Companies such as Pfizer are introducing customer loyalty schemes for their big sellers.

Loyalty schemes that have proved successful for products such as airline tickets and dog food are now being adopted by pharmaceutical companies to retain market share.

In April, Pfizer launched its 'Viagra Value Card' programme in the United States, offering a free seventh prescription to men who buy six. With vardenafil (Levitra; Bayer/GlaxoSmithKline) and tadalafil (Cialis; Lilly) providing the first competition to sildenafil since its launch six years ago, the Viagra loyalty programme could help reverse a trend which has seen market share of new prescriptions fall from almost 80% to 65%.

But Daniel Watts, a spokesman for Pfizer, denies that the programme is a response to competitors, saying, “We're always looking for ways to communicate our messages and this way demonstrates leadership and rewards loyalty.”

Such loyalty schemes are seen as a way to drive repeat business and lock customers into a brand, who will then recommend business to their colleagues and friends by word of mouth, a process known as viral marketing. For example, Air Miles was launched in the United Kingdom in 1988 as a means of helping British Airways dispose of unsold seats. Now, 100 partner companies issue Air Miles to more than six million collectors.

Wally Olins, international corporate identity guru and author of On Brand, in which he argues that successful companies share 'seduction' ability — otherwise known as marketing — says of Pfizer's loyalty scheme, “It's a very good and obvious idea. It's been done with dog food for years — buy six dollops get one free, why not Viagra?”

Is it a response to market forces? Olins says it might well be, adding, “It's marketing spiel to say otherwise.” He says that reducing price could be the next step, a view elaborated by international marketing strategist Matthew Driver. “Such initiatives are clearly focused on market entrants. Sales promotions that drive volume put pressure on competitors as manufacturers can bump up production and reap the benefits of economies of scale, which could in turn be passed on as reduced price to consumers.”

Loyalty schemes have been slow to reach the drug market because of ethical concerns. But Driver says, “There would be 'no go' areas such as drugs that were additive or potentially hazardous with extended use, but for reliable drugs with lifestyle impacts such approaches are good business practice.”

An alternative incentive scheme recently launched by Novartis for antihypertensives has attracted US government backing. Through 'Take Action for Healthy Blood Pressure', Novartis offers a free 30-day trial of valsartan (Diovan), valsartan/hydrochlorothiazide (Diovan HCL) or amlodipine/benazepril hydrochloride (Lotrel), with a money-back guarantee for up to four months costs if, at the highest recommended dose, patients do not achieve their target blood pressure. They also get a free monitor and no-strings-attached hypertension information.

The American Nurses Association and Society of Hypertension broadly back the scheme. Barbara Alving, acting Director of the National Heart, Lung and Blood Institute said: “If this really gets the attention of those who otherwise would not have tried to have their blood pressure under control, then it's worthwhile. We have to look at it and say 'what is the greater good to be obtained here?'”

However, Jerry Avorn of Harvard University's Brigham and Women's Hospital says this is “a goofy idea [which] pushes therapy in a direction that is counter to what a lot of current research suggests is appropriate.” Critics such as Avorn say that $1.2 billion would be saved in the US if doctors followed current guidelines for prescribing cheaper antihypertensives such as diuretics.

But product guarantees reassure customers about efficacy, says Driver, and they seem to work. One example reported in the news illustrates how this could be true. A 61-year-old man with diabetes was previously reluctant to control his blood pressure of 155/75, but was apparently persuaded by the guarantee, saying, “They must be pretty sure of their product.”