Counterfeit versions of the erectile dysfunction treatment tadalafil (Cialis) have been found in the United Kingdom's legitimate supply chain. This is the first such occurrence since the discovery of fake versions of the ulcer drug ranitidine (Zantac), packaged as Azantac, in 1994.
The Medicines and Healthcare Products Regulatory Agency issued a drug alert last week informing healthcare professionals of two fake batches of Cialis (20 mg; lot numbers A031410 and A041410).
However, it is not known how many counterfeit tablets have entered the supply chain or how many patients have taken them, the agency said. But Lilly ICOS, the maker of Cialis, says the quantities are believed to be small. For legal reasons the manufacturers and distributors of the fake products are not being named, as the matter is being followed up by the agency's enforcement arm.
The counterfeits were discovered after a patient complained about a “crumbling tablet” to Lilly ICOS. The company subsequently alerted the agency.
Unlike other counterfeits, which usually contain dangerous ingredients or no drug at all and are often found in developing countries, these tablets contained the active ingredient (tadalafil).
Although the agency says initial analytical tests of the products do not indicate an immediate risk to patients, their quality cannot be guaranteed. Patients have been told to return the products to their pharmacy, and Lilly ICOS has set up a free advice line. Patients are being told that the products “may not work” or “may give an abnormally prolonged and uncomfortable erection” and that medical advice should be sought.
Concerned that the news may affect the reputation of its product, Lilly ICOS stressed that “genuine Cialis is not affected by the matter.” Cialis was launched in the United Kingdom in early 2003 and has 19.5% of the market share for treatments for erectile dysfunction. Its largest competitor is sildenafil (Viagra), which is manufactured by Pfizer.
Dr Richard Barker, director general of the Association of the British Pharmaceutical Industry, said, “This incident highlights the need for the greatest vigilance and scrutiny, especially when medicines are introduced into the system other than from their original manufacturers. The best protection against counterfeiting is to ensure that the products bought are those supplied by the authentic manufacturer.”
Counterfeit drugs are a growing problem around the world, affect an estimated 5% to 7% of the pharmaceuticals market. However, in developing countries the activity is more pronounced—for example, in Nigeria and Pakistan counterfeit drugs make up 40% to 50% of the market. In February drug regulators held a conference on counterfeit drugs and discussed the possibility of introducing an international framework convention to tackle the problem (BMJ 2004;328:486).