The Real Story Behind Using Two Antipsychotics For Schizophrenia

It wasn’t that long ago when I was sitting in lectures as a first-year psychiatry resident. I learned about the first- and second-generation antipsychotic medications in detail. One commandment that was always preached in my training was to never combine two antipsychotic medications because there is no additional benefit. Today we are here to explore this idea and see if there is truly no additional benefit to using two antipsychotics and explore why there is so much antipsychotic polypharmacy in serious mental illness.  

Introduction

While all training programs preach the use of mono-therapy when it comes to the use of antipsychotics in clinical practice, the reality is up to 50% of psychiatric inpatients are receiving antipsychotic polypharmacy

Since most guidelines discourage the use of multiple antipsychotic medications, why are many psychiatrists going against these guidelines? In most cases we are just trying to stabilize patients, get them better, and keep them out of the hospital as the goal is to provide most psychiatric care in the community. To reach these goals a single medication does not always produce the desired results. 

Patients that end up on multiple antipsychotics have some unique characteristics. They tend to have more severe psychotic symptoms, are male, unemployed, and younger. Those with frequent inpatient admissions on involuntary status are also more likely to end up on two medications. 

What To Do When a Single Medication Is Not Enough?

The use of multiple antipsychotics is an area of limitted research. However, there is a difference between rational polypharmacy and irrational polypharmacy.

We should start this discussion by saying a patient should be started on monotherapy titrated to an effective dose and continued on the medication for 6 weeks prior to making a change. If the first medications fails, then switching to another medication or long acting injectable is a reasonable next step. If after another 6 weeks of treatment the patient remains unstable and symptomatic the technical next step is to start clozapine. There are many reasons why clozapine may not be a good option for a particular patient including the strict requirements for weekly complete blood cell counts CBCs.

Assuming this process is followed and the patient is still symptomatic what’s the next step?

Consider Receptor Binding Profiles

This is the first step in prescribing two medications rationally. Most first-generation medications such as Haldol will bind tightly to D2 receptors and stay bound to the sites longer. Second-generation medications like quetiapine are known to bind to the receptors and quickly dissociate giving an on-off like effect. Tight binding and longer duration of binding can lead to extrapyramidal side effects (EPS), whereas quick on-off medications like quetiapine have limitted EPS risk. 

You should also consider other receptors the medication may target such as histamine and muscarinic cholinergic receptors. It would be best to avoid combining two medications that have high antihistamine and anticholinergic activity.

Let’s look at some scenarios where antipsychotic polypharmacy makes sense. 

Patients With Acute Agitation

This is a common problem on the inpatient unit. A patient is on a low-potency quick on-off medication like quetiapine but remains symptomatic and is engaging in dangerous behavior. 

The addition of a higher potency, higher affinity medication like Haldol makes some sense here. This will control the acute agitation, can be titrated until the psychotic aggression is controlled, and can be stopped as soon as the patient is stable on quetiapine. We can see how the receptor binding profile makes this combination reasonable.

Clozapine Refractory Patients

What do you do when a patient is on the best antipsychotic medication but remains symptomatic? 

We do have several lines of evidence that we can look at for this question. One option is to add low dose risperidone. This is a similar idea to adding Haldol to quetiapine. Clozapine has lower affinity for the D2 receptor than risperidone which has much higher affinity for D2 receptors. There were two placebo-controlled trials that support this combination. Before combining medications, I would suggest obtaining a clozapine level to make sure it’s therapeutic. 

There are two more recent studies that compared multiple antipsychotic medication combinations and used rehospitalization as a measure of effectiveness. Both studies found a significant reduction in rehospitalization for patients receiving polypharmacy compared to those receiving monotherapy. The best outcome was achieved when clozapine was combined with aripiprazole

Patient is On a Long Acting Injectable (LAI) but Remains Symptomatic at the Highest Dose 

This is a common problem because the doses of LAIs are limitted. For example, the LAI aripiprazole (Aristida) is limitted to a maximum dose of 20 mg/day. The oral formulations of aripiprazole allow for a maximum dose of 30 mg/day. One strategy is to give the injection early. This will usually be done on week 3 for formulations that last 4 weeks. Another option is to add another medication with a different receptor binding profile such as the clozapine aripiprazole combination that was shown to reduce the risk of rehospitalization.

Treatment of Insomnia 

The addition of low dose quetiapine to a medication like paliperidone is common in clinical practice. Once D2 receptor blockade has been maximized by reaching an effective dose of paliperidone, considering the addition of as need (PRN) quetiapine for its low potency and sedating properties is reasonable. The medication should be used PRN only and should be removed once the insomnia has resolved. Consider a sleep study if sleep apnea is possible and using other options such as short-term orexin antagonists, melatonin, and sedating antidepressant if appropriate. 

Treatment of Antipsychotic Induced Side Effects 

I know what you are going to say, adding a medication to treat a side effect of another medication doesn’t make sense. Let’s take an example to illustrate why this makes sense. If a patient is stable on risperidone and is discovered to have an elevated prolactin level you have an obligation to address it. The addition of low dose aripiprazole has been proven to reduce prolactin levels in these cases. Another possibility is using aripiprazole to reduce the metabolic burden of medications such as clozapine. There is much more limited data in this area and I would consider metformin a much better option to start with if antipsychotic induced weight gain is a problem.

In the process of Switching Medication the Patient Achieves Remission 

This is another common clinical scenario. A patient didn’t respond to a medication, and you begin decreasing the dose of the first medication while titrating the new medicine. Then suddenly they are better. You don’t know why but they are better than they have ever been and now you are afraid to make any additional changes. Ideally you would finish the process and appropriately titrate the new medicine while discontinuing the ineffective medication. There is no good data to support inadequate dosing of two antipsychotics, and it’s best to continue your taper/titration and reevaluate after it’s complete.

Conclusion

There is still limited data to support the use of multiple antipsychotic medications although it is often seen in clinical practice. There are a few places where the addition of a second medication makes sense, and we can use receptor profiles to help us make rational decisions and avoid excess side effect burden. 

The Best Antipsychotic Medication in The World 

Introduction:

I’ve said it before in previous videos, older medications are more effective and newer medications have fewer side effects. 

The advent of SSRIs in the late 1980’s and early 1990’s was largely driven by safety and not efficacy. The same is true for antipsychotic medications. This may be the reason most people haven’t even heard about Clozapine (brand name Clozaril). 

Efficacy

Clozapine is the single most effective antipsychotic available, and it works in treatment resistant schizophrenia where no other medication is proven to be effective. 

The results speak for themselves, 30% of previously treatment resistant patients experience symptom reduction within 6 weeks and that number jumps to 60% after 6 months of treatment. 

Clozapine has a slew of additional benefits including mood stabilizing prosperities (it can be used in bipolar disorder), reduction in psychogenic polydipsia and the hyponatremia associated with it, reduction in hostility and aggression, reduction in the risk of suicidal ideation, improvement in substance use, and it may even help patients quit smoking a difficult task in schizophrenia. 

So why are most schizophrenic patients not on this medication if it’s so great? 

Side effects, side effect, side effects

-Sedation: feeling tired this can largely be mitigated by dosing the medication at night before bedtime. 

-Tachycardia: It’s worth getting an EKG in patients with preexisting heart conditions or those at high risk due to hypertension and hyperlipidemia 

-Sialorrhea: excessive saliva production leading to drooling, no one wants this 

-Dizziness

-Constipation: this should be addressed immediately if a patient complains about it as it can lead to serious complications. In many cases Senna and Colace will do the trick

-Orthostatic hypotension 

-Weight gain 

Serious and potentially fatal Side effects include: 

-Agranulocytosis: decreased absolute neutrophil count which can result in increased risk for serious infection and the reason everyone on the medication gets weekly blood draws for the first 6 months 

-Seizures: clozapine is known to lower the seizure threshold 

-Myocarditis: inflammation of the heart usually due to a viral infection 

The risk for agranulocytosis is highest when starting treatment, usually during the first year of treatment (0.8%) and the maximum risk is between 4 and 18 weeks (when 77% of cases occur), although it can still occur at any point in the treatment.

Agranulocytosis

Monitoring is thus very important, and each patient must be registered in the Risk Evaluation and Mitigation strategy (REMS) data base before starting the medication. 

A CBC with differential must be drawn to calculate the absolute neutrophil count prior to starting treatment and then weekly for the first 6 months. Then monitoring continues every 2 weeks for the next 6 months and finally monthly after the first year of treatment. 

If agranulocytosis occurs stopping clozapine allows majority of cases to recover within 14 days. 

Now that we know that this medication is very effective but comes with a high side effect burden a natural next question might be why does the medication work? 

Mechanism of Action

Clozapine has very low affinity for the D2 receptors which is unique as most other antipsychotics will bind strongly to D2 receptors. Clozapine had far greater D1 and D4 binding affinity, blocking both receptors. 

Clozapine also has significant activity at other neurotransmitter sites. It blocks alpha receptors which may be the reason for orthostatic hypotension. It blocks histamine H1 receptors resulting in sedation and weight gain. It blocks 5-HT2A serotonin receptors and is highly anticholinergic resulting in constipation and urinary retention. 

It has two unique properties; it influences the glutamate system by altering NMDA receptor sensitivity and increases the release of brain derived neurotrophic factor BDNF. 

Metabolism And Drug Interactions

Clozapine is primarily metabolized by CYP450 1A2 and 3A4 and cigarette smoking will cause a reduction in clozapine levels due to induction of CYP 1A2. 

Before Starting the Medication

Before starting clozapine, the ANC must be above 1,500. If neutropenia develops treatment will depend on the severity of the drop. 

Mild Neutropenia: ANC 1,000-1,499, you would continue treatment and check an ANC three times weekly until it reaches 1,500. 

Moderate Neutropenia: ANC between 500 and 999, stop treatment and check the ANC daily until it reaches 1,000 then 3 times weekly until it reaches 1,500 then weekly for 4 weeks before returning to the patients prior monitoring schedule. 

Severe Neutropenia: ANC less than 500, stop treatment and check an ANC daily until it’s 1,000 then 3 times weekly until it’s 1,500. The patient should not be rechallenged without a hematology consult and clear benefits that outweigh the risks. 

Dosing

Clozapine can be started at 12.5 to 25 mg at bedtime. The dose can be increased 25 mg/day inpatient and 25 mg per week in the outpatient setting as tolerated. 

You can overlap prior treatment with another antipsychotic and tapper the old medication once clozapine dose reaches 100 mg or more. 

Plasma Levels

Clozapine dose should be based on serum levels, with a target blood level of 200 to 300 ng/ml. If there are still symptoms present the target serum level is 450 ng/ml. There are no benefits to serum levels above 900 ng/ml. 

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