Risks of online ED drugs exposed

Buying potentially counterfeit drugs for erectile dysfunction (ED) over the Internet may bring you much more than sexual disappointment. It could also expose you to hazardous or even fatal ingredients while leaving conditions such as diabetes or high blood pressure undiagnosed, a new study warns. 

A research team from the UK, Sweden and Pfizer in the US reviewed more than 50 studies published between 1995 and 2009 to determine the scale of counterfeiting for phosphodioesterase type 5 (PDE5) inhibitors such as Pfizer's Viagra (sildenafil), as well as the associated direct and indirect risks to health. Their findings were published online in the International Journal of Clinical Practice (IJCP).

As an illustration of just how much risk is involved, the authors point to a recent report in the New England Journal of Medicine chronicling an outbreak of hypoglycaemia in Singapore. The diabetes treatment glyburide was subsequently found in counterfeit tadalafil (Eli Lilly's Cialis) and herbal preparations used to treat erectile dysfunction. Of the 150 non-diabetic patients admitted to hospitals, seven were comatose as a result of severe neuroglycopenia and four eventually died.

Seizures by law enforcement officers indicate that PDE5 inhibitors are the most commonly counterfeited class of drug in Europe, with 35.8 million sildenafil tablets alone intercepted between 2004 and 2008, the IJCP article notes. An estimated 0.6-2.5 million men in Europe could be exposed to illicit sildenafil. As a point of comparison, the authors add, IMS Health estimates the number of people taking legal sildenafil in the EU at 2.5 million in 2006.

Analyses by Pfizer of suspected counterfeit Viagra found that only 10.1 per cent of samples labelled 'Viagra 100mg' were within 10 per cent of the advertised tablet strength. Substitute ingredients identified in fake sildenafil tablets have included amphetamine, caffeine, talcum powder, paints, printer ink, paracetamol, the antibiotics metronidazole and chloramphenicol, and the antidepressant fluoxetine, along with large quantities of unidentified impurities.

There are also 'herbal' or 'dietary' supplements marketed for sexual dysfunction, which consumers may believe to be harmless, the authors point out. Analyses of these have identified the presence of PDE5is or related compounds including sildenafil, tadalafil, vardenafil, hydroxyhomosildenafil, thiosildenafil and thiomethisosildenafil. 

Among the direct risks of taking products or ED that may contain unknown pharmaceutically active ingredients and/or impurities are serious adverse events or even death, accidental overdose through mislabelling or drug-drug interactions, the researchers warn. Moreover, since inert ingredients provide no treatment benefit, "patients remain untreated and may be discouraged from seeking additional help because they believe that medication does not work for them."

The indirect risks include unsupervised use of PDE5 inhibitors by men who may have common co-morbidities such as hypertension, dyslipidaemia and diabetes, and may hence miss the opportunity to address these through conventional medical channels, the authors say.

In a broader sense, using drugs "that are not what they are supposed to be provides no basis for determining drug efficacy or providing guidance for future use."

Internet threat

The IJCP article also looks at the close association between the Internet and counterfeit PDE5 inhibitors, together with the trend for risky behaviour in this context. In Europe, for example, the Experts on the Operation of European Conventions in the Penal Field have estimated that 44 per cent of sildenafil sold over the Internet is counterfeit. Between 4,500 and 15,000 websites sell PDE5 inhibitors and other treatments for ED, although other estimates put this number at 500,000.

The article goes on to cite findings from the European Alliance for Access to Safe Medicines and Pfizer itself that highlight the unreliability of online pharmacies and the drugs purchased from them, as well as the strong tendency for men to buy ED drugs without a prescription via the internet.

One Internet-based observational analysis of the sources used by men in the UK, Germany and France to obtain PDE5 inhibitors revealed that 30.6 per cent of participants had no interaction with the conventional healthcare system. In a larger follow-up study conducted in the UK, Germany and Italy, 10.5 per cent of nearly 12,000 men reported using PDE5 inhibitors in the previous six months and 32.3 per cent of these obtained the drugs without healthcare professional (HCP) interaction.

More than 60 per cent of the men who bypassed HCP interaction in buying a PDE5 inhibitor believed they would get the same prescription-only medication via the internet as through conventional sources, the authors note. And the majority of men were not concerned about the efficacy of medicines ordered via the internet, although most generally felt that drugs sold through the internet were less safe than those prescribed by a doctor.

The IJCP article also addresses some of the legal loopholes or anomalies that may facilitate trade in counterfeit drugs, as well as the strong profit motive. While proper international co-ordination is "absolutely essential" in this field, "many countries lack the resources and⁄or political willpower to prioritise an anti-counterfeiting agenda," the authors comment. Diplomatic obstacles and varying legislation are further hindrances to co-ordinated action.

A specific problem with ED drug counterfeiting is that "the threat of Internet-associated purchase of PDE5is is not fully recognised," they add. While awareness-raising campaigns organised by governments and industry have already been rolled out, doctors who treat ED "should inform patients of the dangers of ordering PDE5 inhibitors via the Internet as part of a multi-pronged strategy to combat counterfeiting," the researchers say.

The three of four researchers for the IJCP article not employed by Pfizer, including lead author Dr Graham Jackson of London Bridge Hospital in the UK, are or have been consultants for Pfizer among other pharmaceutical companies.