Read any of the popular press (as opposed to the
scientific medical press such as the Lancet, for example) and you
will read about vaccines being developed to save us all from AIDS, cancer,
next year’s giraffe flu and halitosis.
Unfortunately, the next generation vaccines and drugs are
still in the testing phases, because they need rigorous testing. Remember that
in 1976 a vaccine was rushed through by order of an American president, and I
believe more people died from the vaccine than died from the flu from which it
was supposed to protect the public. It also left a large number of people with a
nasty condition called the Guillain-Barr้ syndrome, and about 30 percent of
those with Guillain-Barr้ still have a residual weakness.
Have you ever wondered just how a new drug finds its way on
to the pharmacist’s shelves? Just how do the pharmaceutical companies manage to
develop newer vaccines and drugs such as ACE inhibitor antihypertensives when
there were already plenty of alternatives? Or the apparently stiff competition
in the drugs for males with Erectile Dysfunction. (I am sure you have all been
receiving emails every day offering you longer and stronger lead for your
particular pencil!)
However, when any new medication is formulated, there begins
a very long process before the new “wonder drug” is licensed for use by the
public. Part of that process is testing the compound on live beings. Note I did
not say “human” beings. Those live beings are usually convenient test animals,
of which Mr. Rat the rodent is a prime example.
We always need to know how poisonous is the new drug. Mr. Rat
is then fed the new compound in ever increasing quantities until the dose high
enough to kill 50 percent of the rat population is reached. The scientists call
this the LD50 (Lethal Dose for 50 percent) for the new compound - but remember
this is for rats. If it takes 10 mg of compound A to kill 50 percent of the
rats, but only 1 mg of compound B, then B is 10 times stronger than A.
Pregnant Mrs. Rats are also fed the new drug and the
offspring are thoroughly examined to see if there are any abnormalities, greater
than the ‘normal’ amount of expected abnormalities. Yes, no animal, including
us, is without a usual percentage of birth abnormalities. Laboratory rats in
particular are well known for being able to develop all sorts of abnormalities
if you even just look at them sideways!
Only after this exhaustive testing is the drug then used in
limited test runs on a very limited human exposure group. And, by and large,
that does not include testing on productive age females.
All this takes an enormous length of time, so next time you
read of the new wonder drug “breakthrough” do not expect that this will appear
in the pharmacy next week. Unfortunately too, many of these new drugs will end
up never being released as further research often turns up problems that only
made themselves apparent after long term usage.
However, even the ones that do get released have to be
approached with caution. Just because rat testing appeared to show that the drug
was “safe”, does not mean that humans will also react the same way. As the
caption this week says, Man is not a large Rat! This is one reason why women in
particular must be very careful with the drugs they take during pregnancy,
particularly in the first three months, that time when the growing fetal
structures are susceptible to toxic chemical damage. In fact, any woman who has
to take regular medication should ask her obstetrician about the relative risks.
However, this does not mean stop taking the tablets as soon as you miss a
period. Letting the maternal problems run unchecked can be an even greater risk
to the baby than the risk from the medication taken by Mum.
Antenatal care is a very specialized branch of medicine and I
do recommend you should ask your obstetrician for advice. You may not be a rat -
but you don’t want to be a guinea pig either!
