More than ten years of research and clinical observations have shown that the SI-5HTs have a therapeutic effect on different depressive disorders and that they are particularly useful in out-patient practice. In comparison with classic antidepressants (tricyclics), they are usually tolerated better and, to a certain extent, safer. The SI-5HTs are also recommended in obsessive-compulsive disorders where their positive effects have been well-documented. This group of drugs may also have therapeutic value in other disorders but this has not yet been fully confirmed.
The SI-5HTs are a heterogeneous group of psychotropic substances which share a common factor, i.e., they inhibit serotonin uptake. They are heterogeneous with respect to their specific mechanisms, including g their effects on different CNS structures, their pharmacokinetics, their psychotropic action profile, adverse side-effects, and interactions with other drugs. These factors must be taken into consideration when we select SI-5HT for a given patient.
The SI-5HTs need further studies, both in basic research and c1inical investigations. Further studies should involve, in particular: comparison of the different SI-5HTs with each other with respect to their psychotropic action profile s in the depressions and their effectiveness in the treatment of severe depressive states (melancholic, psychotic) in different sub-populations (adolescents, the elderly), in the prevention of recurrent depressive disorders and in other well-defined or potential indications.
The safety of long-term treatments using the SI-5HTs (particularly their effects on the extrapyramidal and cardiovascular systems) and of their combination with other drugs must also be determined.
The main reason why new drugs (including antidepressants) are continually being developed is the need to find better medications than those currently in use in terms of their effectiveness, speed of action, breadth of therapeutic index (lower risk of toxicity in case of overdose), better tolerance, narrow range of counter-indications and fewer interactions with other drugs. The SI-5HTs only partly answer these demands, i.e., they have a broader therapeutic index, are tolerated better, safer to use and have fewer counter-indications than classic antidepressants. But on the other hand the SI-5HTs are not more effective than the TADs (some clinicians even think they are less powerful than the tricyclics), they do not act more quickly and their interactions with other drugs will probably cause more and more problems. Despite these shortcomings, implementation of the SI -5HTs to clinical psychiatry must be viewed as a sign of progress in the treatment of the depressions and probably obsessive-compulsive disorders as well.