Showing posts with label Azosemide. Show all posts
Showing posts with label Azosemide. Show all posts

Sunday 14 June 2020

Summertime Autism Raging and Dumber in the Summer

By far the most read post in this blog is one about histamine and allergies, which means many people are searching on Google for “histamine, allergy and autism”.

Our reader Kei recently commented that his daughter, without allergy, was again showing signs of summertime raging and that his neurologist confirmed that summertime raging does indeed happen and nobody knows why.

I did figure out how to deal with our version of “summertime raging” and the post-bumetanide “dumber in the summer” phenomena.  There were several posts on this subject.  The lasting solution was to treat the raging as if it was caused by inflammation driven by pollen allergy and to note that inflammation will further worsen the KCC2/NKCC1 imbalance in Bumetanide-responsive autism, making those people appear “dumber in the summer”.  This also accounts for the “Bumetanide has stopped working” phenomenon, reported by some parents.  You need to minimize inflammation from allergy and increase Bumetanide (or add Azosemide).  My discovery was that Verapamil was actually more effective than anti-histamines and actual mast cell stabilizers. Mast cells degranulate via a process dependent of the L-type calcium channels that Verapamil blocks. Mast cells release histamine and inflammatory cytokines like IL-6.

This spring when Monty’s brother asked why Monty was acting dumber, it was time to implement the “dumber in the summer” therapies.  Add a morning tablet of cetirizine (Zyrtec) and a nasal spray of Dymista (Azelastine + Fluticasone).

Dymista is inexpensive and OTC where we live, but I see in the US it is quite an expensive prescription drug.  It is a favourite of Monty’s pediatrician and his ENT doctor. 

Summertime Regression in the Research Literature

I recently came across two very relevant papers on this subject by a proactive American immunologist called Dr Marvin Boris.  If you live in New York, he looks like a useful person to know.

In his first study he investigated whether the onset of the allergy season caused a deterioration in behavior of children with autism or ADHD; in more than half of the trial subjects, it did.

In his second study he went on to make a double‐blind crossover study with nasal inhalation of a pollen extract or placebo on alternate weeks during the winter.  This was his way to recreate the pollen season during winter.

Sixteen of 29 (55%) children with ASD and 12 of 18 (67%) children with ADHD or a total of 28 of 47 (60%) children regressed significantly from their baseline. Nasal pollen challenge produced significant neurobehavioral regression in these children. This regression occurred in both allergic and non‐allergic children and was not associated with respiratory symptoms.

In other words, half of children with autism regress when exposed to pollen, even though they may not show any symptoms of allergy, or test positive for allergy.  This should be of interest to Kei and his neurologist.

Purpose: To determine whether children with autistic spectrum disorders (ASD) or attention deficit hyperactive disorder (ADHD) exhibit neurobehavioral regressive changes during pollen seasons.
Design: A behavioral questionnaire‐based survey, with results matched to pollen counts; an uncontrolled, open non‐intervention study.
Materials and Methods: Twenty‐nine children identified with ASD and 18 children with ADHD comprised the study population. The parents of the study children completed the Allergic Symptom Screen for 2 weeks during the winter prior to the pollen allergy season under investigation. The parents of the ASD children also completed the Aberrant Behavior Checklist and the parents of the ADHD children completed Conners' Revised Parent Short Form for the same periods. The parents completed the respective forms weekly from 1 March to 31 October 2002. Pollen counts from the geographical area of study were recorded on a daily basis during this period.
Results: During natural pollen exposure, 15 of 29 (52%) children with ASD and 10 of 18 (56%) children with ADHD demonstrated neurobehavioral regression. There was no correlation with the child's allergic status (IgE, skin tests and RAST) or allergy symptoms.
Conclusions: Pollen exposure can produce neurobehavioral regression in the majority of children with ASD or ADHD on a non‐IgE‐mediated mechanism. Psychological dysfunction can be potentiated by environmental exposures. 

Pollen Exposure as a Cause for the Deterioration of Neurobehavioral Function in Children with Autism and Attention Deficit Hyperactive Disorder: Nasal Pollen Challenge 

Purpose: In a previous study it was established that children with attention deficit hyperactive disorder (ADHD) and autistic spectrum disorders (ASD) had regressed during pollen seasons. The purpose of this study was to determine if these children regressed on direct nasal pollen challenge. 

Design: A double‐blind crossover placebo‐controlled nasal challenge study. Materials and Methods: Twenty‐nine children with ASD and 18 with ADHD comprised the population. The study was a double‐blind crossover with nasal instillation of a pollen extract or placebo on alternate weeks during the winter. The pollens used were oak tree, timothy grass and ragweed. The dose insufflated into each nostril was 25 mg (±15%) of each pollen. 

Results: Sixteen of 29 (55%) children with ASD and 12 of 18 (67%) children with ADHD or a total of 28 of 47 (60%) children regressed significantly from their baseline. 

Nasal pollen challenge produced significant neurobehavioral regression in these children. This regression occurred in both allergic and non‐allergic children and was not associated with respiratory symptoms. There was no correlation to the child's IgE level, positive RAST pollen tests, or skin tests.


When I was figuring out Monty’s summertime raging and cognitive decline, several years ago, there were no significant signs of allergy present.  Nowadays there are far more visible signs of allergy.

Dr Boris does not suggest any therapy for summertime raging, but he did show that it can be driven by pollen in half of those with autism, even children who have no signs of having any allergy.

His studies were published more than a decade ago and seem to have been forgotten.  This seems a pity, but it says a lot.

I only stumbled upon his papers because I was reading another of his decade old papers.  That paper is based on his early use of Pioglitazone in autism, which resulted in several hundred children being successfully prescribed this drug.  Pioglitazone selectively stimulates the peroxisome proliferator-activated receptor gamma (PPAR-γ) and to a lesser extent PPAR-α.

There was a bladder cancer scare, lots of hungry lawyers and I suppose people stopped prescribing Pioglitazone for autism a decade ago.  The numerous subsequent safety studies and meta-analysis show either a small increased risk, or no increased risk, very much dependent on who financed the research.  Pioglitazone is given to people with type 2 diabetes, and they are already at an increased risk of bladder cancer.  In those people, that risk increases between 0 and about 20%, depending on the study.  We are talking about 0.07% to 0.1% of people with T2 diabetes taking Pioglitazone later developing bladder cancer.

A decade later and Pioglitazone is again back in fashion with trials in humans with autism and studies in mouse models of autism. The current autism research does not see cancer risk as reason not to use Pioglitazone.  I agree with them. 

It looks like a minority of people taking Pioglitazone are more likely to suffer upper respiratory tract infections.  That is the risk that I consider relevant.  I also note that in trials even the placebo can appear to cause upper respiratory tract infections.

Pioglitazone was covered in earlier posts, 

but there will soon be a new post.  For most people I think histamine, allergy and summertime raging will continue to be of more interest.

Thursday 22 August 2019

Bumetanide 5mg for Parkinson’s Disease?

I have been asked twice about off-label therapies for Parkinson’s, both times I mentioned Bumetanide, but having rechecked the literature, there is now plenty of supporting data, enough that a clinical trial has now been put in motion in France.

Parkinson’s disease is all about a lack of dopamine and bumetanide is all about making GABA work as inhibitory. You might wonder why is Peter suggesting people to talk to their doctor about giving their elderly parents a diuretic. Well the lack of dopamine goes on to cause a GABA dysfunction, which is treatable and does improve the symptoms of Parkinson’s.

So, Bumetanide will not cure Parkinson’s, but may reduce its severity.

In the case of the last person who asked me, her mother already takes a diuretic for other reasons, so all she would have to do is to switch drugs to Bumetanide. The doctor was only too happy, when given the evidence, to switch her to Bumetanide - a rare victory for common sense. 

What caught my attention was the dosage of Bumetanide used in the published case histories and the concern about polyuria. Polyuria is too much urination. The dose used was 5mg taken all in one go and that is a lot; you would have to run to the bathroom, which might cause falls in people with poor balance.

Since we recently discovered that Azosemide has the same effect on GABA as Bumetanide, but can have a less urgent effect as a diuretic, it may be that Azosemide is a better choice for Grandma with Parkinson’s.  Incontinence can be a feature of Parkinson’s disease.  The ideal drug will be the new one being developed by Neurochloré for autism.

Standard Parkinson’s Drugs

Since most symptoms of Parkinson’s disease (PD) are caused by a lack of dopamine in the brain, many PD drugs are aimed at either temporarily replenishing dopamine or mimicking the action of dopamine. These types of drugs are called dopaminergic medications. They generally help reduce muscle rigidity, improve speed and coordination of movement and lessen tremor.

L-DOPA, the standard treatment for Parkinson’s is actually also used in some people with autism, in particular people with Angelman Syndrome, although it failed in a clinical trial.

Bumetanide for Parkinson’s?

The clinical trial for Parkinson’s will use the standard rating scale (UPDRS) that is very much centered on motor skills. There is a tiny part on memory.

Cognition is affected in Parkinson’s and this might be another area that improves with Bumetanide; but someone has to bother to measure it.

Nobody has measured the effect of Bumetanide on IQ in those with autism, even though the effect can be substantial.


Four patients suffering from idiopathic PD at the stage of motor fluctuation were included. All of them gave their written informed consent to receive open-label bumetanide. Bumetanide was progressively titrated up to 3 mg/d (once daily) received for a month. After having verified the good tolerability of the treatment, bumetanide was increased to 5 mg/d (once daily) and received for another month. Bumetanide was added to the patient's usual antiparkinsonian treatment that was maintained stable the month before and unchanged during the study. The patients were assessed before and at 1 and 2 months after the initiation of bumetanide.
At each visit, the patient was asked about any side effects having occurred since the last visit. A Unified Parkinson's Disease Rating Scale (UPDRS)19 was performed before and after 2 months of treatment in a practical OFF stage (the patients came in the afternoon, having not taken antiparkinsonian drugs for 4 hours, and confirmed to be in an OFF stage). At the end of the study, the patient was also asked to give a global impression of change compared with baseline.

Case 3

The patient was a 58-year-old man with a 21-year history of
PD. After early development of disabling motor fluctuation and dyskinesia despite an optimized drug treatment, bilateral subthalamic electrodes were implanted 16 years ago for continuous deep brain stimulation (DBS). He got an excellent control of PD motor symptoms. However, after a year of DBS treatment, he started to develop freezing of gait and dysarthria. Despite many attempts of adjusting the treatment (DBS parameters, changes in drug treatment, and physiotherapy), these symptoms remained disabling and even slowly worsened with time. Motor fluctuation and dyskinesia were well controlled by both DBS (left side: case positive, electrode 2 negative, voltage 3.5 V; right side: case positive, electrode 1 negative, voltage 3 V; for both sides: pulse width 60 microseconds, frequency 100 Hz) and drug treatment. The latter consisted of L-DOPA, 1000 mg/d (5 intakes per day); ropinirole, 2 mg/d; and amantadine, 200 mg/d. The freezing of gait was highly disabling.

At home, the patient could walk a few steps alone with a high risk of falls. Most of the time, he was wheelchair bound. After a few days of bumetanide at a dosage of 5 mg/d, the gait dramatically improved. He was able to walk almost 1000 m without any help.

The voice was unchanged. The UPDRS III in the OFF stage was hardly changed (10% improvement), and the UPDRS II in the worst state improved by 15%. The UPDRS II in the best condition was unchanged (21 to 18). The patient and the caregiver assessed the general improvement at 50%. Despite the polyuria and the fatigue, he has decided to continue the bumetanide treatment.
After a few weeks, the improvement of gait was less dramatic but still noticeable.

GABAergic inhibition in dual-transmission cholinergic and GABAergic striatal interneurons is abolished in Parkinson disease 

We report that half striatal cholinergic interneurons are dual transmitter cholinergic and GABAergic interneurons (CGINs) expressing ChAT, GAD65, Lhx7, and Lhx6 mRNAs, labeled with GAD and VGAT, generating monosynaptic dual cholinergic/GABAergic currents and an inhibitory pause response. Dopamine deprivation increases CGINs ongoing activity and abolishes GABAergic inhibition including the cortico-striatal pause because of high [Cl]i levels. Dopamine deprivation also dramatically increases CGINs dendritic arbors and monosynaptic interconnections probability, suggesting the formation of a dense CGINs network. The NKCC1 chloride importer antagonist bumetanide, which reduces [Cl]ilevels, restores GABAergic inhibition, the cortico-striatal pause-rebound response, and attenuates motor effects of dopamine deprivation. Therefore, most of the striatal cholinergic excitatory drive is balanced by a concomitant powerful GABAergic inhibition that is impaired by dopamine deprivation. The attenuation by bumetanide of cardinal features of Parkinson’s disease paves the way to a novel therapeutic strategy based on a restoration of low [Cl]i levels and GABAergic inhibition.

Official Title:
A Randomized Double-blind Placebo-controlled Multicenter Proof-of-concept Trial to Assess the Efficacy and Safety of Bumetanide in Parkinson's Disease
Actual Study Start Date  :
April 26, 2019
Estimated Primary Completion Date  :
September 2020
Estimated Study Completion Date  :
August 2021


There is now a long list of neurological conditions that may respond to bumetanide:-

·        Autism
·        Fragile-X Syndrome
·        Down Syndrome
·        Schizophrenia
·        Huntington’s Disease
·        Parkinson’s Disease

In addition, it is obvious that some epilepsy will respond to Bumetanide. The original epilepsy drug from 150 years ago, KBr, has the same mechanism of action, lowering chloride within neurons.

Perhaps higher doses of Bumetanide need to be trialled in autism, 5mg all at once is far higher than what has been used so far in studies.

Thursday 18 July 2019

Azosemide in Autism – ça marche aussi / it works too

Rathaus/City Hall in Hanover, Germany      
Attribution: Thomas Wolf,

The short version of this post is that the old German diuretic Azosemide delivers the same autism benefit as the popular diuretic Bumetanide, but it has a different profile of diuresis.  Azosemide may indeed be more potent at blocking NKCC1 in the brain, but this needs to be investigated/confirmed.  For some people Azosemide will be a better choice than Bumetanide.

The bulk of today’s post is really likely to be of interest only to bumetanide users and the French and German bumetanide researchers.

I did suggest recently when I published version 5 of Monty’s PolyPill, that it is getting close to the final version.  Some of the potential remaining elements have already been written about in this blog, but I have not finished evaluating them.  Azosemide falls into this category.

One theme within this blog has been to increase the “autism effect” of Bumetanide, which was the first pharmaceutical intervention going back to 2012.  I did look at modifying how the body excretes Bumetanide to increase its plasma concentration using an OAT3 inhibitor, but that is little different to just increasing the dose. There are other ways to lower chloride levels within neurons than blocking NKCC1, you can target the AE3 exchanger for example with another diuretic called Diamox, or you can just substitute bromide ions for chloride ions, using potassium bromide. Bromide is used to treat Dravet Syndrome and other hard to treat types of pediatric epilepsy.

Researchers in Germany have developed modified versions (prodrugs) of Bumetanide that better cross the blood brain barrier; one interesting example is called BUM5.  Prodrugs are out of favour because they are hard to control, meaning that they work differently in different people.

The researchers in Hanover, Germany also published data showing that an old German diuretic called Azosemide might be much more potent than bumetanide inside the brain.

This becomes even more interesting because, not-surprisingly, diuretics as drugs are produced based on their diuretic effect.  The diuresis comes from their effect on a transporter called NKCC2, but the autism effect comes from blocking the very similar transporter NKCC1 in the brain. Because Azosemide and indeed Furosemide are 40 times weaker than Bumetanide at blocking NKCC2, the pills are made as Bumetanide 1mg, but Furosemide 40mg. Azosemide is now only used in parts of Asia, where people tend to be smaller and so there are 30mg tablets (the equivalent of Bumetanide 2mg is Azosemide 60mg in smaller adults).

Then comes bio-availability, which is how much of the pill you swallow makes it into your bloodstream. Bumetanide is very well absorbed, but in the case of Azosemide it can be 20%. I was informed that you can increase this 20% by taking it with Ascorbic acid, otherwise known as vitamin C.  

In the test tube, Azosemide is 4 times more potent at blocking NKCC1 than bumetanide at the same dose.

In the test tube 60 mg of Azosemide should be very much more potent than 2mg of Bumetanide at blocking the NKCC1 transporter found in the brain.

But then we do have the blood brain barrier that seems to block 99% of bumetanide form getting through. Azosemide will also struggle to cross the blood brain barrier (BBB). The Germans think that Bumetanide is much more acidic than Azosemide and that suggests that Azosemide might be more able to cross the BBB; however the French disagree.

The conclusion of all that is to take Azosemide with orange juice.

French Researchers

You might think the French researchers at Neurochloré would have trialed Azosemide before spending millions of dollars/euros approving Bumetanide for autism.  Their patent covers all these drugs, but they would find monetizing their idea much easier with Azosemide. Bumetanide is a cheap generic drug widely available across the world. Azosemide is currently only available in some parts of Asia.

I did ask the researchers a while back if anyone had tried Azosemide for autism. The answer was no.

I think the main plan all along was to develop a more potent drug than bumetanide, without diuresis, that could be used in many neurological disorders that feature disturbed chloride levels.  The licensing of Bumetanide for autism is just an intermediate step.

There are many considerations in developing the new drug, not least what exactly is bumetanide’s mode of action. Is it the central effect of the tiny 1% that can cross the blood brain barrier? Or is it a peripheral effect?

While the German researchers think Azosemide can cross the blood brain barrier better than Bumetanide, the French do not think so.

The fact that Azosemide does have the same “autism effect” as bumetanide may help understand how it works and then this would help develop the new tailor-made drug. This is why they were interested by the news in today’s post.

I did suggest making an experiment of bumetanide and Azosemide in healthy adults to measure how much is present in spinal fluid, this is a proxy for how much is inside the brain.

In the meantime bumetanide-responders with autism have the choice of two drugs, with quite different patterns of diuresis. So for one person Bumetanide might be best, in another Azosemide and in some a combination of both drugs might be best.

Bumetanide is short-acting and causes diuresis in the first 30-90 minutes, in most people it is substantial diuresis while in some people it is minimal. Azosemide is a long-acting diuretic and the peak effect is 3 to 5 hours after taking the drug. It seems that in some people the diuretic effect is very mild and it is always delayed.
When I took Azosemide to check the effect, I did not notice any diuretic effect.  I would not have known it was a diuretic.

The higher the dose of Bumetanide/Azosemide the greater the autism benefit will be, depending on how elevated the initial chloride level was. The limiting factor is diuresis and at extreme levels ototoxicity. Very high doses of loop diuretics can damage your ears – ototoxicity.

In immature neurons you have almost exclusively NKCC1 (green above) whereas in adult neurons you have almost exclusively KCC2 (orange above), but you can be at any point in between. Also this point is not fixed in one person; external factors can shift it in either direction.

As a result the effective dose of Bumetanide/Azosemide will vary from person to person AND vary over time.

The severity of diuresis limits the dosage. This is why Azosemide clearly has a role to play at least for some people.

Here is the German paper that prompted the interest in Azosemide:-

Azosemide was the most potent NKCC1 inhibitor (IC50s 0.246 µM for hNKCC1A and 0.197 µM for NKCC1B), being about 4-times more potent than bumetanide. 

Azosemide was the most potent inhibitor of hNKCC1, inhibiting both splice variants with about the same efficacy. Azosemide lacks the carboxylic group of the 5-sulfamoylbenzoic acid derivatives (Fig. 1), demonstrating that this carboxylic group is not needed for potent inhibition of NKCC1. Clinically, Azosemide has about the same diuretic potency as furosemide, but both drugs are clearly less potent than bumetanide30, so the high potency of Azosemide to inhibit the hNKCC1 splice variants was unexpected. In contrast to the short-acting diuretic bumetanide, the long-acting Azosemide is not a carboxylic acid, so that its tissue distribution should not be restricted by a high ionization rate. However, it is highly bound to plasma proteins31, which might limit its penetration into the brain. Indeed, in a study in which the tissue distribution of Azosemide was determined 30 min following i.v. administration of 20 mg/kg in rats, brain levels were below detection limits (0.05 µg/g32).

In conclusion, the main findings of the present study on structure-activity analyses of 10 chemically diverse diuretics are that (1) none of the examined compounds were significantly more effective to inhibit NKCC1B than NKCC1A, and (2) Azosemide was more potent than any other diuretic, including bumetanide, to inhibit the two NKCC1 variants. The latter finding is particularly interesting because, in contrast to bumetanide, which is a relatively strong acid (pKa = 3.6), Azosemide is not acidic (pKa = 7.38), which should avour its tissue distribution by passive diffusion. Lipophilicity (logP) of the two drugs is in the same range (2.38 for Azosemide vs. 2.7 for bumetanide). Furthermore, Azosemide has a longer duration of action than bumetanide, which results in superior clinical efficacy26 and may be an important advantage for treatment of brain diseases with abnormal cellular chloride homeostasis.

Bumetanide in use

In 2012 I started bumetanide use at 1mg once a day and after 10 day saw a positive effect. Later I tried 0.5mg twice a day and felt the effect was much reduced.  This is not really a surprise and is highly relevant.

In the later years I increased the dose to 2mg once a day initially to combat the summertime loss of effect due to allergy (inflammation) shifting the balance of NKKC1/KCC2 further towards NKCC1.

Adding a second daily dose of 1mg produced more diuresis but no noticeable benefit. I did not try a second daily dose of 2mg because I did not want yet more diuresis.

Azosemide in use

Azosemide is a so-called long acting diuretic, whereas as Bumetanide is short acting. In practise this means there is no immediate diuresis soon after taking the drug, the diuresis comes later and can be much less. The diuretic response seems to vary widely between people.

The milder diuretic effect is attractive for the second daily dose.

After 6 years the early morning diuresis has become a normal process, but once a day is really enough. So my initial trial was Azosemide in the afternoon, while retaining bumetanide in the morning.

After a week or so there were clear signs that benefits initially enjoyed from Bumetanide have been further extended.  This is exactly as the German research suggested might occur.

After a few weeks of 2mg Bumetanide at 7am and 60mg Azosemide at 4pm I moved on to Azosemide 60mg twice a day.

Is Azosemide 60 mg more potent than Bumetanide 2mg?  It is early days, but quite possibly it is.

Bumetanide is very cheap and we have got used to the early morning diuresis, so I am less bothered with the 7am drug.

After a few years drinking a lot of water, to compensate for the diuresis of bumetanide, has become a habit. So switching from Bumetanide to Azosemide does not stop diuresis, just the urgency.

In future-users going straight to Azosemide might be a good choice.

In our case it means that a potent second daily dose is a very practical option.

Anecdotal changes include:-

Very appropriate use of bad language while driving. We live in a country with some aggressive drivers and Monty hears many people’s verbal responses to this.  Now Monty makes the comments for us.  Everyone noticed and big brother was particularly impressed.

“Car’s coming!” while extracting my car from being boxed in by three other cars in a car park, Monty noticed another car coming towards us. For the first time ever Monty has given me a loud verbal warning of danger.  He has since repeated this.  I have long wondered how a person with severe autism can ever safely drive a car, because they lack situational awareness. Many people with severe autism never learn to safely cross a road on foot.

Monty improved use of his second language. He is declining nouns and translating out loud captions and phrases he sees in cartoons.

One area I hoped would improve was at the dentist. Back in March, before the summer allergy season, we had excellent behaviour at the dentist. This gradually changed and the dentist noted this.  We are slowing repairing 2 teeth without removing the nerves and this requires visits every 7 weeks to gradually remove the decay and grow a new layer of dentine above the nerve. After Azosemide the recent anxiety disappeared and Monty’s behaviour at the dentist went back to being very cheerful and entirely cooperative.  

How to access Azosemide tablets

Thanks to our doctor reader Rene, we know that you can order Japanese drugs in specialist “international pharmacies” in Germany with a valid prescription from any European country.

So all you need is a prescription and the money.

Azosemide is available in Japan as a branded product DIART and as a cheaper generic sold as Azosemide.

The price does vary on which pharmacy you approach in Germany, one pharmacy offers these prices:-

100 Tablets   ~ 74€
           500 Tablets   ~ 286€
         1000 Tablets  ~ 524€

This is much more expensive than generic Bumetanide, but less expensive than many supplements people are buying.

If you live in North America you would have to find a different method, or take a trip to Germany.


Azosemide is still “under investigation”, but the prospects look good.

As with Bumetanide, it was approved as a drug a few decades ago and so there is a great deal of safety information. It is not an experimental drug; we are just looking at repurposing it for autism and other neurological conditions with elevated chloride.

Azosemide for autism is a good example of parent cooperation and self-help. Several parents have helped in this step forward for autism treatment.

More work has to be done to see how others respond and what the most effective dosage is.

I suspect that the optimal treatment will be twice a day and the lack of substantial diuresis in most people makes it more practical than Bumetanide twice a day.  Combining Bumetanide, a short acting diuretic, with Azosemide, a long acting diuretic, is also an option to explore.

The potential risk factors are the same as Bumetanide, disturbed electrolytes, dehydration and at very high doses ototoxicity. Ototoxicity is damage to your ear that can be caused by drugs that include diuretics at very large doses.

Azosemide would appear to have milder side effects than Bumetanide.

Tuesday 14 May 2019

Making best use of existing NKCC1/2 Blockers in Autism

Azosemide C12H11ClN6O2S2  

Today’s post may be of interest to those already using bumetanide for autism and for those considering doing so.  It does go into the details, because they really do matter and does assume some prior knowledge from earlier posts.

There has been a very thorough new paper published by a group at Johns Hopkins:-
It does cover all the usual issues and raises some points that have not been covered yet in this blog.  One point is treating autism prenatally. This issue was studied twice in rats, and the recent study was sent to me by Dr Ben Ari.  Short term treatment during pregnancy produced a permanent benefit.

Maternal bumetanide treatment prevents the overgrowth in the VPA condition

Brief maternal administration of bumetanide before birth restores low neuronal intracellular chloride concentration ([Cl]i) levels, produces an excitatory-to-inhibitory shift in the action of γ-aminobutyric acid (GABA), and attenuates the severity of electrical and behavioral features of ASD (9, 10), suggesting that [Cl]i levels during birth might play an important role in the pathogenesis of ASD (7). Here, the same bumetanide treatment significantly reduced the hippocampal and neocortical volumes of P0 VPA pups, abolishing the volume increase observed during birth in the VPA condition [hippocampus: P0 VPA versus P0 VPA + BUM (P = 0.0116); neocortex: P0 VPA versus P0 VPA + BUM (P = 0.0242); KWD] (Fig. 3B). Maternal bumetanide treatment also shifted the distribution of cerebral volumes from lognormal back to normal in the population of VPA brains, restoring smaller cerebral structure volumes (Fig. 3C). It also decreased the CA3 volume to CTL level after birth, suggesting that the increased growth observed in this region could be mediated by the excitatory actions of GABA (Fig. 3D). Therefore, maternal bumetanide administration prevents the enhanced growth observed in VPA animals during birth.

One issue with Bumetanide is that it affects both:-

·        NKCC2 in your kidneys, causing diuresis
·        NKCC1 in your brain and elsewhere, which is divided into two slightly different forms NKCC1a and NKCC1b

NKCC1 is also expressed in your inner ear where it is necessary for establishing the potassium-rich endolymph that bathes part of the cochlea, an organ necessary for hearing. 

If you block NKCC1 too much you will affect hearing.

Blocking NKCC1 in children and adults is seen as safe but the paper does query what the effect on hearing might be if given prenatally as the ear is developing.

Treating Down Syndrome Prenatally

While treating autism prenatally might seem a bit unlikely, treating Down Syndrome (DS) prenatally certainly is not.  Very often DS is accurately diagnosed before birth creating a valuable treatment window.  In most countries the vast majority of DS prenatal diagnoses lead to termination, but only a small percentage of pregnancies are tested for DS. In some countries such as Ireland a significant number of DS pregnancies are not terminated, these could be treated to reduce the deficits that will otherwise inevitably follow.

The research does suggest that DS is another brain disorder that responds to bumetanide.

Back to autism and NKCC1

This should remind us that a defect in NKCC1 expression will not only cause elevated levels of chloride with in neurons, but will also affect the levels of sodium and potassium with neurons.

There are many ion channel dysfunctions (channelopathies) implicated in autism and elevated levels of sodium and potassium will affect numerous ion channels.  The paper does suggest that the benefit of bumetanide may go beyond modifying the effect of GABA, which is the beneficial mode of action put forward by Dr Ben Ari.
We have seen how hypokalemic sensory overload looks very similar to what often occurs in autism and that autistic sensory overload is reduced by taking an oral potassium supplement.

The paper also reminds us that loop diuretics like bumetanide and furosemide not only reduce inflow of chloride into neurons, but may also reduce the outflow. This is particularly known of furosemide, but also occurs with bumetanide at higher doses.
The chart below shows that the higher the concentration of bumetanide the strong its effect becomes on blocking NKCC1.

But at higher doses there will also be a counter effect of closing the NKCC2 transporter that allows chloride to leave neurons.
At some point a higher dose of bumetanide may have a detrimental effect on trying to lower chloride within neurons.

Since Dr Ben Ari’s objective is to lower chloride levels in neurons  it is important how freely these ions both enter and exit.  The net effect is what matters. (Loop diuretics block NKCC1 that lets chloride enter neurons but also block the KCC2 transporter via which they exit)

Is Bumetanide the optimal existing drug to lower chloride within neurons?  Everyone agrees that it is not, because only a tiny amount crosses into the brain. The paper gives details of the prodrugs like BUM5 that have been looked at previously in this blog; these are modified versions of bumetanide that can better slip across the blood brain barrier and then react in the brain to produce bumetanide itself.  It also highlights the recent research that suggests that Bumetanide may not be the most potent approved drug, it is quite conceivable that another old drug called Azosemide is superior.

The blood brain barrier is the problem, as is often the case.  Bumetanide has a low pH (it is acidic) which hinders its diffusion across the barrier.  Only about 1% passes through.

There is scepticism among researchers that enough bumetanide can cross into the brain to actually do any good.  This is reflected in the review paper.

The paper reminds us of the research showing how you can boost the level of bumetanide in the brain by adding Probenecid, an OAT3 inhibitor.  During World War 2 antibiotics were in short supply and so smaller doses were used, but their effect was boosted by adding Probenecid. By blocking OAT3, certain types of drug like penicillin and bumetanide are excreted at a slower rate and so the net level in blood increases.

The effect of adding Probenecid, or another less potent OAT3 inhibitors, is really no different to just increasing the dose of bumetanide.

The problem with increasing the dose of bumetanide is that via its effect on NKCC2 you cause even more diuresis, until eventually a plateau is reached.

Eventually, drugs selective for NKCC1a and/or NKCC1b will appear.

In the meantime, the prodrug BUM5 looks good. It crosses the BBB much better than bumetanide, but it still affects NKCC2 and so will cause diuresis.  But BUM5 should be better than Bumetanide + Probenecid, or a higher dose of Bumetanide.  BUM5 remains a custom-made research drug, never used in humans.

I must say that what again stands out to me is the old German drug, Azosemide.

In a study previously highlighted in this blog, we saw that Azosemide is 4 times more potent than Bumetanide at blocking NKCC1a and NKCC1b.

Azosemide is more potent than bumetanide and various other loop diuretics to inhibit the sodium-potassium-chloride-cotransporter human variants hNKCC1A and hNKCC1B

Azosemide is used in Japan, where recent research shows it is actually more effective than other diuretics

Azosemide, a Long-acting Loop Diuretic, is Superior to Furosemide in Prevention of Cardiovascular Death in Heart Failure Patients Without Beta-blockade 

As is often the case, Japanese medicine has taken a different course to Western medicine.

Years of safety information has already been accumulated on Azosemide.  It is not an untried research drug. It was brought to market in 1981 in Germany. It is available as Diart in Japan made by Sanwa Kagaku Kenkyusho and as a cheaper generic version by Choseido Pharmaceutical. In South Korea Azosemide is marketed as Uretin.

In any other sector other than medicine, somebody would have thought to check by now if Azosemide is better than Bumetanide.  It is not a matter of patents, Ben-Ari has patented all of the possible drugs, including Azosemide and of course Bumetanide.

So now we move on to Azosemide.

When researchers came to check the potency of the above drugs the results came as a surprise.  It turns out that the old German drug Azosemide is 4 times as potent as bumetanide.

The big question is how does it cross the blood brain barrier.

“The low brain concentrations of bumetanide obtained after systemic administration are thought to result from its high ionization (>99%) at physiological pH and its high plasma protein binding (>95%), which restrict brain entry by passive diffusion, as well as active efflux transport at the blood-brain barrier(BBB). The poor brain penetration of bumetanide is a likely explanation for its controversial efficacy in the treatment of brain diseases

“… azosemide was more potent than any other diuretic, including bumetanide, to inhibit the two NKCC1 variants. The latter finding is particularly interesting because, in contrast to bumetanide, which is a relatively strong acid (pKa = 3.6), azosemide is not acidic (pKa = 7.38), which should favor its tissue distribution by passive diffusion. Lipophilicity (logP) of the two drugs is in the same range (2.38 for azosemide vs. 2.7 for bumetanide). Furthermore, azosemide has a longer duration of action than bumetanide, which results in superior clinical efficacy26 and may be an important advantage for treatment of brain diseases with abnormal cellular chloride homeostasis.”

Dosage equivalents of loop Diuretics

Bumetanide has very high oral bioavailablity, meaning almost all of what you swallow as a pill makes it into your bloodstream.

Furosemide and Azosemide have much lower bioavailability and so higher doses are needed to give the same effect.

Both Furosemide and Bumetanide are short acting, while Azosemide is long acting.

For a drug that needs to cross the blood brain barrier small differences might translate into profoundly different effects.

The limiting factor in all these drugs is their effect on NKCC2 that causes diuresis.

1mg of bumetanide is equivalent to 40mg of furosemide.
2mg of bumetanide is equivalent to 80mg of furosemide.

The standard dose for Azosemide in Japan, where people are smaller than in the West, is 30 mg or 60mg. 

Research suggests that the same concentration of Azosemide is 4x more potent than Bumetanide at blocking NKCC1 transporters, other factors that matter include:-

·        How much of the oral tablet ends up in the bloodstream.
·        How long does it stay in the blood stream
·        How much of the drug actually crosses the blood brain barrier
·        How does the drug bind to the NKCC1 transporters in neurons
·        How rapidly is the drug excreted from the brain
·        What effect is there on the KCC2 transporter that controls the exit of chloride ions from neurons.

All of this comes down to which is more effective in adults with autism 2mg of bumetanide or 60mg of Azosemide.

The side effects, which are mainly diuresis and loss of electrolytes will be similar, but Azosemide is a longer acting drug and so there will be differences. In fact Azosemide is claimed to be less troublesome than Bumetanide in lower potassium levels in your blood.


The open question is whether generic Azosemide is “better” than generic Bumetanide for treating brain disorders in humans.

I did recently ask Dr Ben-Ari if he is aware of any data on this subject. There is none.

Many millions of dollars/euros are being spent getting Bumetanide approved for autism, so it would be a pity if Azosemide turns out to be better. (Dr Ben Ari’s company Neurochlore wants to develop a new molecule that will cross the blood brain barrier, block NKCC1 and not NKCC2 and so will not cause diuresis).

The hunch of the researchers from Hanover, Germany seems to be that the old German drug Azosemide will be better than Bumetanide.

I wonder if doctors at Johns Hopkins / Kennedy Krieger have started to prescribe bumetanide off-label to their patients with autism.  Their paper shows that they have a very comprehensive knowledge of the subject.


I suggest readers consult the full version of the Johns Hopkins review paper on Bumetanide, it is peppered with links to all the relevant papers.

Bumetanide (BTN or BUM) is a FDA-approved potent loop diuretic (LD) that acts by antagonizing sodium-potassium-chloride (Na-K-Cl) cotransporters, NKCC1 (SLc12a2) and NKCC2. While NKCC1 is expressed both in the CNS and in systemic organs, NKCC2 is kidney-specific. The off-label use of BTN to modulate neuronal transmembrane Clgradients by blocking NKCC1 in the CNS has now been tested as an anti-seizure agent and as an intervention for neurological disorders in pre-clinical studies with varying results. BTN safety and efficacy for its off-label use has also been tested in several clinical trials for neonates, children, adolescents, and adults. It failed to meet efficacy criteria for hypoxic-ischemic encephalopathy (HIE) neonatal seizures. In contrast, positive outcomes in temporal lobe epilepsy (TLE), autism, and schizophrenia trials have been attributed to BTN in studies evaluating its off-label use. NKCC1 is an electroneutral neuronal Climporter and the dominance of NKCC1 function has been proposed as the common pathology for HIE seizures, TLE, autism, and schizophrenia. Therefore, the use of BTN to antagonize neuronal NKCC1 with the goal to lower internal Cl levels and promote GABAergic mediated hyperpolarization has been proposed. In this review, we summarize the data and results for pre-clinical and clinical studies that have tested off-label BTN interventions and report variable outcomes. We also compare the data underlying the developmental expression profile of NKCC1 and KCC2, highlight the limitations of BTN’s brain-availability and consider its actions on non-neuronal cells.

Btn Pro-Drugs and Analogs

To improve BTN accessibility to the brain, pro-drugs with lipophilic and uncharged esters, alcohol and amide analogs have been created. These pro-drugs convert to BTN after gaining access into the brain. There was a significantly higher concentration of ester prodrug, BUM5 (N,N – dimethylaminoethyl ester), in mouse brains compared to the parent BTN (10 mg/kg, IV of BTN and equimolar dose of 13 mg/kg, IV of BUM5) (Töllner et al., 2014). BUM5 stopped seizures in adult animal models where BTN failed to work (Töllner et al., 2014Erker et al., 2016). BUM5 was also less diuretic and showed better brain access when compared to the other prodrugs, BUM1 (ester prodrug), BUM7 (alcohol prodrug) and BUM10 (amide prodrug). BUM5 was reported to be more effective than BTN in altering seizure thresholds in epileptic animals post-SE and post-kindling (Töllner et al., 2014). Furthermore, BUM5 (13 mg/kg, IV) was more efficacious than BTN (10 mg/kg, IV) in promoting the anti-seizure effects of PB, in a maximal electroshock seizure model (Erker et al., 2016). Compared to BUM5 which was an efficacious adjunct to PB in the above mentioned study, BTN was not efficacious when administered as an adjunct (Erker et al., 2016). In addition to seizure thresholds, further studies need to be conducted to assess effects of BUM5 on seizure burdens, ictal events, duration and latencies.
Recently, a benzylamine derivative, bumepamine, has been investigated in pre-clinical models. Since benzylamine derivatives lack the carboxylic group of BTN, it results in lower diuretic activity (Nielsen and Feit, 1978). This prompted Brandt et al. (2018) to explore the proposed lower diuretic activity, higher lipophilicity and lower ionization rate of bumepamine at physiological pH. Since it is known that rodents metabolize BTN quicker than humans, the study used higher doses of 10 mg/kg of bumepamine similar to their previous BTN studies (Olsen, 1977Brandt et al., 2010Töllner et al., 2014). Bumepamine, while only being nominally metabolized to BTN, was more effective than BTN to support anticonvulsant effects of PB in rodent models of epilepsy. This GABAergic response, however, was not due to antagonistic actions on NKCC1; suggesting bumepamine may have an off-target effect, which remains unknown. However, the anticonvulsive effects of bumepamine, in spite of its lack of action on NKCC1, are to be noted. Additionally, in another study by the same group, it was shown that azosemide was 4-times more potent an inhibitor of NKCC1 than BTN, opening additional avenues for better BBB penetration and NKCC1-antagonizing compounds for potential neurological drug discovery (Hampel et al., 2018).


The beneficial effects of BTN reported in cases of autism, schizophrenia and TLE, given its poor-brain bioavailability are intriguing. The mechanisms underlying the effects of BTN, as a neuromodulator for developmental and neuropsychiatric disorders could be multifactorial due to prominent NKCC1 function at neuronal and non-neuronal sites within the CNS. Investigation of the possible off-target and systemic effects of BTN may help further this understanding with the advent of a new generation of brain-accessible BTN analogs.