----- Original Message -----
From: "Skipper Beers" <[log in to unmask]>


> Bad thing about the Claritin was the excessive
> dry mouth it caused.  Not only does it make it hard to talk but causes
> cavities.  As all the allergy medicines seems to do, it also causes
irregular
> heartbeat.  And they think it's safe for the heart but thyroid isn't!
> Claritn came on the market around the time Seldane did but that was
removed
> for killing too many people.  Especially if they took their meds with
> grapefruit juice.  Claritin probably kills, too just not as obvious


Hi Skipper and us group,

Most drugs nowadays are metabolised by the liver's isoenzyme system
called Cytochrome P450 system. This is a group of distinct sub-families
of enzyme systems used by the liver to process different substances as
they come inside the body. Interestingly, some drugs by their chemical
nature become substrates, inducers, or inhibitors of some of these
isoenzyme sub-families. A substrate drug means it is primarily
metabolized by a particular isoenzyme system to yield its therapeutic
form. A good example are the anti-hypertensive drugs called ACEI
(Angiotensin Converting Enzyme Inhibitors). These drugs, while in tablet
form come in its pro-drug or precursor state (e.g., quinapril) when
metabolized by the liver to its active form it becomes quinaprilat.
Inducer drugs enhances the metabolic activity of a particular isoenzyme
system thereby promoting the time-to-peak concentration of a particular
substrate drug with resultant enhanced elimination. Inhibitor drugs as
the name implies retards or completely blunts the metabolism of a
particular substrte drug with resulting accumulation of the drug in the
bloodstream.

As you have noted the dry mouth side-effect of Claritin (Loratadine),
this would tend to be magnified if you are concurrently taking
Cytochrome P450 3A4 (CYP450 3A4) inhibitors like Ketoconazole,
erythromycin, etc. These drugs are documented to increase the plasma
concentration of Claritin. Fortunately, Claritin is also partially
metabolized by another isoenzyme -- CYP450 2D6 thus avoiding too much
accumulation in the event of co-administration with  inhibitors.

Another antihistamine (Astemizole) was taken off from the market due to
drug interactions resulting in heart related adverse events. Likewise,
the popular Intestinal Motility Enhancer Prepulsid (cisapride) was taken
off due to its tendency to produce fatal arrhythmias when combined with
some drugs.

So, being patients we are burdened even more to protect ourselves not
only from the disease being treated by more so from the professionals
who are not aware of these drug-drug interactions

Hope this helps but pardon me for not making it any simpler -- I am
myself confused at times by the terms!

Greg




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