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Multiple Brand Names for the Same Generic Drug Can Cause Confusion
A female patient with primary pulmonary arterial hypertension (PAH) who had been taking Actelion’s Tracleer (bosentan) and Pfizer’s Revatio (sildenafil citrate) arrived in the emergency department (ED) with ischemic chest pain and electrocardiographic changes. The ED physician reviewed the patient’s medication list but did not recognize that Revatio was the same drug as sildenafil and was unaware of its contraindications. The patient received aspirin and nitroglycerin sublingually and later was started on an intravenous nitroglycerin infusion for continued chest pain and elevated troponin-T levels.
Sildenafil is more commonly known as Viagra, which is approved for the treatment of men with erectile dysfunction. When used for this indication, sildenafil is typically prescribed in 50-mg doses to be taken 1 to 4 hours before sexual activity. When used to treat PAH, sildenafil is typically prescribed in 20-mg doses to be taken three times daily.
As Viagra, sildenafil has received widespread professional and direct-to-consumer advertising that mentions contraindications. Although the drug’s dosage differs for the various indications, if sildenafil had been prescribed and identified as Viagra, perhaps the ED physician might have recognized that simultaneously prescribing nitroglycerin would cause a problem. Revatio has the approved indication for the treatment of PAH to improve exercise ability; Viagra does not. The FDA does not usually approve a new brand name just because a drug has a new indication; however, because of the stigma that patients with PAH might associate with taking Viagra, Revatio was approved as a new brand name for sildenafil.
Some physicians who care for patients with severe PAH might not recognize that Revatio is the same drug as Viagra. Dual trademarks for a single product are particularly problematic when one of the product names is well established before the new product is launched. Further, patients with PAH frequently have concomitant coronary artery disease, increasing the chances that a nitrate will be prescribed for them. However, a life-threatening drop in blood pressure can result if nitroglycerin is taken with a medication for erectile dysfunction.
In the past, patients have taken the same drug prescribed or dispensed under more than one trademark. For example, my column in the May 2006 issue of P&T mentioned errors with Zyban and Wellbutrin (both bupropion, GlaxoSmith-Kline), Propecia and Proscar (both finasteride, Merck), and Sarafem and Prozac (both fluoxetine, Eli Lilly).1 It was pointed out that duplicated therapy can occur when branded generic products are available from different manufacturers; when the same drug is dispensed from two pharmacies under two different brand names; or when a product is prescribed by its generic name while it is dispensed and labeled by its brand name—for example, Coumadin (Bristol-Myers Squibb) or Jantoven (Upsher-Smith) for a patient who is already taking warfarin.
Clinicians can also reduce the risk of errors by obtaining a history of all drugs taken by the patient and by reviewing all available information about a specific drug if they encounter unfamiliar product names. To help patients avoid taking the same drug under different names, clinicians should encourage patients to fill all of their prescriptions at the same pharmacy. The insurance-adjudication process normally identifies duplicated therapy, but in an era of $4 generic drugs, not all prescriptions are handled in this manner.
For instance, in the outpatient or community pharmacy, when the pharmacist enters a prescription into the computer system but before a label is printed, the prescription information is sent to the insurance company for approval (i.e., adjudication). The company can deny prescriptions for many reasons, including the fact that the patient had a similar script filled (e.g., the same generic drug name). When a pharmacy offers generic drugs for only $4, it means (behind the scenes) that the pharmacy does not send the information to the insurance company if the patient is paying only $4 in cash. Therefore, if a pharmacy offers $4 generics, the double-check process (in which the insurance company could reject the prescription because the patient is using something similar) does not take place.
Patients with PAH who take Revatio should be encouraged to note on their medication list that the drug is also sold as Viagra.