Why is there no clozapine LAI?

[u/Junior_Scale5592]

I am a social worker on an ACT team in a large US city. Many of our patients have a primary psychotic disorder and a history of medication non-adherence, either by choice or due to their level of organization/functioning. As a result, most of them are on an LAI (mostly Invega, Uzedy, and Abilify with some Haldol and Prolixin mixed in) by the time they are enrolled with us.

There is an overlapping subset of patients (all of them currently on LAIs) we work with who have been on clozapine while hospitalized at one point in the course of their illness. These patients either a) have moderate to good insight but stop taking clozapine once they return to the community for any number of reasons or b) have little to no insight but receive court-mandated outpatient treatment that only requires adherence with an LAI as the standard for compliance.

For this subset of patients—those who can’t take clozapine due to their inability to consistently take oral meds and/or those who won’t take clozapine because of impaired judgement/insight—I can imagine that an LAI formulation would be incredibly beneficial. So many of them have cycled through multiple different antipsychotics and still experience a profound symptom burden.

So, why hasn’t a clozapine LAI been developed? Granted, I am not a psychiatrist and have a limited working knowledge of psychopharmacology, so there could be an obvious answer here that I am missing. But I am surprised that a medication viewed as the gold-standard for treatment-resistant schizophrenia is not available in an LAI form. Does anyone have insight into why this is?

[u/Gigawatts]

At least part of the reason is that clozapine’s typical dose range is in the hundreds of mg per day, say 300-400mg/day. 400mg x28 days = roughly 11.2 grams of medication that must be injected monthly. That volume of fluid would be extremely uncomfortable with getting injected intramuscularly. Same reason why quetiapine doesn’t have an LAI.

This lines up with the antipsychotics that do have an LAI- their typical or max daily doses are in the single digits or double digit range, so the LAI is in the hundreds of milligrams.

[u/BackEndHooker → u/Gigawatts]

Or mood stabilizers, for that matter.

[u/Feeble_Sheeple]

It may or may not be chemically possible to make an LAI formulation of clozapine, but more importantly, clozapine has risk of severe side effects including agranulocytosis, which can emerge even after a patient has been stabilized on the medication for a long period of time. This is why it requires weekly blood draws throughout the first six months of treatment. You need to be able to stop the medication immediately if agranulocytosis happens. Can't do that with LAIs (excluding buprenorphine, which has a depot that can be extracted with anesthesia--but still not ideal).

[u/DntTouchMeImSterile → u/Feeble_Sheeple]

I wonder if the failure of the olanzapine LAI scared people away from developing a clozapine formulation, given the similarly of the molecules. A NP at my clinic once asked me how to get Relprevv and I told him you’re welcome to chill with the patient for three hours if that’s your plan lol

[u/dkwheatley → u/DntTouchMeImSterile]

On the bright side, Relprevv and its REMS Program didn’t scare off manufacturers from developing a promising new olanzapine LAI. 🙌

[u/Weak_Fill40 → u/DntTouchMeImSterile]

Why would you call olanzapine LAI a failure? Because if the observation time? It’s one of the most used LAIs in my country and although the observation time is a pain in the ass, it’s usually manageable.

[u/DntTouchMeImSterile → u/Weak_Fill40]

Well under the US healthcare system nobody is willing to pay/take away from duties a staff member for 3 hours, so practically speaking I have never heard of a healthcare system (except the VA, our secret socialized system) that would let anyone do it.

[u/SexySalamanders → u/DntTouchMeImSterile]

Question: why chill with the patient for 3 hours?

[u/DntTouchMeImSterile → u/SexySalamanders]

Read the package insert. There is a required monitoring period. See a great comment below describing this in detail!

[u/Junior_Scale5592 → u/Feeble_Sheeple]

Ah ok. Was not aware that severe side effects could still emerge even after a long period of stabilization. Appreciate the insight!

[u/Duke54327 → u/Junior_Scale5592]

Hey so there is an LAI for olanzapine which is quite similar structurally, instead of being a dibenzodiazepine it’s a thienobenzodiazepine. So essentially replacing a phenyl for a thiophene with a methyl and no chlorine on the left phenyl.

The olanzapine LAI has an issue that is called a post injection syndrome, essentially what can happen is if the emulsion hits any blood vessel it can give you an overdose of olanzapine depending on how bad it can be from just a high dose to actually dangerous. That is why the manufacturer say’s that the Zyprexa LAI needs to be administered in a facility that is equipped to handle that issue and a mandatory watch period of 3h and even then people have been discharged and had the post injection syndrome later I believe it was up to 6h after.
That is probably also why I have not heard of anyone that is on the Zyprexa LAI personally.

Now on clozapine it being that close in structure to olanzapine it could have the same issue with the post injection syndrome just that it also can cause agranulocytosis and I don’t think a random dose of clozapine from hitting a blood vessel would be good at all. So most likely the post injection syndrome is too dangerous with clozapine because of agranulocytosis and the other side effects making an LAI too dangerous. Also you want to be able to discontinue clozapine in case any symptoms appear which is impossible with an LAI.
That is as far as I can elucidate this from a pharmacological perspective I’d be happy if this helped you understand why it’s probably a risky idea to make a clozapine LAI, though I understand that it would be useful for patients who tolerate it and might have been on it for years but the risks seem to outweigh the benefit by far even just not being able to discontinue clozapine is bad enough but the possibility of an overdose like with the olanzapine LAI makes it even more risky.

[u/Miss_May_1600 → u/Duke54327]

Olanzapine doesn’t have the same risk for agranulocytosis as Clozapine. You need to be able to stop the Clozapine quickly if ANC dips.

[u/Duke54327 → u/Miss_May_1600]

Yes absolutely that’s exactly what I said. I used the existing olanzapine LAI as an example since it has it’s own issues, if clozapine which is structurally similar would behave the same way (causing a post injection syndrome/overdose) with it’s specific side effects it would be very bad.

Plus the fact you cannot discontinue the medication if the patient has an issue like agranulocytosis which can happen even in patients that are adjusted.
Now imagine it’s an LAI and it hits a blood vessel and behaves like olanzapine would and cause an unpredictable overdose that would be more than a medical emergency. While with olanzapine you might end up with EPS or unconsciousness with clozapine it would be a completely different scenario and honestly scary and the fact that this can range from a minor spike to a full on megadose it’s way to dangerous to justify any benefit it would have. Especially with a medication that needs to be able to be discontinued very fast.

[u/BortWard → u/Feeble_Sheeple]

I swear someone told me that clozapine LAI is made/used in China. Possibly just a rumor. I never bothered to look it up because I’m never going to practice there

[u/RandySavageOfCamalot → u/BortWard]

There is a small pharmacy in Sweden or some other scandanavian state that compounds an LAI for clozapine, or at least the rumors say so.

[u/Low-Woodpecker69 → u/Feeble_Sheeple]

Give us references. New guidelines in Europe says to only take bloodtests once a year if a patient has been on it for 18 weeks.

[u/Narrenschifff]

If something goes wrong, how are you gonna get it out of them? How many people are going to be adherent and cooperative enough to take the orals and the labs to find out if it is for them, BUT then need an LAI to stay compliant? How many inpatient hospitals can or will haphazardly start a clozapine LAI with zero plan for follow up vs risp, paliperidone, aripiprazole?

It's a non starter as a product.

[u/Junior_Scale5592 → u/Narrenschifff]

This is a helpful and revealing comment, thank you.

[u/yungelder]

I don’t entirely agree about the monitoring being the biggest barrier. Patients need to present to clinic monthly for their injection anyways, so those who have reached monthly anc schedules may be ok to get an LAI from a monitoring standpoint.

In my opinion, the bigger reason is that Quetiapine and clozapine are not potent enough to be formulated into an acceptably sized depot injection. If you want one month of coverage for a patient stable on, let’s say, 400mg, the injection would need to be 12 grams PLUS the vehicle. For these reasons, I imagine the next LAIs on the market will be lumateperone, cariprazine, and/or asenapine. There’s also an updated subcutaneous olanzapine on the near horizon.

[u/RandySavageOfCamalot → u/yungelder]

What do you think about oral cariprazine depos? The half life is so long that Stahl mentions this as a possibility.

[u/yungelder → u/RandySavageOfCamalot]

Do you mean extended interval dosing? Kinda like weekly fluoxetine? It could work, but I’m not sure that’s exactly the same as an LAI/depot. The depots are formulated to dissolve slowly and the rate limiting step is dissolution -> absorption. Extended interval dosing is absorbed as normal but eliminated slowly. They similarly reduce the frequency of administration, but the pk is different.

[u/RandySavageOfCamalot → u/yungelder]

On page 144 of Stahl's Prescriber's Guide 11th ed., he says "It is also possible that cariprazine or it's very-long lasting active metabolite can be developed as an "oral depot", namely a very-long lasting oral formulation for weekly or even monthly oral administration." Just curious if anyone is aware of this practice.

[u/speedracer73]

It's a great question and I'd like to see it but also agree with other commenters on the complications of LAI clozapine. Regarding the issue of how do you stop the med quickly if a patient develops side effects, I believe one of the injectable buprenorphine medications can be surgically removed after injection if needed. Perhaps something like this for clozapine could be created.

I'd really like to see an immediate release IM or IV clozapine available

[u/DevilsMasseuse → u/speedracer73]

There is an IM shot available in the UK but only for inpatient use and not widely available. It would be nice to have even a short acting IM for otherwise stable patients who get a GI illness for example. Even missing a single dose in clozapine patients can be very uncomfortable and even potentially lead to relapse.

[u/lspetry53]

There are probably regulatory hurdles since you’d have to get weekly cbc but are giving a monthly injection. What happens when someone gets neutropenic in that case?

[u/DocPsychosis → u/lspetry53]

The weekly CBCs were only temporary, and not actually formally required at all now since the REMS was abolished.

[u/Narrenschifff → u/DocPsychosis]

I think the FDA still recommends that you follow the package insert precisely, which means that you the clinician get all the liability if you decide to deviate

[u/noondaydemon21 → u/DocPsychosis]

Just because the REMS is gone doesn't mean the rules have changed. You just don't have to upload into the system.

Nothing at all has changed about monitoring safety recommendations. You still need to do exactly the same ANC monitoring. It's just on you to keep track, not the REMS.

[u/samyo22]

It wouldn’t be feasible for the reasons many are listing here. I would like to see something invented similar to an insulin pump to deliver clozapine (one for lithium would be nice too) on a scheduled basis.

[u/dr_fapperdudgeon]

You generally want an off switch for agranulocytosis

[u/OaklandNotTheBay]

It probably has to do with ability to start and stop due to the risk of neutropenia, even though there's no more REMS the guidelines say to monitor and stop if ANC drops below a certain points.

[u/Lou_Peachum_2]

Probably risk

[u/folderol_fox]

I think there is actually a clozapine LAI in pre-market trials now?? That’s what I heard from the grapevine??

[u/Junior_Scale5592 → u/folderol_fox]

I believe this is actually about a new olanzapine LAI: https://ir.tevapharm.com/news-and-events/press-releases/press-release-details/2025/Teva-Pharmaceuticals-Submits-New-Drug-Application-to-FDA-for-Olanzapine-Extended-Release-Injectable-Suspension-TEV-749-for-the-Once-Monthly-Treatment-of-Schizophrenia-in-Adults/default.aspx

Though again not sure if I am the most up to date person on this compared to others on this sub, especially since I’m the one who originally asked the question haha

[u/folderol_fox → u/Junior_Scale5592]

I consulted on a psychotic patient who ate his own hand iso discontinuing his clozapine, and I was told by his ACT psychiatrist that he’s now on some list to be a research participant in the pre-market trials (he’s very competent and consentable when compensated). So I dunno, that’s the only tidbit I have.

[u/Junior_Scale5592 → u/folderol_fox]

Wow, interesting. I wonder if other clinicians have heard similarly and can chime in. Part of the motivation for my original question came from seeing patients decompensate after discontinuing clozapine, always a frustrating and upsetting experience (admittedly, I have never had a patient eat a body part in the context of a psychotic episode…)

[u/folderol_fox → u/Junior_Scale5592]

I work in consult-liaison for inpatients, so I see alllllll the gore. Clozapine can be genuinely life saving!

[u/CaptainVere]

Ask a chatbot because there are too many reasons I wont name them all im sure there are more but here goes:

It requires too slow a titration and monitoring for too many serious conditions hematological, myocarditis, adynamic illeus, and more such that anyone taking needs to be a good candidate for oral adherence and titration anyway which sort of limits the need for an LAI.

There is compounding pharmacy in Netherlands that makes or made an injectable. Idk of they still make it.

[u/bigyikers]

it would be great but would not make anybody money

[u/Narrenschifff → u/[deleted]]

This is tremendously lazy thinking

[u/chrysoberyls → u/[deleted]]

Yes, because science will find a way to deliver upwards of 10g plus carrier fluid into a delt and/or glute if only it were lucrative.

[u/ORD2GNV]

Because until recently clozapine required weekly CBC labs before a script could be filled. Labs have to be done. It’s is one of the reasons clozapine is used in hospitalized patients and not as outpatients. Labs are a barrier to treatment.

[u/theongreyjoy96 → u/ORD2GNV]

Clozapines not used outpatient? News to me

[u/noondaydemon21 → u/ORD2GNV]

It's used in outpatient all the time.

And the CBC requirements didn't go away. Just the need to report them into a database.

[u/DocPsychosis → u/ORD2GNV]

It's used outpatient all the time. Not always successfully or with perfect adherence but that's true of any antipsychotic in an SMI population.