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VOL. 70 (3), 663-679, 2004 PHARMACOKINETICS AND INDIVIDUALIZED DRUG THERAPY

is not true. Many drugs have such a wide margin between good
effects and side effects so if you do not observe an effect; it is just
to increase the dose until you observe an effect. If you then do not
get a therapeutic effect you may have to change drug.

Suitable drugs for TDM are of course drugs that are going to be
used by the patients for a long time and where it is important that
you find the correct dose and dosing interval in order to get the best
therapeutic effect with a minimum of side effects. I will give you
some examples of classes of drugs we have been working with in
Uppsala.

Immunosuppressant drugs have to be taken in order to avoid
organ rejections after transplantation, psychoactive drugs used to
treat e.g. psychosis, antiepileptics, cardioactive glycosides and blood
factors for hemophilia are examples of drugs used for long times, in
certain cases for the whole life. Other examples are antibiotics and
tuberculostatic drugs, where it is critical for the treatment that the
correct concentration in the body is achieved otherwise the bacteria
may become resistant. Anticancer drugs are a group of drugs that
are used under the philosophy that it should be given in as large
doses as possible, with the limitation that the patient can manage
the serious side effects. There are still much to do with these drugs
in order to improve the cancer therapy and I think that TDM is one
way to optimize cancer treatment.

THERAPEUTIC DRUG MONITORING TODAY

There are performed a lot of drug chemical analyses at the hos-
pitals all over the world. In Sweden there is analysed about 600.000
blood samples per year in a population of about 8 million. The
question is of course how these measurements is interpreted. In
Sweden, I may say, most medical doctors look upon the values just
to find out if they fall within by the manufacturer recommended
concentration range, without any, I may say, deeper consideration.
If the value falls within the range, the prescribed dose is correct
(Figure 3).

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