Severe extrapyramidal side effects when discontinuing clozapine and starting haloperidol

Reducing the Risk of Withdrawal Symptoms and Relapse Following Clozapine Discontinuation-Is It Feasible to Develop Evidence-Based Guidelines?

Clozapine is the only antipsychotic that is effective in treatment-resistant schizophrenia. However, in certain clinical situations, such as the emergence of serious adverse effects, it is necessary to discontinue clozapine. Stopping clozapine treatment poses a particular challenge due to the risk of psychotic relapse, as well as the development of withdrawal symptoms. Despite these challenges for the clinician, there is currently no formal guidance on how to safely to discontinue clozapine. We assessed the feasibility of developing evidence-based recommendations for (1) minimizing the risk of withdrawal symptoms, (2) managing withdrawal phenomena, and (3) commencing alternatives treatment when clozapine is discontinued. We then evaluated the recommendations against the Appraisal of Guidelines for Research and Evaluation (AGREE) II criteria. We produced 19 recommendations. The majority of these recommendation were evidence-based, although the strength of some recommendations was limited by a reliance of studies of medium to low quality. We discuss next steps in the refinement and validation of an evidence-based guideline for stopping clozapine and identify key outstanding questions.

Mechanisms of action of antipsychotic drugs of different classes, refractoriness to therapeutic effects of classical neuroleptics, and individual variation in sensitivity to their actions: Part II

Rapid-onset psychotic rebound is uncommon on discontinuation of most antipsychotic drugs, as might be expected for antipsychotic drugs with (hypothetically) indirect actions at their final target receptors. Rapid-onset psychosis is more common on withdrawal of clozapine, which might be expected if its action is direct. Drugs other than clozapine (notably thioridazine) may have hitherto unrecognised similarities to clozapine (but without danger of agranulocytosis), and may be useful in treatment of refractory psychosis. Quetiapine fulfils only some criteria for a clozapine-like drug. Clinical response to neuroleptics varies widely at any given plasma level. Haase's "neuroleptic threshold" concept suggests that the dose producing the slightest motor side effects produces most or all of the therapeutic benefit, but analyses presented here suggest that antipsychotic actions are not subject to a sharp "all-or-none" threshold but increase over a small dose range. This concept could provide a method for quantitative determination of individualized optimal doses.

Risperidone Withdrawal-Related Respiratory Dyskinesia

Risperidone is a frequently used member of a new class of atypical antipsychotics-the serotonin-dopamine antagonists (SDAs)-due to its comparatively high efficacy and low D2/5HT2 binding ratio, which results in a low incidence of extrapyramidal side effects including tardive dyskinesia (TD). The authors present an elderly patient with mixed dementia who developed TD at multiple sites, (including respiratory dyskinesia [RD], limb dyskinesia, and orofacial dyskinesia) following abrupt withdrawal of risperidone therapy. RD is not a rare condition, but is often misdiagnosed and is potentially lethal. Therefore, clinicians should pay close attention to possible onset of RD in patients with multiple risk factors for TD, even when SDA therapy is used. If RD is suspected, assessment should include spirography combined with fibroscopy for examination of irregularities in the rate, rhythm, and depth of respiration.

Switching atypical antipsychotics: a review

BACKGROUND

Atypical antipsychotics are increasingly used in the treatment of diverse psychiatric disorders; however, there is little information on the 'why, when, and how' of switching between the different atypical antipsychotics currently available.

OBJECTIVE

To review the data on switching and atypical antipsychotics.

METHODS

A literature search was initially conducted using the key words followed by a search of relevant articles including conference abstracts; relevant pharmaceutical companies were also contacted.

RESULTS

Clinical trial data are limited in terms of parameters measured, and case reports describe specific problems. Few studies are based on real world populations of psychiatric patients over the long-term. Careful patient and drug selections matched to a carefully supervised and appropriate cross titration based upon the pharmacodynamic and pharmacokinetic properties of all of the drugs involved is important to avoid potential complications such as re-emergence or worsening of psychosis and withdrawal, rebound, and emergent phenomena including new or uncovered side-effects. Psychoeducation and involvement of patients and caregivers in the process are also necessary for a successful switch.

CONCLUSION

Despite the prevalence of switching in real world clinical practice, there is a paucity of data to guide clinicians with respect to effective and safe strategies. There are no criteria defining a successful switch. With the increasing range and formulations of atypical antipsychotics available, there is a rationale for their early use to avoid the practical problems associated with switching from conventional antipsychotics as well as the opportunity to maintain patients on an optimal atypical antipsychotic monotherapy.