Mefenamic acid (Ponstan) for some Autism

Caution:-

Ponstan (Mefenamic Acid) contains a warning:-

Caution should be exercised when treating patients suffering from epilepsy.

At lower doses Ponstan is antiepileptic, but at high doses it can have the opposite effect.  This effect depends on the biological origin of the seizures.

In an earlier post I wrote about a paper by Knut Wittkowski who applied statistics to interpret the existing genetic data on autism. 

“Autism treatments proposed by clinical studies and human genetics are complementary” & the NSAID Ponstan as a Novel AutismTherapy

His analysis suggested the early use of Fenamate drugs could potentially reduce the neurological anomalies that develop in autism as the brain develops.  The natural question arose in the comments was to whether it is too late to use Fenamates in later life.

Knut was particularly looking at a handful of commonly affected genes (ANO 2/4/7 & KCNMA1) where defects should partially be remedied by use of fenamates.

I recently received a comment from a South African reader who finds that his children’s autism improves when he gives them Ponstan and he wondered why.  Ponstan (Mefenamic Acid) is a fenamate drug often used in many countries as a pain killer, particularly in young children.

Ponstan is a cheap NSAID-type drug very widely used in some countries and very rarely used in other countries like the US.  It is available without prescription in some English-speaking countries (try a pharmacy in New Zealand, who sell online) and, as Petra has pointed out, it is widely available in Greece.

I did some more digging and was surprised what other potentially very relevant effects Ponstan has.  Ponstan affects GABA_A receptors, where it is a positive allosteric modulator (PAM).  This may be very relevant to many people with autism because we have seen that fine-tuning the response of the sub-units that comprise GABA_A receptors you can potentially improve cognition and also modulate anxiety. 

Anxiety seems to be a core issue in Asperger’s, whereas in Classic Autism, or Strict Definition Autism (SDA) the core issue is often actually cognitive function rather than “autism” as such.

In this post I will bring together the science showing why Ponstan should indeed be helpful in some types of autism.

Professor Ritvo from UCLA read Knut’s paper and also the bumetanide research and suggested that babies could be treated with Ponstan and then, later on, with  Bumetanide.

Autism treatments proposed by clinical studies and human genetics are complementary

I do not think the professor or Knut are aware of Ponstan’s effect on GABA.

The benefits from Ponstan may very well be greater if given to babies at risk of autism, but there does seem to be potential benefit for older children and adults, depending on their type of autism.

Professor Ritvo points out that that Ponstan is safely used in 6 month old babies, so trialing it in children and adults with autism should not be troubling.

Being an NSAID, long term use at high doses may well cause GI side effects.  An open question is the dosage at which Ponstan modulates the calcium activated ion channels that are implicated in some autism and also what dosage affects GABA_A receptors.  It might well be lower than that required for Ponstan’s known ant-inflammatory effects.

Ponstan vs Ibuprofen

Ibuprofen is quite widely used in autism.  Ibuprofen is an NSAID but also a PPAR gamma agonist.  Ponstan is an NSAID but has no effect on PPAR gamma.

Research shows that some types of autism respond to PPAR gamma agonists.

So it is worth trying both Ponstan and Ibuprofen, but for somewhat different reasons.

They are both interesting to deal with autism flare-ups, which seem common.

Other drugs that people use short term, but are used long term in asthma therapy,  are Singulair (Montelukast) and an interesting Japanese drug called Ibudilast.  Singulair is a Western drug for maintenance therapy in asthma.  Ibudilast is widely used in Japan as maintenance therapy in Asthma, but works in a different way.  Ibudilast is being used in clinical trials in the US to treat Multiple Sclerosis.  Singulair is cheap and widely available, Ibudilast is more expensive and available mainly in Japan.

Pre-vaccination Immunomodulation

In spite of there being no publicly acknowledged link between vaccinations and autism secondary to mitochondrial disease (AMD), I read that short term immunomodulation is used prior to vaccination at Johns Hopkins, for some babies.

Singulair is used, as is apparently ibuprofen.  Ponstan and Ibudilast would also likely be protective.   Ponstan might well be the best choice; it lowers fevers better than ibuprofen.

For those open minded people, here is what a former head of the US National Institutes of Health, Bernadine Healy, had to say about the safe vaccination.  Not surprisingly she was another Johns Hopkins trained doctor, as is Hannah Poling’s Neurologist father.

The Vaccines-Autism War: Détente Needed

“Finally, are certain groups of people especially susceptible to side effects from vaccines, and can we identify them? Youngsters like Hannah Poling, for example, who has an underlying mitochondrial disorder and developed a sudden and dramatic case of regressive autism after receiving nine immunizations, later determined to be the precipitating factor. Other children may have a genetic predisposition to autism, a pre-existing neurological condition worsened by vaccines, or an immune system that is sent into overdrive by too many vaccines, and thus they might deserve special care. This approach challenges the notion that every child must be vaccinated for every pathogen on the government's schedule with almost no exception, a policy that means some will be sacrificed so the vast majority benefit.”

So if I was an American running the FDA/CDC I would suggest giving parents the option of paying a couple of dollars for 10 days of Ponstan prior to these megadose vaccinations and a few days afterwards.  No harm or good done in 99.9% of cases, but maybe some good done for the remainder.

The fact the fact that nobody paid any attention to the late Dr Healy on this subject tells you a lot.

Fenamates (ANO 2/4/7 & KCNMA1)

Here Knut is trying to target the ion channels expressed by the genes ANO 2/4/7 & KCNMA1. 

·        ANO 2/4/7 are calcium activated chloride channels. (CACCs)

·        KCNMA1 is a calcium activated potassium channel.  KCNMA1encodes the ion channel K_Ca1.1, otherwise known as BK (big potassium).  This was the subject of post that I never got round to publishing.

  

Fenamates are an important group of clinically used non-steroidal anti-inflammatory drugs (NSAIDs), but they have other effects beyond being anti-inflammatory.  They act as CaCC inhibitors and also stimulate BKCa channel activity.

But fenamates also have a potent effect on what seems to be the most dysfunctional receptor in classic autism, the GABAA receptor.

Characterization of the interaction between fenamates and hippocampal neuron GABAA receptors

The fenamate NSAID, mefenamic acid (MFA) prevents convulsions and protects rats from seizure-induced forebrain damage evoked by pilocarpine (Ikonomidou-Turski et al., 1988) and is anti-epileptogenic against pentylenetetrazol (PTZ)-induced seizure activity, but at high doses induces seizures (Wallenstein, 1991). In humans, MFA overdose can lead to convulsions and coma (Balali-Mood et al, 1981; Young et al., 1979; Smolinske et al., 1990). More recent data by Chen and colleagues (1998) have shown that the fenamates, flufenamic, meclofenamic and mefenamic acid, protect chick embryo retinal neurons against ischaemic and excitotoxic (kainate and NMDA) induced neuronal cell death in vitro (Chen et al., 1998a; 1998b). MFA has also been reported to reduce neuronal damage induced by intraventricular amyloid beta peptide (Aβ1-42) and improve learning in rats treated with Aβ1-42 (Joo et al., 2006). The mechanisms underlying these anti-epileptic and neuroprotective effects are not well understood but together suggest that fenamates may influence neuronal excitability through modulation of ligand and/or voltage-gated ion channels. In the present study, therefore, we have investigated this hypothesis by determining the actions of five representative fenamate NSAIDs at the major excitatory and inhibitory ligand-gated ion channels in cultured hippocampal neurons

This study demonstrates for the first time that mefenamic acid and 4 other representatives of the fenamate NSAIDs are highly effective and potent modulators of native hippocampal neuron GABAA receptors. MFA was the most potent and at concentrations equal to or greater than 10 μM was also able to directly activate the GABAA gated chloride channel. A previous study from this laboratory reported that mefenamic acid potentiated recombinant GABAA receptors expressed in HEK-293 cells and in Xenopus laevis oocytes (Halliwell et al., 1999). Together these studies lead to the conclusion that fenamate NSAIDs should now also be considered a robust class of GABAA receptor modulators.

Also demonstrated for the first time here is the direct activation of neuronal GABAA receptors by mefenamic acid. Other allosteric potentiators, including the neuroactive steroids and the depressant barbiturates share this property, with MFA at least equipotent to neurosteroids and significantly more potent than the barbiturates. The mechanism(s) of the direct gating of GABAA receptor chloride channels by MFA requires further investigation using ultra-fast perfusion techniques but may be distinct from that reported for neurosteroids (see, Hosie et al., 2006). Mefenamic acid induced a leftward shift in the GABA dose-response curve consistent with an increase in receptor affinity for the agonist. This is an action observed with other positive allosteric GABAA receptor modulators, including the benzodiazepine agonist, diazepam, the neuroactive steroid, allopregnanolone, and the intravenous anesthetics, pentobarbitone and propofol (e.g. Johnston, 2005). To our knowledge, a unique property of MFA was that it was significantly (F = 10.35; p≤ 0.001) more effective potentiating GABA currents at hyperpolarized holding potentials (especially greater than −60mV). Further experiments are required however to determine the underlying mechanism(s).

The highly effective modulation of GABAA receptors in cultured hippocampal neurons suggests the fenamates may have central actions. Consistent with this hypothesis, mefenamic acid concentrations are 40–80μM in plasma with therapeutic doses (Cryer & Feldman, 1998); fenamates can also cross the blood brain barrier (Houin et al., 1983; Bannwarth et al., 1989) Coyne et al. Page 5 Neurochem Int. Author manuscript; available in PMC 2008 November 1. NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript and in overdose in humans are associated with coma and convulsions (Smolinske et al., 1990). In animal studies, mefenamic acid is anticonvulsant and neuroprotective against seizureinduced forebrain damage in rodents (Ikonomidou-Turski et al., 1988). The present study would suggest that the anticonvulsant effects of fenamates may be related, in part, to their efficacy to potentiate native GABAA receptors in the brain, although a recent study has suggested that activation of M-type K+ channels may contribute to this action (Peretz et al., 2005) Finally, Joo and co-workers (2006) have recently reported that mefenamic acid provided neuroprotection against β-amyloid (Aβ1-42) induced neurodegeneration and attenuated cognitive impairments in this animal model of Alzheimer’s disease. The authors proposed that neuroprotection may have resulted from inhibition of cytochrome c release from mitochondria and reduced caspase-3 activation by mefenamic acid. Clearly it would also be of interest to evaluate the role of GABA receptor modulation in this in vivo model of Alzheimer’s disease. Moreover, considerable evidence has emerged in the last few years indicating that GABA receptor subtypes are involved in distinct neuronal functions and subtype modulators may provide novel pharmacological therapies (Rudolf & Mohler, 2006). Our present data showing that fenamates are highly effective modulators of native GABAA receptors and that mefenamic acid is highly subtype-selective (Halliwell et al., 1999) suggests that further studies of its cognitive and behavioral effects would be of value.

  

Note in the above paper that NSAIDs other than mefenamic acid also modulate GABAA receptors.

Just a couple of months ago a rather complicated paper was published, again showing that NSAIDs modulate GABA_A receptors and showing that this is achieved via the same calcium activated chloride channels (CaCC) referred to by Knut.

NSAIDs modulate GABA-activated currents via Ca²⁺-activated Cl⁻ channels in rat dorsal root ganglion neurons

"Schematic displaying the effects of CaCCs on GABA-activated inward currents and depolarization. GABA activates the GABA_A receptor to open the Cl ⁻ channel and the Cl⁻ efflux induces the depolarization response (inward current) of the membrane of dorsal root ganglion (DRG) neurons. Then, voltage dependent L-type Ca²⁺ channels are activated by the depolarization, and give rise to an increase in intracellular Ca²⁺. CaCCs are activated by an increase in intracellular Ca²⁺ concentration which, in turn, increases the driving force for Cl⁻ efflux. Finally, the synergistic action of the chloride ion efflux through GABA_A receptors and NFA-sensitive CaCCs causes GABA-activated currents or depolarization response in rat DRG neurons."

Note in the complex explanation above the L-type calcium channels, which are already being targeted by Verapamil, in the PolyPill.

Mefenamic Acid and Potassium Channels

We know that Mefenamic acid also affects K_v7.1 (KvLQT1).

A closely related substance called meclofenamic acid is known to act as novel KCNQ2/Q3 channel openers and is seen as having potential for the treatment of neuronal hyper-excitability including epilepsy, migraine, or neuropathic pain.

Meclofenamic Acid and Diclofenac, Novel Templates of KCNQ2/Q3 Potassium Channel Openers, Depress Cortical Neuron Activity and Exhibit Anticonvulsant Properties

The voltage-dependent M-type potassium current (M-current) plays a major role in controlling brain excitability by stabilizing the membrane potential and acting as a brake for neuronal firing. The KCNQ2/Q3 heteromeric channel complex was identified as the molecular correlate of the M-current. Furthermore, the KCNQ2 and KCNQ3 channel  subunits are mutated in families with benign familial neonatal convulsions, a neonatal form of epilepsy. Enhancement of KCNQ2/Q3 potassium currents may provide an important target for antiepileptic drug development. Here, we show that meclofenamic acid (meclofenamate) and diclofenac, two related molecules previously used as anti-inflammatory drugs, act as novel KCNQ2/Q3 channel openers. Extracellular application of meclofenamate (EC50  25 M) and diclofenac (EC50  2.6 M) resulted in the activation of KCNQ2/Q3 K currents, heterologously expressed in Chinese hamster ovary cells. Both openers activated KCNQ2/Q3 channels by causing a hyperpolarizing shift of the voltage activation curve (23 and 15 mV, respectively) and by markedly slowing the deactivation kinetics. The effects of the drugs were stronger on KCNQ2 than on KCNQ3 channel  subunits. In contrast, they did not enhance KCNQ1 K currents. Both openers increased KCNQ2/Q3 current amplitude at physiologically relevant potentials and led to hyperpolarization of the resting membrane potential. In cultured cortical neurons, meclofenamate and diclofenac enhanced the M-current and reduced evoked and spontaneous action potentials, whereas in vivo diclofenac exhibited an anticonvulsant activity (ED50  43 mg/kg). These compounds potentially constitute novel drug templates for the treatment of neuronal hyperexcitability including epilepsy, migraine, or neuropathic pain. Volt

BK channel

KCNMA1encodes the ion channel K_Ca1.1, otherwise known as BK (big potassium). BK channels are implicated not only by Knut’s statistics, but numerous studies ranging from schizophrenia to Fragile X. 

Usually it is a case of too little BK channel activity.

The BK channel is implicated in some epilepsy.

  

Pharmacology

BK channels are pharmacological targets for the treatment of several medical disorders including stroke and overactive bladder. Although pharmaceutical companies have attempted to develop synthetic molecules targeting BK channels, their efforts have proved largely ineffective. For instance, BMS-204352, a molecule developed by Bristol-Myers Squibb, failed to improve clinical outcome in stroke patients compared to placebo. However, BKCa channels are reduced in patients suffering from the Fragile X syndrome and the agonist, BMS-204352, corrects some of the deficits observed in Fmr1 knockout mice, a model of Fragile X syndrome.

BK channels have also been found to be activated by exogenous pollutants and endogenous gasotransmitters carbon monoxide and hydrogen sulphide.

BK channels can be readily inhibited by a range of compounds including tetraethylammonium (TEA), paxilline and iberiotoxin.

BK channel dysfunction and neurological disorders

Achieving a better understanding of BK channel function is important not only for furthering our knowledge of the involvement of these channels in physiological processes, but also for pathophysiological conditions, as has been demonstrated by recent discoveries implicating these channels in neurological disorders. One such disorder is schizophrenia where BK channels are hypothesized to play a role in the etiology of the disease due to the effects of commonly used antipsychotic drugs on enhancing K⁺ conductance [101]. Furthermore, this same study found that the mRNA expression levels of the BK channel were significantly lower in the prefrontal cortex of the schizophrenic group than in the control group [101]. Similarly, autism and mental retardation have been linked to haploinsufficiency of the Slo1 gene and decreased BK channel expression [102].

Two mutations in BK channel genes have been associated with epilepsy. One mutation has been identified on the accessory β3 subunit, which results in an early truncation of the protein and has been significantly correlated in patients with idiopathic generalized epilepsy [103]. The other mutation is located on the Slo1gene, and was identified through genetic screening of a family with generalized epilepsy and paroxysmal dyskinesia [104]. The biophysical properties of this Slo1 mutation indicates enhanced sensitivity to Ca²⁺ and an increased average time that the channel remains open [104–107]. This increased Ca²⁺ sensitivity is dependent on the specific type of β subunit associating with the BK channel [106, 107]. In association with the β3 subunit, the mutation does not alter the Ca²⁺-dependent properties of the channel, but with the β4 subunit the mutation increases the Ca²⁺ sensitivity [105–107]. This is significant considering the relatively high abundance of the β4 subunit compared to the weak distribution of the β3 subunit in the brain [12, 13,15, 106, 107]. It has been proposed that a gain of BK channel function may result in increases in the firing frequency due to rapid repolarization of APs, which allows a quick recovery of Na⁺ channels from inactivation, thereby facilitating the firing of subsequent APs [104]. Supporting this hypothesis, mice null for the β4 subunit showed enhanced Ca²⁺ sensitivity of BK channels, resulting in temporal lobe epilepsy, which was likely due to a shortened duration and increased frequency of APs [108]. An interesting relevance to the mechanisms of BK channel activation as discussed above, the Slo1 mutation associated with epilepsy only alters Ca²⁺ dependent activation originated from the Ca²⁺ binding site in RCK1, but not from the Ca²⁺bowl, by altering the coupling mechanism between Ca²⁺ binding and gate opening [100]. Since Ca²⁺dependent activation originated from the Ca²⁺ binding site in RCK1 is enhanced by membrane depolarization, at the peak of an action potential the binding of Ca²⁺ to the site in RCK1 contributes much more than binding to the Ca²⁺ bowl to activating the channel [84, 109].

Although these associations between specific mutations in BK channel subunits and various neurological disorders have been demonstrated by numerous studies, it is also important to point out certain caveats with these studies, such as genetic linkage between BK channels and different diseases do not necessary show causation as these studies were performed based on correlation between changes in the protein/genetic marker and overall phenotype. Furthermore, studies performed using a mouse model also can fail to indicate what may happen in higher-order species, and this is especially true for BK channels, where certain β subunits are only primate specific [110].

  

Possible role of potassium channel, big K in etiology of schizophrenia.

Schizophrenia (SZ), a common severe mental disorder, affecting about 1% of the world population. However, the etiology of SZ is still largely unknown. It is believed that molecules that are in an association with the etiology and pathology of SZ are neurotransmitters including dopamine, 5-HT and gamma-aminobutyric acid (GABA). But several lines of evidences indicate that potassium large conductance calcium-activated channel, known as BK channel, is likely to be included. BK channel belongs to a group of ion channels that plays an important role in regulating neuronal excitability and transmitter releasing. Its involvement in SZ emerges as a great interest. For example, commonly used neuroleptics, in clinical therapeutic concentrations, alter calcium-activated potassium conductance in central neurons. Diazoxide, a potassium channel opener/activator, showed a significant superiority over haloperidol alone in the treatment of positive and general psychopathology symptoms in SZ. Additionally, estrogen, which regulates the activity of BK channel, modulates dopaminergic D2 receptor and has an antipsychotic-like effect. Therefore, we hypothesize that BK channel may play a role in SZ and those agents, which can target either BK channel functions or its expression may contribute to the therapeutic actions of SZ treatment.

Conclusion

It appears that Ponstan and related substances have some interesting effects that are only now emerging in the research.

People with autism, and indeed schizophrenia, may potentially benefit from Ponstan and for a variety of different reasons.

I think it will take many decades for any conclusive research to be published on this subject, because this is an off-patent generic drug.

As with most NSAIDS, it is simple to trial Ponstan.

Thanks to Knut for the idea, Professor Ritvo for his endorsement of the idea and our reader from South Africa for sharing his positive experience with Ponstan. 

Cardiazol, a failed Schizophrenia treatment from the 1930s, repurposed at low doses as a Cognitive Enhancer in Down Syndrome and likely some Autism

Italy has many attractions, one being Lake Como (Villa Clooney). 

It is also the only western country still using Cardiazol, where it is used in a cough medicine

Varanasi and the Ganges, not a place you could forget, particularly the smell.

India is the only other country using Cardiazol

Today’s post draws on clever things going on in Down Syndrome research to improve cognitive function, but puts them in the perspective of the faulty GABA switch. 

In the United States it is estimated that 250,000 families are affected by Down Syndrome.  It is caused by a third copy of chromosome 21, resulting in up-regulation of around 300 genes.  A key feature is low IQ, this is partly caused by a physically smaller cerebellum and it appears partly by the GABA switch.  Research has shown that the cerebellum growth could be normalized, but this post is all about the GABA switch. 

In an earlier very science heavy post we saw how a faulty GABA switch would degrade cognitive function in many people with autism, schizophrenia or Down Syndrome. Basmisanil is a drug in Roche’s development pipeline.

The GABA Switch, Altered GABAa Receptor subunit expression in Autism and Basmisanil

   

More evidence to show the GABA switch affects schizophrenia was provided by our reader Natasa.

Gain-of-function missense variant in SLC12A2, encoding thebumetanide-sensitive NKCC1 cotransporter, identified in human schizophrenia

Perturbations of γ-aminobutyric acid (GABA) neurotransmission in the human prefrontal cortex have been implicated in the pathogenesis of schizophrenia (SCZ), but the mechanisms are unclear. NKCC1 (SLC12A2) is a Cl^--importing cation-Cl^- cotransporter that contributes to the maintenance of depolarizing GABA activity in immature neurons, and variation in SLC12A2 has been shown to increase the risk for schizophrenia via alterations of NKCC1 mRNA expression. However, no disease-causing mutations or functional variants in NKCC1 have been identified in human patients with SCZ. Here, by sequencing three large French-Canadian (FC) patient cohorts of SCZ, autism spectrum disorders (ASD), and intellectual disability (ID), we identified a novel heterozygous NKCC1 missense variant (p.Y199C) in SCZ. This variant is located in an evolutionarily conserved residue in the critical N-terminal regulatory domain and exhibits high predicted pathogenicity. No NKCC1 variants were detected in ASD or ID, and no KCC3 variants were identified in any of the three neurodevelopmental disorder cohorts. Functional experiments show Y199C is a gain-of-function variant, increasing Cl^--dependent and bumetanide-sensitive NKCC1 activity even in conditions in which the transporter is normally functionally silent (hypotonicity). These data are the first to describe a functional missense variant in SLC12A2 in human SCZ, and suggest that genetically encoded dysregulation of NKCC1 may be a risk factor for, or contribute to the pathogenesis of, human SCZ.

This study showed that some with schizophrenia will likely benefit from Bumetanide, but that the underlying reason for excessive NKCC1 activity in schizophrenia is not the same as in ASD.  Different cause but the same end result and the same likely therapy, repurposing an old existing drug.

α3 and α5 sub-units of GABA_A

The science is rather patchy, but it seems that the α3 sub-unit of GABA_A receptors is under-expressed in some autism and there is a fair chance that the α5 sub-unit is correspondingly over-expressed.

We know that over-expression of α5 is associated with cognitive impairment.

Down regulating α5 is currently a hot topic in Down Syndrome and at least two drugs are in development.

Reading the Down Syndrome research suggests that those involved have not really understood what is going on.  They do seek to modify GABA signaling, but have not realized that likely problem is the miss-expression of GABA_A subunits in the first place, exactly as in autism.  As in autism, this faulty “GABA switch” has more than one dimension.  An incremental benefit can be expected from correcting each one.


Further support for the use of low dose Clonazepam in some Autism

In previous posts we saw how Professor Catterall's idea to use low dose clonazepam to treat some autism does translate from mice to humans.  This was based on up-regulating the α3 sub-unit of GABA_A receptors.

There is some new research on this subject and Japanese research is very often of the highest quality.

In the paper below, highlighted by our reader Tyler, they use low dose clonazepam to reduce autistic behavior in a rare condition called Jacobsen syndrome.  While Professor Catterall and several readers of this blog are using low dose clonazepam to upregulate the α3 sub unit of GABA_A receptors, the Japanese attribute the benefit to the γ2 subunit.

Whichever way you look at it, another reason to support trial of low dose clonazepam in autism.  When I say low, I mean a dose 100 to 1,000 times lower than the standard doses.

PX-RICS-deficient mice mimic autism spectrum disorder in Jacobsen syndrome through impaired GABAA receptor trafficking 

Jacobsen syndrome (JBS) is a rare congenital disorder caused by a terminal deletion of the long arm of chromosome 11. A subset of patients exhibit social behavioural problems that meet the diagnostic criteria for autism spectrum disorder (ASD); however, the underlying molecular pathogenesis remains poorly understood.

ASD-like behavioural abnormalities in PX-RICS-deficient mice are ameliorated by enhancing inhibitory synaptic transmission with a GABA_AR agonist (Clonazepam)

   

A curative effect of clonazepam on autistic-like behaviour

 These results demonstrate that ASD-like behaviour in PX-RICS^−/− mice is caused by impaired postsynaptic GABA signalling and that GABA_AR agonists have the potential to treat ASD-like behaviour in JBS patients and possibly non-syndromic ASD individuals.

“Correcting GABA” in Down Syndrome

I expect there may be four different methods, all relating to GABA_A, to improve cognition in Down Syndrome just as there appear to be in autism:-

·        Reduce intracellular Cl- by blocking NKCC1 with bumetanide

 ·        Down regulate α5 sub-units of GABA_A

 ·        Damp down GABAA receptors with an antagonist

 ·        Upregulate α3 sub-units of GABA_A

Two of the above are being pursued in Down Syndrome research, but two do not seem to be.

Enhancing Cognitive Function in Down Syndrome

These are the sort of headlines that appeal to me:-

IQ-Boosting Drugs Aim to Help Down Syndrome Kids Learn

Cognitive-enhancing drugs may have a significant impact, doctors say. An IQ boost of just 10 to 15 points could greatly increase the chance that someone with the syndrome would be able to live independently as an adult, said Brian Skotko, co-director of the Down syndrome program at Massachusetts General Hospital in Boston, who has a sister with the condition.

In 2004, Stanford University neurobiologist Craig Garner and a student of his at the time, Fabian Fernandez, realized scientists might be able to counteract the Down Syndrome with drugs…

Researchers did a test in mice using an old GABA-blocking drug called PTZ. After 17 days, the treatment normalized the rodents’ performance on mazes and certain object recognition and memory tasks for as long as two months, according to results published in 2007 in Nature Neuroscience….

“It was bloody amazing,” Garner said by telephone. “It was shocking how well it worked.”

  

Inhibiting Inhibition to Treat Down Syndrome Symptoms

In their work, Hernandez, who is at Roche AG, and colleagues both at Roche and in academia chronically treated mice that have an animal version of Down syndrome with RO4938581, a drug that targets GABA receptors containing an alpha5 subunit. GABA is the major inhibitory transmitter in the brain, and in Down syndrome, there appears to be too much inhibitory signaling in the hippocampus – where, it so happens, GABA receptors with the alpha5 subunit are concentrated.

Treatment with RO4938581 improved the animals' memory abilities in a maze, decreased hyperactivity and reversed their long-term potentiation deficit. In the hippocampus, which is an important brain structure for memory and cognition, it also increased the birth rate of neurons back to the levels seen in normal animals, and led to a decrease in the number of inhibitory connections between cells.

  

In short there are two methods being developed, both potentially applicable to some autism:-

METHOD 1.   Dampen GABA_A receptors with an antagonist

METHOD 2.   Dampen GABA with an inverse agonist of α5 sub-unit  

Initially it was thought method 1 could not be used because of the risk of seizure/epilepsy.

“these drugs (GABA_A antagonists) are convulsant at high doses, precluding their use as cognition enhancers in humans, particularly considering that DS patients are more prone to convulsions”

From:-

Specific targeting of the GABA-A receptor α5 subtype by a selective inverse agonist restores cognitive deficits in Down syndrome mice

  

However this seems to have been overly conservative.

In the 2007 Stanford study they make a big point of their dosing being far lower than that used to induce seizures.

While you may need for a decade to get hold of Basmisanil (method 2), Cardiazol/PZT (method 1) is available in some pharmacies today.  The only complication is that it is in a cough medicine that also contains Dihydrocodeine.

In some countries Dihydrocodeine is used in OTC painkillers along with paracetamol or ibuprofen, while in other countries it is a banned substance.

In Italy and India Cardiazol, with Dihydrocodeine, is given to toddlers as a cough medicine.

  

METHOD 1.   Dampen GABA_A receptors with an antagonist

  

As seems to be the case quite often, you can sometimes repurpose an old drug rather than spend decades developing a new one.  This is the case with Cardiazol/ Pentylenetetrazol that was used in the Stanford trial.

Confusing Medical Jargon, (again)

Cardiazol, the name an elderly psychiatrist would recognize, is also called:-

·        Pentylenetetrazol
·        Pentylenetetrazole
·        Metrazol
·        Pentetrazol
·        Pentamethylenetetrazol
·        PTZ
·        BTD-001 

·        DS-102

Other than to confuse us, why do they need so many names for the same drug?

Cardiazol/ Pentylenetetrazol is a drug that was widely used in the 1930s in Mental Hospitals to trigger seizures that were supposed to treat people with Schizophrenia.  At much lower doses, it found a new purpose decades ago as an ingredient in cough medicine.

Electroconvulsive therapy later took the place of Cardiazol, as psychiatrists sought to treat people by terrifying them.  It was later concluded that the only benefit in giving people Cardiazol was the fear associated with it. Electroconvulsive therapy is still used today in autism.

  

For a background into Cardiazol as a schizophrenia therapy, the following is not very pleasant reading:-

  

‘A violent thunderstorm’: Cardiazol treatment in British mental hospitals

  

The 2007 Stanford trial of Cardiazol (there called PTZ) also trialed another GABA_A antagonist called picrotoxin (PTX).  Picrotoxin is, not surprisingly, a toxin, it is therefore a research drug but it has been given to horses to make them run faster.

Pharmacotherapy for Cognitive Impairment in a Mouse Model of Down Syndrome

  

Recent neuroanatomical and electrophysiological findings from a

mouse model of Down syndrome (DS), Ts65Dn, suggest that there is

excessive inhibition in the dentate gyrus, a brain region important for

learning and memory. This circuit abnormality is predicted to compromise normal mechanisms of synaptic plasticity, and perhaps mnemonic processing. Here, we show that chronic systemic administration of noncompetitive GABAA antagonists, at non – epileptic doses, leads to a persistent, post drug, recovery of cognition in Ts65Dn mice, as well as recovery of deficits in long – term potentiation (LTP). These data suggest that excessive GABAergic inhibition of specific brain circuits is a potential cause of mental retardation in DS, and that GABAA antagonists may be useful therapeutic tools to facilitate functional changes that can ameliorate cognitive impairment in children and young adults with the disorder.

One important things is that this cognitive enhancing effect persisted for a couple of months.

As you will see in the human clinical trial at the end of this post, they are comparing single doses with daily doses to understand the pharmokinetics.

The lead author, Craig Garner went on to start his own company because nobody seemed interested in his findings.

http://balance-therapeutics.com/

“Balance is now testing a GABA-blocking drug, BTD-001, on 90 adolescents and adults with Down syndrome in Australia, with results expected by early next year, said Lien, chief executive officer of the company.”

GABA_A agonists and antagonists

The jargon does get confusing, if you want to stimulate GABA_A receptors, you would use an agonist like GABA itself, or something that mimics it.

If you want to damp down the effect of GABA_A receptors you would need an antagonist.

So if GABA_A receptors are “malfunctioning”, you could either fix the malfunction or turn them down to reduce their effect.

If you cannot entirely repair the malfunction you could always do both.  The overall effect might be better, or might not be, and it might well vary from person to person depending on the degree and nature of malfunction.

We saw in a previous post the idea of using drugs like bumetanide, diamox, and potassium bromide to restore E/I balance and then give GABA a little boost with a GABA agonist like Picamillon.  This is very easy to test.  In our case that little boost, did not help.

In those people who do not respond well, we can take the idea developed by Stanford for Down Syndrome and do the opposite, use a tiny amount of an antagonist, to see if that fine tuning has any beneficial effect.  We now see this is both simple and safe.

METHOD 2.   Inverse agonists of α5 sub-unit GABA_A

I do like method 2, but would prefer not to wait another decade.

Method 2 sets out to improve cognitive function by dampening the activity of α5 sub-unit GABA_A.

The Downs Syndrome researchers at Roche are developing Basmisanil/RG-1662 for this purpose.  It will be a long while till it appears on the shelf of your local pharmacy.

I did look to see if there any clever ways to down regulate the α5 sub-unit of GABA_A , other than those drugs being developed for Down Syndrome. 

Inverse agonists of of α5 sub-unit GABA_A

• α₅IA
• Basmisanil (RG-1662, RO5186582): derivative of Ro4938581, negative allosteric modulator at GABA_A α₅, in human trials for treating cognitive deficit in Down syndrome.^[3]
• L-655,708
• MRK-016
• PWZ-029: moderate inverse agonist^[4]
• Pyridazines^[5]
• Ro4938581^[6]
• TB-21007^[7][8]

The only option today would be the Pyridazines, which include cefozopran (a 4^th generation antibiotic), cadralazine (reduces blood pressure), minaprine (withdrawn antidepressant), pipofezine (a Russian a tricyclic antidepressant), hydralazine (reduces blood pressure, but has problems), and cilazapril (ACE inhibitor).

Pipofezine looks interesting.

Now we can compare Pipofezine with Mirtazapine.   They are both this tricyclic antidepressants, so both closely related to H1 antihistamine drugs.  We saw in earlier posts that Mirtazapine helps some people with autism in quite unexpected ways.

  

To be classed as a Pyridazines there has to be the benzene ring with two adjacent nitrogen atoms

So mirtazapine is not quite a Pyridazine, so may not directly affect the α5 sub-unit; but it does have potent effects elsewhere on the same receptor.  It is will increase the concentration of neuroactive steroids that act as positive allosteric modulators via the steroid binding site on GABA_A receptors.

  

We saw this in earlier posts that changes in progesterone levels affect not only the function of GABA_A but even the subunit composition and hence indirectly possibly α5 sub-unit expression.

I previously suggested both progesterone and pregnenalone as potential autism therapies.  Pregnenalone has since been trialed at Stanford.

The problem with these substances is that they are also female hormones and giving them in high doses to young boys is not a good idea.  Stanford used adults in their trial.

However, affecting the metabolites of progesterone rather than increasing the amount of progesterone itself may give the good, without the bad.  Also, perhaps there is a reason, oxidative stress perhaps, why progesterone metabolism might be disturbed in autism?

Anyway, it is yet another plausible reason why mirtazapine helps some people with autism.

Influence of mirtazapine on plasma concentrations of neuroactive steroids in major depression and on 3-hydroxysteroid dehydrogenase activity

Certain 3-reduced metabolites of progesterone such as 3,5-tetrahydroprogesterone (3,5-THP, 5-pregnan-3-ol-20-one, allopregnanolone) and 3,5-tetrahydroprogesterone (3,5-THP, 5-pregnan-3-ol-20-one, pregnanolone) are potent positive allosteric modulators of the -aminobutyric acid_A (GABA_A) receptor complex.^1, 2, 3

 Mirtazapine affects neuroactive steroid composition similarly as do SSRIs. The inhibition of the oxidative pathway catalyzed by the microsomal 3-HSD is compatible with an enhanced formation of 3-reduced neuroactive steroids. However, the changes in neuroactive steroid concentrations more likely reflect direct pharmacological effects of this antidepressant rather than clinical improvement in general.

So there may indeed be an effect on α5 sub-unit GABA_A, but there is also an effect on another α5 subunit, this time the nicotinic acetylcholine receptors (nAChR).  Those I looked at in earlier posts.  This is getting rather off-topic.

The gene that encode the α5 sub-unit of nAChR is called CHRNA5.  It is associated with nicotine dependence (and hence lung cancer), but is also linked to anxiety.  GABA sub-units expression also plays a key role in anxiety.  So a reason Mirtazapine should help reduce anxiety.

  

Progesterone modulation ofα5 nAChR subunits influences anxiety-related behavior during estrus cycle 

 It has already been shown that GABA_A receptor subunit expression and composition is modulated by progesterone both in vitro and in vivo(Biggio et al. 2001; Griffiths & Lovick 2005; Lovick 2006; Pierson et al. 2005; Weiland & Orchinik 1995) but this is the first report showing an effect of physiological concentrations of progesterone on nAChR subunit expression levels.

Pharmokinetics of Cardiazol

Since mouse experiments indicated an effect that continues after stopping using the drug, the clinical trials are particularly looking at the so called pharmokinetics.  What is best a small daily dose or occasional larger doses?

You would hope they will be keeping a watchful eye on seizures.

I do not know what doses was used in those mental hospitals in the 1930s, but it must be well documented somewhere.

Safety and Efficacy Study of Orally Administered DS102 in Healthy Subjects

Experimental doses in adults vary widely from a “one off” 100mg to a daily dose of 2000mg. Look how they treat the 7 cohorts in the trial.

The cough medicine has 100mg of Cardiazol per 1ml

The usual dose is one drop per year of age, so a 12 year old would have a 0.6ml  dose containing 60mg of Cardiazol.  That is dosage is give 2 to 4 times a day, so up to 240mg a day

This dose is well up there with the dosage used in the above clinical trial, which starts at a one off dose of just 100mg or daily doses of 500mg in adults.

The above trial has been completed but the results have not been published.

If the trial is positive at the lower dose range, the cough medicine is a very cheap alternative.

Conclusion

I wish a safe inverse agonist of the α5 sub-unit of GABA_A existed for use today.

I do not know anyone with Down Syndrome and this blog does not have many readers from Italy.  The standard pediatric dose of Cardiazol Paracodina  cough medicine might be well worth a try for both those with Down Syndrome and some autism with cognitive dysfunction. 

We actual have quite a few readers from India and that is the only other country using this drug.  In India the producer is Nicholas Piramal and the brand name is Cardiazol Dicodid, it cost 30 US cents for 10ml.  So for less than $1, or 70 rupees, you might have a few months of cognitive enhancement, that is less than some people pay for 1 minute of ABA therapy.

If a few drops of this children’s cough medicine improves cognition please lets us all know.