From the January 29, 2009 issue
Problem: A female patient with primary pulmonary arterial hypertension (PAH) who was receiving TRACLEER (bosentan) and REVATIO (sildenafil) went to the emergency department (ED) with ischemic chest pain and ECG changes. The ED physician reviewed the woman’s medication list but did not know that Revatio was sildenafil or understand its contraindications. The patient was given aspirin and nitroglycerin sublingually and later was started on an IV nitroglycerin infusion for continued chest pain and elevated troponin-T.
The use of organic nitrates in any form, at any time, while a patient is taking sildenafil is contraindicated. This contraindication is echoed in product monographs for other selective phosphodiesterase-5 inhibitor drugs such as CIALIS (tadalafil) and LEVITRA (vardenafil). Thankfully, in this case, which was reported recently by our sister organization in Canada (ISMP Canada Safety Bulletin January 13, 2009), the patient experienced no adverse effects or blood pressure changes because an internist soon recognized the problem and stopped the infusion.
Sildenafil is probably better known as VIAGRA, a drug approved for the treatment of erectile dysfunction. When used for this indication, sildenafil is typically prescribed in 50 mg doses to be taken 1-4 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, including mention of associated contraindications. Although dosing differs, if the patient’s sildanafil had been prescribed and communicated under the Viagra name, perhaps the ED physician would have recognized the problem with prescribing nitroglycerin. However, Revatio has the approved indication for treatment of PAH (to improve exercise ability); Viagra does not. In most cases, FDA would not approve a new brand name just because the drug has a new indication. But because of the stigma PAH patients might associate with taking Viagra, FDA approved Revatio as the new brand name.
As with the doctor in the case above, most physicians are not experts on the management of severe PAH, nor would they 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—such as Viagra—before the new product is launched. Further, patients with PAH frequently have concomitant coronary artery disease, increasing the risk of receiving a nitrate.
In the past, patients have taken the same medication prescribed or dispensed under more than one trademark. For example, in our June 2, 2002 issue, we mentioned errors with ZYBAN and WELLBUTRIN (both buPROPion), PROPECIA and PROSCAR (both finasteride), and SARAFEM and PROZAC (both FLUoxetine). In that article, we pointed out that duplicate therapy may 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 physician prescribes the product by its generic name while it is dispensed and labeled by its brand name (e.g., COUMADIN or JANTOVEN for a patient already taking warfarin).
Safe Practice Recommendations: FDA often requires companies to analyze whether a dual brand name or two different brand names would be safest for a product marketed for two very different indications. If dual brand names are used, manufacturers could perform an important service by clearly warning patients and health professionals on the package label, if space is available, and the package insert that the drug is available under both names.
Health professionals can also reduce the risk of errors by conducting a thorough drug history and reviewing drug information if they encounter unfamiliar product names. To help patients avoid taking the same product under different names, health professionals should encourage them to fill their prescriptions at the same pharmacy when possible. The insurance adjudication process normally identifies duplicate therapy, but in an era of $4 generics, not all prescriptions are processed in this manner. Patients with PAH who take Revatio should be encouraged to note on their medication list that the drug is also marketed as Viagra.