Despite the huge potential market, big pharma is yet to find a good drug for weight loss. Consequently, the problem for drug companies is how to poke fat profits out of the disappointing drugs they have found.

Consider Xenical from Roche. Xenical is approved for use only by the obese and overweight people with related problems like diabetes. There is a much larger potential market of healthy people, like me, who want to be slimmer out of vanity. There is also a small but worrying group: teenagers and young adults with anorexia nervosa.

Xenical works by making you sick. It interferes with intestinal fat absorption so if you eat fat you suffer in your jocks. Patients are advised: “it’s probably a smart idea to wear dark pants, and bring a change of clothes with you to work.” These adverse effects remind people to stick to a low fat diet. Some people lose a lot of weight whilst persevering with Xenical but are probably the ones who would have done well with diet alone. For many people the extra weight loss is too small to be noticeable and mostly reverses after stopping the drug. There are suspicions about cancer from long term use but we don’t know either way.

Roche launched Xenical in Australia with ads on TV and in women’s magazines persuading people to ask their doctors for a prescription. Naming prescription drugs in advertising is illegal in Australia (except on the internet under the US Free Trade Agreement). Roche got around that by replacing the name Xenical with a green rectangle. They provided a phone service to encourage patients to keep taking the drug. This service used counselors with a conflict of interest discussing the pros and cons of a drug that was paying for their wages.

Sales were too thin for Roche’s tastes so the company found a way around the ban on naming prescription drugs in advertising. They lobbied successfully for Xenical to be re-classified as available without a prescription. Then they plugged the drug heavily on TV including during Australian Idol (remember those worrying teenagers and young adults I mentioned earlier?)

The consumer association Choice sent a 19-year-old woman of healthy weight to 30 pharmacies of which 24 sold her Xenical despite their professional obligation to refuse. Choice complained to the regulators who banned further ads naming Xenical. Roche appealed and lost last week. The company is now considering giving up advertising their drug. It has been a fascinating game of fat and mouth – sorry – cat and mouse. If Xenical is starved of advertising it may just fade away.