FEN-PHEN AND REDUX

Since 1968 clinical researchers have suspected that some prescription slimming pills cause heart damage. Fenfluramine was first implicated in 1981 as a possible cause of pulmonary hypertension. 1996 is the first year that physicians could be found negligent for PROACTIVELY failing to detect and prevent such injury to the heart.

Class-action products liability suits progress in the US and Canada, and the Federal Bureau of Investigation continues its enquiries into allegations that the manufacturers suppressed evidence of harmful effects. Meantime, malpractice litigators field occasional enquiries about actions against physicians for negligent prescription or monitoring of these drugs.

Both fenfluramine, alone (Ponderal or Pondimin) or combined with the drug Phentermine (Fen-Phen), and its variant dexfenfluramine (Redux) are members of one class of anorexigens (slimming pills) that alter metabolism of the neurotransmitter (brain hormone) serotonin.

Since 1968 clinical researchers have suspected that some prescription slimming pills cause heart damage. Soon after an earlier anorexigen proprietary-name Aminorex was licensed in Europe in 1965, Swiss, Austrian and German physicians noted ^{1 , 2} an epidemic of pulmonary hypertension, a condition in which increased pressure of the oxygen-depleted blood returning to the lungs causes breathlessness, intolerance of effort and fatigue³. The drug was withdrawn after 3 years, and causal link was eventually documented in 1979.

Fenfluramine was first implicated in 1981 as a possible cause of pulmonary hypertension. Meantime, in 1972 fenfluramine had been introduced into Canada for short-term use in the medical treatment of obesity, and in 1973 into the US. 1981 saw the first case reports implicating the drug as a rare cause of pulmonary hypertension ⁴.

1996 is the first year that physicians could be found negligent for PROACTIVELY failing to detect and prevent such injury to the heart. In 1993, a French team specialising in the disease were sufficiently concerned when they reported⁵ a case series of fenfluramine and pulmonary hypertension that they recommended a case-control study. Though that subsequent European international research documented ⁶ a clear causal link in 1996, the FDA saw fit to approve dexfenfluramine the same year.

A year later, in 1997, both the US and Canada withdrew both fenfluramine and dexfenfluramine as a result of a Mayo Clinic case series causally linking Fen-Phen additionally to heart valvedamage⁷ .

This saga illustrates the importance of considering the strength of medical evidence in determining standards of care. To date there are no cohort studies or meta-analyses to determine whether and how often fenfluramine and dexfenfluramine cause pulmonary hypertension and heart valve injury.

As the first decade of Evidence Based Medicine draws to close, it is important for lawyers providing services in the areas of Personal Injury and Medical Malpractice to realise that case reports and even case series are not adequate as a basis for Clinical Practice Guidelines or community standards of care. An apparent association does not prove a causal relationship .

With particular reference to these anorexigens and pulmonary hypertension, attending physicians did not have a specific onus until 1996 to look for the adverse effect. However, that does not absolve clinicians from the general responsibility to elicit and competently assess new symptoms arising during administration of therapy.

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