Biology 12

Chapter 1 The Chemistry of Life • MHR 19

Biology Magazine TECHNOLOGY • SOCIETY • ENVIRONMENT

The Thalidomide Dilemma

In the late 1950s, a new drug called thalidomide was

widely sold as a sleeping pill and cure for morning

sickness during pregnancy. Research had shown that

thalidomide is remarkably non-toxic, even in very high

doses. Tragically, tests did not show that the drug affects

the normal development and growth of a fetus. As a

result, thousands of women who had taken thalidomide

when pregnant gave birth to babies with missing or

malformed limbs, facial deformities, and defective internal

organs. The drug was banned for general use in 1964.

In the years since the catastrophe caused by thalidomide,

researchers have discovered more effects that the drug

has on the body. Not only does thalidomide induce

sleep and reduce nausea, but also it is a powerful anti-

inflammatory agent. It can also moderate extreme and

damaging reactions of the immune system. These effects

make it a valuable tool for treating leprosy, rheumatoid

arthritis, lupus, certain conditions associated with AIDS,

and other diseases. The dilemma is how to control and

market the use of a drug that can cause great damage,

yet has great benefits as well.

One Drug, Many Effects

It is quite common to find that pharmaceuticals developed

for one purpose have other applications. For example,

Aspirin™ was originally prescribed as a painkiller, but

much later was found to help prevent the formation of

blood clots. Prozac™ was marketed as an appetite

suppressant before it was recognized as an effective

antidepressant. Minoxidil™, used to control hypertension,

is now used to treat baldness. The interactions between

a particular drug and the body’s cells and organ systems

are often complex and poorly understood, even after a

drug has been in use for many years.

Thalidomide and Disease

How does thalidomide produce its effects? Since the

mid-1990s, scientists have learned that:

Thalidomide inhibits the movement of cells needed to

form new blood vessels. This is the property of the

drug that affects fetal development and results in

malformed limbs and organs. However, inhibition of

blood vessel growth also has important clinical value.

For example, cancerous tumours can only grow by

developing new blood supplies to provide them with

oxygen and nutrients and to carry away wastes. By

preventing the growth of new blood vessels,

thalidomide starves tumours and stunts their growth.

Thalidomide suppresses the production of a chemical

messenger called tumour necrosis factor, or TNF. This

chemical is made by blood cells as part of the body’s

immune response. However, large quantities of TNF

result in harmful inflammation — a common symptom

of autoimmune disorders such as rheumatoid arthritis,

AIDS, and lupus. Thalidomide is the most effective drug

known to relieve this symptom.

Thalidomide can be used to prevent the growth of

cancerous tumours.

The Bottom Line

With little or no toxicity and a wide range of applications,

thalidomide is a valuable drug for medical use. However,

the drug’s effect on babies born a generation ago still

makes its use controversial. The Thalidomide Victims

Association of Canada is a group of individuals born with

physical defects caused by this drug. They lobby drug

companies and governments to help ensure that another

generation does not experience the same effects as

they did.

Follow-up

1.Debate in class the arguments for and against

prescribing a therapeutic drug that has been proven

to pose serious health risks. Who should decide on

its use? What might be the view of a person who has

physical disabilities that were caused by thalidomide?

What might be the view of a person who suffers from

life-threatening symptoms of a disease (such as

AIDS) that thalidomide can relieve?

2.Thalidomide is dangerous to fetal development for

only a very short time in early pregnancy, three to

five weeks after conception. Other approved drugs

on the market, including an acne drug, also have side

effects that include producing fetal malformations.

What other examples can you think of where lack

of complete information might distort the evaluation

of a drug?