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Showing posts with label Bumetanide. Show all posts
Showing posts with label Bumetanide. Show all posts

Monday 10 June 2019

The Safe Use of Bumetanide in Children with Autism



Today's post is Agnieszka's new guide to the safe use of bumetanide as an autism therapy in children.

Since most people actually read this blog on their smart phone, the document is repeated below and it will be much easier to read on a smartphone in the blog format, rather than the PDF document, because your phone should adjust the formatting. 

It is clear that most people treating autism are using Facebook and a smartphone. I am doing it with a big computer monitor and twenty windows open, each with a different scientific paper.  In the end all that matters is the result.


Practical Tips for Parents and Professionals

Agnieszka Wroczyńska MD, PhD 1, Peter Lloyd-Thomas MEng, MBA2  

1. Medical University of Gdańsk, Poland
wroczynska@gumed.edu.pl

Updated: 06.06.2019

Bumetanide is a prescription diuretic drug usually used to treat heart diseases or hypertension in adults. It also affects neuronal chloride regulation and was found to improve the quality of life of autistic children targeting core autism symptoms in clinical trials in Europe. Bumetanide has been used off-label in children and adults across the autism spectrum for several years, mostly in France. It is a safe drug with a long history of use in medicine and well-known precautions ensure side effects are avoided.
Details of bumetanide’s mechanism of action and its beneficial effects in autism were discussed elsewhere – see the references below. According to the most recent review of bumetanide clinical trials in autism:
"Current evidence suggests bumetanide, with close monitoring, may be useful in patients with moderate to severe ASD when traditional behavioral therapies are not available or an irritability-modifying pharmacological agent is not required” [James et al. 2019].

#1 Myth: Bumetanide is an experimental drug.
No. Bumetanide has been used in medicine for years. It’s safety profile and recommended precautions are well known and understood. Bumetanide has been studied in both adults and children and found to be well tolerated.
Bumetanide treatment should be supervised by a physician. Multinational phase 3 trial of bumetanide for children with autism aged 2-17 years of age started in Europe in 2018. If you live elsewhere and consider bumetanide, this article can be used as a practical companion to ensure safe treatment. It is written for parents and physicians who are not experienced with diuretic use in children or bumetanide itself. While bumetanide’s safety precautions can be summarized in short as “drinking more water, eating bananas and if required, use potassium supplementation”, this document aims to explain those in detail and provide practical tips for a variety of clinical scenarios.
Who can use bumetanide? What should you do before starting bumetanide?
If you are considering using bumetanide, make sure to check with your doctor if there are any contraindications in your child. Bumetanide is a sulfonamide drug. Children with allergy to sulfonamides should not take bumetanide. Another sulfonamide drug commonly used in children is an antibiotic called trimethoprim/ sulfamethoxazole (TMP/SMX), also known as co-trimoxazole. In many European countries co-trimoxazole’s brand name is Bactrim. If your child is allergic to co-trimoxazole (Bactrim) or any other sulfonamide drug, then bumetanide should not be used.
It is important to make a distinction between sulfonamide drugs and other sulfur-containing medications and additives, such as sulfates and sulfites, which are chemically unrelated to the sulfonamide group. Allergic reactions associated with sulfonamides are not associated with sulfur, sulfates or sulfites intolerance.
The full list of bumetanide interactions with other drugs is long, but most of the drugs included are not usually used in children.
Children with liver or kidney diseases as well as those with abnormal ECG (electrocardiogram) findings were excluded from the French bumetanide trials. If your child suffers from one of these conditions you need to discuss bumetanide safety with the relevant specialist. Epilepsy does not preclude bumetanide use. In fact, preliminary research showed bumetanide has a positive impact on seizures in temporal lobe epilepsy in adults.
What laboratory tests are needed before and during bumetanide treatment in children
Bumetanide is a safe drug, provided basic precautions related to its diuretic mechanism of action are taken. One of the most important safety considerations associated with bumetanide use is electrolyte balance. Bumetanide can affect electrolyte blood level and increase potassium loss. Extremely low potassium levels are dangerous, but this is preventable with simple measures in a person using bumetanide.


#2 Myth: Bumetanide use in children with autism is associated with significant risk of dangerous adverse effects.
No. Clinical trials and off-label prescribing experience proved that bumetanide adverse effects can be easily prevented in children. No dangerous symptoms were related to bumetanide in studies on its use in children with autism.
No serious symptoms associated with low potassium levels or electrolyte imbalance were seen in children included into bumetanide trials and case reports so far. However, they might affect a child’s well-being and possibly reduce bumetanide’s positive behavioral or sensory effect. You may not see the expected results of bumetanide treatment if an adequate potassium level and hydration are not ensured in your child.
That is why it is necessary to test electrolytes levels (potassium, sodium, chloride, magnesium and calcium) before bumetanide introduction and repeat them, especially potassium blood concentration, after the treatment is started.
In the French bumetanide trials several other blood tests were offered to children i.e.  g-glutamyltransferase, transaminases, alkaline phosphatases, glucose, uric acid and creatinine. While it is not required to order all of them in a similar way as in the research clinical studies, they are basic and cheap tests, available in most laboratories and it is prudent to check these parameters at least once during early phase of the bumetanide treatment. In clinical trials children were examined by a physician on a regular basis and had their heart rate, blood pressure and weight checked. Such approach also improves safety of bumetanide use. In turn, all these simple steps increase the chance of experiencing positive effects of bumetanide treatment. Bumetanide proved to be a safe treatment in the trials. Blood pressure and results of the routine tests did not differ between the bumetanide and placebo groups. Kidney ultrasound did not reveal any abnormalities during treatment. Children in the trials had also ECG (electrocardiogram) done as a precaution. It is prudent to offer a child such test as they are non-invasive and can be done in a stress-free manner.
As bumetanide is a diuretic drug, it is highly recommended to explain its effects prior to treatment and with the use of the communication means used by that child. Social stories, visuals and AAC tools can be helpful for some children. This approach can reduce psychological stress potentially related to the diuretic treatment in children prone to anxiety in new situations.

Fig. 1. Visuals can help a child anticipate and accept bumetanide diuretic effect prior to start of treatment.
The diuretic effect of bumetanide is strongest within the first 2 hours of taking the drug. Bumetanide given early in the morning (straight after waking up) lets the child avoid unnecessary toilet visits at school or kindergarten. Giving bumetanide once a day may be much more convenient depending on the person’s particular circumstances.
Starting bumetanide - what dose should be used and what to expect?

In the first randomized clinical trial in France the dose of 0.5 mg bumetanide was given twice daily to children 3-11 years old and was found effective in many of them. However, for some people this dose may not be sufficient as actually only about 1% of bumetanide can cross the blood brain barrier and act on neurons.  In the 2017 bumetanide study doses up to 2 mg twice daily were trialed. While using higher doses may increase the amount of bumetanide that would reach the brain and so enhance the positive effects of the treatment, it also was found that drug-related adverse event risk is dose dependent and 0.5 mg b.i.d (twice daily) dose was found to be the best tolerated. It is a matter of a careful, individual trial to find an optimal dose for each person.
The benefits of bumetanide treatment can sometimes be seen as early as after 2 weeks, but it is not uncommon to have to wait longer. It is recommended to continue up to 3 months to assess the full impact of bumetanide use. Minor effects may indicate that the child is indeed a bumetanide responder, but the dose needs to be increased.
The beneficial effects seen in a child taking bumetanide are highly variable and individual. In general, this drug targets core autism symptoms and improvements in communication, social skills, including eye contact, speech and sensory issues were reported on bumetanide, as well as stereotyped behaviors decrease, better mood or increased cognition. Many parents can notice more awareness in their children and describe it as if “the fog has lifted”. Behavioral improvements were also reported on bumetanide e.g. reduction in aggressive behaviors.
The only known indicator of which people with autism respond to bumetanide, is a previous unexpected negative reaction to Valium (diazepam), or other benzodiazepine drug.  These drugs should be calming, but in some people with the GABA neurotransmitter dysfunction targeted by bumetanide, the effect can be agitation and aggression.
How to control hydration in children using bumetanide?
Bumetanide belongs to the “loop diuretics” class of drugs which can lower blood potassium level and increase the body fluid loss. You need to monitor hydration in a child treated with bumetanide. If fluid consumption is increased to compensate for the diuresis, there will be no significant blood pressure lowering effect from bumetanide, nor will there be dehydration. The daily amount of fluid required varies, but it usually needs to be significantly higher than the volume drank by a child before bumetanide treatment.
Some children drink up to 3 liters (3 US quarts) per day while on bumetanide, others need less. It is safer to err on the side of too much fluid intake rather than too little. Drinking 3 liters of fluids a day in a teenager on bumetanide is not unusual.
In children who still wear diapers/nappies the amount of diuresis may cause a problem with leakage.


Monitoring hydration and potassium control are two key safety precautions in bumetanide use in children with autism.
No severe adverse clinical symptoms related to dehydration were found during the bumetanide pediatric trials. However, a child who develops dehydration issues on bumetanide may feel unwell, so it is highly recommended to prevent it.

An easy way to check hydration status in a child is an assessment of mouth mucosa. You can ask your child to present her or his tongue and compare the tongue look with another member of the family. It can be made a good fun for younger children. If the tongue mucosa looks drier in a child on bumetanide, then you need to help the child drink more. Most children automatically drink more fluids, but some refuse to cooperate and drink more.  Finding out beverages attractive for your child (e.g. drinking water from a dispenser, juice with ice-cubes etc.) may be useful in such a situation.

Fig. 2. Monitoring hydration may be done in a funny way to make the treatment stress-free.

Monitoring hydration with weight checks or measuring urine volume, while used in other situations, are impractical in a person on bumetanide. 
You can read more on child dehydration symptoms here. It is useful to learn about those symptoms as a parent even if you do not plan to use bumetanide.
How to ensure enough potassium intake in a child on bumetanide?
Simple dietary modifications can provide necessary additional potassium and are recommended for every child on bumetanide. Use potassium salt and increase other dietary potassium in your kitchen. Bananas, kiwis, dried fruit, tomatoes are all examples of foods rich in potassium. The daily recommended intake of potassium is 3 to 4 g depending on age. A medium sized banana contains about 0.5g. Most people do not achieve the RDA for potassium but exceed the maximum limit for sodium, which is about 2g. More on potassium food content can be found here.

#3 Myth: Potassium supplements can cause serious heart rhythm issues in children on bumetanide.
No. Recommended potassium daily intake is well above the supplement doses usually used with bumetanide. Provided normal kidney function, there is no significant risk of dietary/oral supplement potassium overdose when typically recommended doses are considered.
Apart from dietary modifications, low dose potassium supplementation can be used in addition to bumetanide from the beginning of the treatment. In the first weeks of bumetanide use it is also necessary to test potassium blood level. In the French trial blood potassium levels were checked before bumetanide introduction and then at 7, 30, 60 and 90 days after the treatment started. You may consider potassium blood level test sooner than after 30 days: it can be scheduled 2-3 weeks after bumetanide introduction to detect low potassium level early. The normal blood level range of potassium is 3,5 - 5,0 mmol/l.  In case of abnormally low blood potassium level (which is called “hypokalemia”) you need to consult your doctor and add or adjust the dose of potassium supplement for your child. The target is to keep the potassium level well within the normal range. In the first bumetanide randomized clinical trial 22% of children taking bumetanide 0.5 mg b.i.d. (twice daily) experienced benign hypokalemia (low potassium), which was resolved by giving potassium gluconate syrup. In the next French trial the potassium level fell below normal range in 30% of children on that dose, but no serious potassium-related adverse event was seen. A potassium supplement was given to all these children to correct the low blood level.
 The potassium dose should be adjusted individually according to blood level and repeat tests may be helpful. As some autistic children seem not to tolerate even minor drops in potassium level, you and your doctor may consider increasing potassium supplementation to keep its level in the upper normal range in those cases.

Side effects of bumetanide and how to manage them:
- “Accidents” caused by diuresis: need to plan ahead. Don’t give bumetanide before starting a long car journey or before sleep.
- Dehydration has many effects that you may not notice. Make sure your child carries a water bottle and so has easy access to fluids.
- Low potassium has many effects and so add potassium to diet as a precaution. Most people are nowhere near the recommended intake of potassium, so add potassium-rich food to diet.
The optimal dose of potassium varies and is highly individual: few children need dietary modifications only, some use as low as 100 mg potassium daily, while some require 500 mg t.i.d. (three times a day) to maintain normal potassium level on bumetanide. Potassium supplements come in different forms e.g. syrup, effervescent tablets, slow-release capsules. Liquid supplements, including effervescent drinks, seem free from the risk of GI distress associated with tablets, which may be especially important in a child who is not able to communicate the pain. It is very hard to do harm by eating too much dietary potassium, because it is absorbed very slowly. Many potassium supplements are absorbed quickly and so giving more than 500mg at once is unwise.  Note that in America most potassium supplement tablets do not contain more than 100mg.
It is necessary to actively prevent dehydration and potassium loss while on bumetanide treatment. The good news is that it is easy to achieve with simple steps described above. These precautions become even more important in children who struggle to report thirst and distress due to communication difficulties as well as in situations which make a child prone to dehydration regardless of diuretic use e.g. diarrhea, vomiting, fever or very hot summer temperatures, especially during physical exercise. If such issues occur, you need to be vigilant, consider a doctor’s appointment and potassium blood level check with additional supplementation as needed.
In case of persistent low blood potassium concentration it is recommended to check blood levels of magnesium as well. Magnesium deficiency may contribute to hypokalemia (low potassium). If this is the case, supplementing magnesium along with potassium is a solution. Low potassium levels can also be made worse by high sodium levels.
Is long term bumetanide use safe and practical?

#4 Myth: While on bumetanide every child is required to have often blood draws to check potassium.
No. Repeated blood draws are required at the beginning of bumetanide treatment to assess individual supplemental potassium needs. Later there is no need to test potassium on regular basis.
Over time, on a proper diet and potassium supplementation, a child treated with bumetanide usually achieves a stable electrolyte balance, so control blood tests are rarely required on long term bumetanide treatment. In fact long term bumetanide use is very practical, and the simple safety precautions required are nothing compared to coping with untreated symptoms common in severe autism e.g. sensory suffering, which may significantly improve on bumetanide.
If a blood draw is an issue in a child with anxiety or sensory disorders, this is what might help:
-          Visuals to reduce anxiety in a child e.g. picture social stories explaining blood draw procedure
-          AAC used for communication in a non-verbal or minimally verbal children
-          Video modeling or blood draw play at home before the procedure
-          Skilled nurse and friendly environment, which can be arranged in advance
-          At home blood draw service.


Fig. 3. Visuals can help with reducing the blood draw related anxiety.

It needs to be stressed that in general, presumed behavioral difficulties should not be a barrier to necessary medical examinations or procedures needed for health in autistic children, as avoiding them can result in increasing the medical risks in a population already prone to co-morbidities and poor health outcomes. It is the responsibility of the health provider and the parent to find the most convenient and effective way to perform the examinations needed. It is not unusual that all medical procedures get easier over the time in a child who uses bumetanide and develops communications skills and improves their cognitive function and awareness.
How to deal with the “bumetanide has stopped working” problem?
After some months or even years some parents may feel that “bumetanide has stopped working”, this may well not be their imagination and it can be very disconcerting. A little science is required to explain what may be happening. It appears that bumetanide responders have too many NKCC1 transporters in their neurons and too few KCC2. Only about 1% of bumetanide can cross the blood brain barrier where it blocks the NKCC1 transporter. An inflammatory response elsewhere in the body sends inflammatory signals throughout the body and some reach the brain where this causes an increase in NKCC1 and a reduction in KCC2 expression.  This effect can wipe out the beneficial effect of that tiny 1% of bumetanide that is present.  You can increase the dose of bumetanide and try and reduce the source of inflammation, which might be as simple as an allergy, or the cause might be harder to identify.  There will be many other biological reasons why a shift in NKCC1/KCC2 might occur, so some detective work will be needed.  The beneficial effect of bumetanide will then be restored. 
Conclusions
Almost all parents whose children were included into the first bumetanide randomized clinical trial in France asked for treatment continuation after the study finished. Safe use of bumetanide for up to 2 years later were reported in this group. According to personal communication, bumetanide has been successfully subsequently used off label for at least 8 years in children and youth with autism, and no long-term issues emerged on long-term treatment. While this treatment does not offer an “autism cure”, it could significantly increase the quality of life of autistic persons thanks its potential to bring about improvements in sensory processing and hypersensitivity, cognition and acquiring communication skills (see published studies, linked below, for details on potential positive effects of bumetanide).

Acknowledgements: Thanks to  Natasa Blagojevic-Stokic for language editing and comments.
Conflict of interest:  none
References:

1.       Lemonnier et al.: A randomised controlled trial of bumetanide in the treatment of autism in children. Transl Psychiatry 2012 2:e202.  https://www.ncbi.nlm.nih.gov/pubmed/23233021

2.       Lemonnier et al.: Treating Fragile X syndrome with the diuretic bumetanide: a case report. Acta Paediatr. 2013, 102(6):e288-90 http://www.ncbi.nlm.nih.gov/pubmed/23647528

3.       Grandgeorge et al.: The effect of bumetanide treatment on the sensory behaviours of a young girl with Asperger syndrome. BMJ Case Rep 2014 pii: bcr2013202092. http://www.ncbi.nlm.nih.gov/pubmed/24488662

4.       Bruining et al.: Paradoxical Benzodiazepine Response: A Rationale for Bumetanide in Neurodevelopmental Disorders? Pediatrics 2015 136(2): e539-43 http://www.ncbi.nlm.nih.gov/pubmed/26216321

5.       Lemonnier et al.: Effects of bumetanide on neurobehavioral function in children and adolescents with autism spectrum disorders. Transl Psychiatry 2017, 7(3):e1056 https://www.ncbi.nlm.nih.gov/pubmed/28291262

6.       James et al.: Bumetanide for Autism Spectrum Disorder in Children: A Review of Randomized Controlled Trials. Ann Pharmacother. 2019, 53(5):537-544 https://www.ncbi.nlm.nih.gov/pubmed/30501497

7.       Gharaylou et al.: A Preliminary Study Evaluating the Safety and Efficacy of Bumetanide, an NKCC1 Inhibitor, in Patients with Drug-Resistant Epilepsy. CNS Drugs. 2019, 33(3):283-291 https://www.ncbi.nlm.nih.gov/pubmed/30784026


Free AAC symbol source:






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.

Conclusion  

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.


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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).

Conclusion


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.