[Practical aspects of drug resistance in schizophrenia]

About 30-60% of patients with schizophrenia show resistance to neuroleptic treatment. In about 5-20% of them the resistance to antipsychotic treatment appears during the first therapy (primary resistance), however in the rest of patients, treatment resistance develops during 5 to 10 years of the illness (secondary resistance). In addition, another group of 5 to 20% of schizophrenics shows intolerance of therapeutic dosages of neuroleptic drugs. Before the diagnose of treatment resistance has been made, there is the need to reconfirm the diagnosis of schizophrenia, exclusion of other psychiatric disorders, assessment of patients' compliance, drug dosing, as well as pharmacokinetic and pharmacodynamic factors which have an impact on the therapeutic effect of antipsychotic treatment. Clozapine seems to be a "gold standard" for treatment of drug-resistant schizophrenic patients, however new atypical antipsychotics should be considered as a new therapeutic strategy, even before clozapine. The use of adjunctive treatment with carbamazepine, lithium, valproic acid, benzodiazepines and others, is a reasonable strategy, however dangerous drug interaction has to be taken into account.