Recently, I was reminded how important it is not to believe or act upon unverified warnings. Before going to my clinic, I received an e-mail from a colleague advising me to clean my computer due to a dangerous virus that was impenetrable to virus scans and spreads through address books. This turned out to be a bogus warning. Two hours later, a PNP colleague shared that her patient was warned against ever immunizing her children because "the immunizations are made from aborted fetuses".
Set the Record Straight
In this era of rapid information dissemination, numerous "facts" are misstated, misquoted, or exaggerated. The need to adopt a skeptical thinking pattern is critical in our Internet-saturated culture. Fortunately, some excellent sources can help set the facts straight. For checking out the many rumors related to pharmaceutical products and for unbiased evidence and advice on new developments in drug therapy, I have found Prescriber's Letter (http://www.prescribersletter.com) to be very useful.
Common Rumors
Here are some common rumors clinicians have reported to Prescriber's Letter, with a short summary of how their editors have attempted to set the record straight:
Rumor: Magnesium is needed for calcium absorption. Truth: There is no proof that the magnesium/calcium combo is any more effective for preventing bone loss or that calcium absorption is increased with magnesium.
Rumor: All antibiotics reduce the effectiveness of contraceptives. Truth: This rumor started over 30 years ago with rifampin and griseofulvin. Oral contraceptive levels are not decreased by tetracycline, doxycycline, ampicillin, quinolones, or metronidazole. In fact, oral contraceptive levels are actually increased by erythromycin, clarithromycin, and trimethoprim-sulfamethoxazole. Very few women might have genetic metabolic variations, so clinicians should tell women to use a backup contraception during their course of antibiotics plus 7 days after.
Rumor: Floating an asthma inhaler in water tells if it's empty. Truth: This idea dates back to when the asthma propellant was a fluorocarbon with a specific gravity of 1.4. Newer products are propelled by hydrocarbons with a specific gravity of approximately 0.9. Therefore, this method no longer works, and results vary whether the stem is up or down. In addition, some new products float when the canister is full. Counsel patients to either keep track of the number of puffs they have used or (if appropriate for the product) use a counter device.
Rumor: It's okay to take drugs that interact with grapefruit, as long as they are separated by 2 hours. Truth: Grapefruit can alter the levels of many drugs (e.g. lovastatin, simvastatin, diazepam, some calcium channel blockers, protease inhibitors), and it can take 3 days or longer for the enzyme activity to recover. Evidence also states that tangelos, limes, and Seville oranges have the same effect as grapefruit, and that 8 ounces is enough to alter drug levels.
Rumor: The active ingredients difference between generic and brand drugs is 20%. Truth: Generics are FDA-approved if the average rate of absorption is within 80% to 125% of the brand product. The actual difference (when including the confidence interval around the mean) is closer to 3.5% for most products.
What about the rumor that vaccines are made from aborted fetuses? The truth is that human diploid cells were originally developed in the 1960s from the lung tissue of two aborted fetuses. Since then, scientists have used these same cell lines to culture inactivated viruses for rubella, hepatitis A, varicella, and rabies, and will use them for future generations of lab cultures and vaccine research. No new cells have been added to the original cell lines in the past 40 years. Do you have a rumor to dispell?
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