Switching patients from one antipsychotic to another can be challenging and requires an awareness of the differences and similarities of the two agents’ pharmacological profiles. With each antipsychotic substitution, there is risk of relapse, toxicity and withdrawal symptoms (such as anticholinergic withdrawal and rebound dyskinesias). Unfortunately, attempts to limit one risk may increase another. Overlapping therapies can decrease the risk of relapse, but this increases the risk of toxicity and may not prevent withdrawal symptoms . For example, patients switching from clozapine to risperidone are at risk for early relapse, which risperidone may limit by overlapping the therapies. buy ortho tri-cyclen
However, switching abruptly from an agent with potent anticholinergic activity to one with low muscarinic binding (eg, clozapine to risperidone) results in a risk of rebound in cholinergic activity with the removal of clozapine therapy. Furthermore, past clozapine therapy is unlikely to mitigate the risk of early dystonia with aggressive dosing of risperidone . This is due to their potency differences at D2 receptors. Switching from risperidone to clozapine may be somewhat less troublesome, particularly by overlapping therapy gradually and cautiously, for example over one week as a minimum and longer if the titration of clozapine is slow (less than 100 mg/week). Relative potencies at D2 and muscarinic receptors are shown in Table 2 and can be used to predict potential risks during antipsychotic treatment switches.