new drug test is guilty of child abuse!