In my previous posts on histamine, you
would have read that I found that Claritin appeared to reduce autistic
behaviours. Once I had got to the bottom
of what was going on, I found out that histamine has a long record of
stimulating challenging behaviour in all children. It also became clear that typical
anti-histamines (H1 antagonists) are all slightly different and one may be
effective in one person and ineffective in another. Each one tends to have additional secondary effects.
The Brazilian paper does rather contradict some of what Dr Theoharides says about stabilizing mast cells. You can choose who you think has got it right. The good thing is that both Dr Inês Cristina Camelo-Nunes and Dr Theoharides seem very serious, objective people, which cannot be said about all the people offering their advice on the internet.
In fact, I found an interesting paper on the anti-inflammatory effects of the new version of Claritin, called Aerius/Clarinex (Desloratadine).
It really seems to be the case of trying several antihistamines and selecting the one that works best for you.
The role of histamine H4 receptor in immune and inflammatory disorders
Here is a graphic from that paper:-
I wonder if that H4 is a ticking bomb in
autism as well ?
Those more peaceful people among you will be less aware of what C4 is, and hence the sticks of H4 dynamite.
It now appears that the secondary effect of
certain H1 antagonists may actually be more important than the primary intended
effect of reducing itchy eyes and runny noses.
There are three generations of H1 drugs. The fastest working and most potent is still
the first generation, the second generation are non-drowsy derivatives of the
first generation. The third generation
are the active metabolite of the second generation. As you will see in today’s central paper, the
third generation probably does not warrant the tittle. For many users they may be just expensive
versions of the second generation drug.
The excellent paper New anti histamines: a critical view is from Brazil, but it has an English
version. It is highly readable. It tells of the specific secondary effects of
certain second generation H1 antagonists.
(She omits to mention the secondary
effects of the first generation. Some people say Ketotifen is 1st
generation and other people say 2nd generation, anyway it appears
not to be sold in Brazil). I suggest you
read the paper, if you have a child with an ASD. The key section is this:
Antiallergic/anti-inflammatory effects
Originally, studies of the relative potencies of H1 antihistamines
were based on the capacity of different compounds to competitively inhibit the
H1 receptor binding of histamine, i.e. on their blocking effect on the
receptor.8 Nevertheless, it has already been known for some time
that, in addition to acting on H1 receptors, many H1 antihistamines, at
appropriate doses, are capable of inhibiting not only the release of histamine
by mast cells,9,10 but also mast cell activation itself.11
Some of them can even regulate the expression and/or release of cytokines,
chemokines, adhesion molecules and inflammatory mediators.5,8
Therefore, the antiallergic properties of H1 antihistamines are
generally a reflection of their capacity to affect mast cell and basophil
activity, inhibiting the release of preformed mediators such as histamine,
tryptase, leukotrienes and others.8 Several second-generation H1
antihistamines have demonstrated antiallergic properties, irrespective of their
interaction with the H1 receptor.5,8
Chronic allergic inflammation resulting from the late-phase
reaction, exhibits components that are similar to other forms of inflammation,
including chemotaxis of inflammatory cells followed by activation and
proliferation, with subsequent production and release of many chemical
mediators. Among cells involved in allergic inflammation are:
antigen-presenting cells (for example, macrophages), mast cells, basophils, T
lymphocytes, epithelial/endothelial cells and eosinophils - major effectors of
chronic inflammation. Cytokines, chemokines, inflammatory mediators and
adhesion molecules also contribute to this process which ultimately leads to
dysfunction of the affected organ.8
Many second-generation H1 antihistamines (particularly cetirizine)
are capable of inhibiting the influx of eosinophils to the site of allergen
challenge in sensitized individuals.5,8 Studies have demonstrated
that some of them can also alter adhesion molecules expression on epithelium
and eosinophils, and reduce in vitro survival of eosinophils. Finally,
some second-generation H1 antihistamines are capable, in vitro and in
vivo, of altering the production of inflammatory cytokines (for example,
TNF-a, IL-1b and IL-6) and the Th1/Th2 balance regulation cytokines (for example,
IL-4 and IL-13).5,8
Therefore, it is well established that, in addition to their
effects on H1 receptors, many second-generation H1 antihistamines also manifest
antiallergic and anti-inflammatory properties which differ depending upon their
molecules and the experiments used for their evaluation.5
From my own experience, I have already
replaced Claritine (Loratadine) with Cetirizine to see if it will remain active
for longer. Rather than working for 24
hours, Claritine is working for about 5 hours.
I thought Cetirizine might remain active
for longer, but the main difference seems to be in how it works, rather than
for how long it works. With Cetirizine
autistic behaviour has pretty much returned to where it was at the start of
summer, before the allergy season. With Claritine things improved greatly, but not all the way back to "normal".
Reading the paper and one of its
references -
makes me think that the expensive new version of Cetirizine, called Levocetirizine,
might be even better. It happens to be
available locally, but it is seven times as expensive.The Brazilian paper does rather contradict some of what Dr Theoharides says about stabilizing mast cells. You can choose who you think has got it right. The good thing is that both Dr Inês Cristina Camelo-Nunes and Dr Theoharides seem very serious, objective people, which cannot be said about all the people offering their advice on the internet.
In fact, I found an interesting paper on the anti-inflammatory effects of the new version of Claritin, called Aerius/Clarinex (Desloratadine).
The H4
Histamine Receptor and Inflammation
You may recall that there is a fourth
histamine receptor, naturally called H4.
It was only recently discovered, as you
might guess from the short entry in Wikipedia.
It seems that the H4 receptor plays a substantial role in the
inflammatory response. It is seen as
playing a key role in conditions ranging from arthritis to asthma.
Here is a full text paper for those
interested in the science:-The role of histamine H4 receptor in immune and inflammatory disorders
Those more peaceful people among you will be less aware of what C4 is, and hence the sticks of H4 dynamite.