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May 1998

L.D. DeSimone
Chairman of the Board and Chief Executive Officer, 3M
3M Center,
St. Paul MN 55144-1000
USA

re: the promotion of Duromine (phentermine)

Dear Mr DeSimone,

A fellow health professional has asked MaLAM¹ to write to you about the marketing of Duromine in Australia and sent us your 1998 advertisement with the following claims:

"Duromine. Individually tailored obesity management

Proven efficacy in general practice.

A safety profile you have come to trust."

Comparison of your claims with initial conclusions based on the scientific literature available to MaLAM, summarised below, raises some questions. This letter is intended to give you the opportunity to express your point of view so that we can assess whether those claims assist appropriate therapy. We hope that you will either provide evidence to support your claims or reconsider the promotion of Duromine. We are optimistic that dialogue can lead to improvements in pharmaceutical promotion to the benefit of the public, health professionals and your company.²

Initial conclusions from the scientific literature.

Efficacy

The approved indication for Duromine in Australia is: "In the management of obesity as a short-term adjunct in a regimen of weight reduction based on kilojoule restriction." A range of therapies - behavioural changes, diets and drugs - are capable of achieving weight reduction in the short-term. The key is being able to show that the weight loss is retained in the long-term. MaLAM is unaware of any studies that show that short-term use of Duromine leads to permanent weight loss.

The United States National Task Force on the Prevention and Treatment of Obesity recently published a systematic review of the long-term pharmacotherapy of obesity.³ It identified only one trial involving phentermine that lasted longer than 24 weeks. This is the 1968 trial by Munro et al that is cited in your advertisement.⁴ At 36 weeks there was a significant difference in weight loss between the phentermine and placebo groups. However, there was no follow up after treatment ceased. According to the U.S. Task Force when pharmacotherapy of any kind is stopped "Several months after discontinuation of medication, there was generally no difference in weight between the groups that previously received active drug and those that received placebo."

It is possible that long-term use of phentermine might be effective in weight reduction. It is also possible that the adverse effects of phentermine may lead to increases in morbidity and / or mortality. Use of phentermine may reduce the motivation required for long term changes to diet and exercise. Long term studies to determine these issues have not yet been done.

Safety

Phentermine has been associated with amphetamine-like adverse effects including precipitating angina, increasing blood pressure, anxiety, irritability, tachycardia, insomnia, restlessness, and also dry mouth and changed bowel habit.⁵

Your advertisement implies that long-term safety of phentermine has been established because it has been used for 30 years. In the absence of any systematic long-term safety evaluation MaLAM cannot accept this statement. To cite another example from the area of anti-obesity drugs, fenfluramine and dexfenfluramine were also used for many years and considered safe before cardiac valve abnormalities associated with their use were identified. High levels of serotonin may have caused these abnormalities. Many of the cases were taking fenfluramine in combination with phentermine. Phentermine may have contributed by reducing the uptake of serotonin by the lungs. A dangerous drug interaction between phentermine and SSRI antidepressants is possible but adequate studies to confirm or deny this have not yet been done.⁵

BMI

It is now generally accepted that a Body Mass Index (BMI) greater than 27 kg/m² be considered the minimum indication for treatment with drugs for patients without existing obesity-related comorbidities.³ Your advertisement promotes the use of Duromine for "obesity" without definition or qualification. Specifically, it does not mention anything about the BMI.

Diabetes

Finally, your ad refers to a study on the use of phentermine in obese diabetic patients in which patients treated with phentermine achieved a significantly greater weight loss than those treated with placebo.⁶ However, your advertisement does not mention that the study was short term only, nor that the difference was only achieved in patients using insulin and not in those on oral hypoglycemics. Your advertisement also does not mention that even for those patients who achieved temporary weight loss there was no effect on diabetic control, blood pressure or random serum cholesterol levels.

Questions:

1) Does 3M have any evidence that the short-term use of Duromine leads to long-term reduction in weight, total morbidity and total mortality?

2) Is 3M planning to revise its PI and promotion on Duromine to reflect current medical thinking that the minimum indication for treatment with drugs is a BMI greater than 27 kg/m²?

3) Does 3M have a written procedure to ensure that information is not selectively cited from studies?

I look forward to receiving your answers to all 3 questions.

Yours sincerely,

 

 

Dr Joel Lexchin MD, CCFP (EM), DABEM

Secretary, MaLAM Inc www.camtech.net.au/malam

cc A. Gastaldo, vice president, 3M Asia Pacific, R.O. Baukol, executive vice president, 3M International Operations.

 

1. Mansfield PR. MaLAM, a medical lobby for appropriate marketing of pharmaceuticals. Med J Aust 1997; 167: 590-592

2. Barlow J, Møller C. A complaint is a gift: using customer feedback as a strategic tool. Berrett-Koehler San Francisco 1996

3. National Task Force on the Prevention and Treatment of Obesity. Long-term pharmacotherapy in the management of obesity. JAMA 1996;276:10907-15.

4. Munro JF, MacCuish AC, Wilson EM, Duncan LJP. Comparison of continuous and intermittent anorectic therapy in obesity. BMJ 1968;1:352-354.

5. Proietto J. Anti-obesity drugs. .Med J Aust 1998;168: 8: 409-412

6. Campbell CJ, Bhalla IP, Steel JM, Duncan LJP. A controlled trial of phentermine in obese diabetic patients. The Practitioner 1977;218:851-855.