Use of concomitant medication in the treatment of schizophrenia

Abstract

Purpose of the study: Schizophrenia is a life-long, disabling psychiatric condition that requires continuous pharmacotherapy. Between 10% to 30% of patients with schizophrenia show poor response to antipsychotic medication alone [1]; therefore concomitant medication is often used. The rationale for the addition of concomitant medication is however often unclear and based on limited evidence. The aim of this study was to determine the extent and need for concomitant medication in the treatment of schizophrenia. Methods: This is a randomized, retrospective study, investigating use of concomitant medication as adjunct to antipsychotic medication in the treatment of schizophrenia. The study population included randomly chosen adult (≥ 18) inpatients in a psychiatric unit, receiving treatment with antipsychotic medication. Results: Descriptive analysis of data indicate 91.7% of patients receiving treatment with antipsychotic medications, also received concomitant medication - 16.7% received only one concomitant drug; 25% received two concomitant medications, and 13% received three types of concomitant medication in conjunction with an antipsychotic. Anxiolytic medication (most often benzodiazepines) were the concomitant medication prescribed most often in combination with antipsychotics (66.7%), followed by anticholinergic medication (12.5%), mood stabilizing drugs (8.3%) and antidepressant medication (4.2%). Indications for concomitant medications range from controlling specific symptoms associated with schizophrenia eg anxiety symptoms, aggressive behavior and suicidality, to managing adverse effects eg parkinsonian side effects [2] caused by antipsychotic medication. Analysis using a Pearson's chi square to determine the use of concomitant medication and presence of adverse effects; although not statistically significant (p = 0.148), there seems to be a higher incidence of adverse effects experienced by patients taking concomitant medication (79.2%) when compared to patients not receiving any concomitant medication (20.8%). While concomitant medication can be used to counteract adverse effects of antipsychotic drugs, addition of concomitant medication to antipsychotic treatment is also associated with a higher incidence of adverse effects. The reason for this being that concomitant medication contributes to the already existing side-effect profile of antipsychotic drugs e.g. although anticholinergic medication proves beneficial in counteracting extrapyramidal side-effects associated with antipsychotic drugs, it has also been found to impact negatively on cognitive functions, including attention and concentration, attenuating the effects of antipsychotic drugs. Conclusion: Due to the complexity of schizophrenia and the difficulty with adequate management of the disease with antipsychotic medications alone, indications exist for the use of adjunctive medication. These indications include management of adverse effects caused by antipsychotic medication, augmenting the action of antipsychotic medication, and addressing specific symptoms of schizophrenia not adequately addressed by the antipsychotic medication alone. The use of concomitant medication can, however, increase the risk for adverse reactions and drug interactions, as well as impact adversely on compliance and cost of treatment, and therefore needs to be considered carefully before implementation. The choice of specific treatment regimen is best guided by the clinical characteristics and presentation of the individual patient as no one adjunctive treatment combination benefits all patients.