claritin

Probably. It has extensive first pass metabolism through CYP3A4. Though I haven't seen any info on tolerance on epocrates, wiki, or drugs.com. I guess H1-receptors could eventually be upregulated, but I don't know.

Is it true for the 'regular' claritin, or claritin-d (w/pseudoephedrine), or both?
All I know is it's a bummer since my allergies are out of control now.
And BTW, claritin-d every day for several years has been known to cause hypertension.
Apparently my allergist didn't know this.

Dammit no wonder my eyes itched like crazy today, even after taking the claritin OTC.


I want to go live on the frozen tundra of north canada or something, so I never have to deal with pollen.

ha, actually that was the swine flu. we're all gonna dieee!!!!

Because 10mg is not an effective dose, and eventually the placebo effect wears off.

Sorry to spoil the fun.

reduction of the placebo effect after a longer period of time? Actually I'm not joking all that much here. I don't know the exact data, but I would be surprised if there wasn't a significant placebo effect in the overall efficacy of anti-seasonal allergy meds

Forthegood said:

Because 10mg is not an effective dose, and eventually the placebo effect wears off.

Sorry to spoil the fun.

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...goddamn, you just beat me to the placebo effect hypothesis.

Interesting about the 10mg not being an effective dose.

I'm also tempted to double up my dose.

On the box it says not to take more than one tablet in 24 hours.

Normal dosage is 40mg. But this is not medical advice. Get a Merck manual... loratadine.

isnt that why there are a lot of different kinds of anti-histamines? by the time all of them are used through in a hypothetical person with a supposed allergy, newer meds are most likely created... or the hypothetical person can just go back to claritin again since the tolerance probably wore off

The thing with Claritin (loratadine) is that the regular 40mg pod causes drowsiness (like every other thing on the market), so instead the company lowered the dosage to below therapeutic levels so the trials submitted wouldn't show drowsiness as a symptom... so they could market "Non-drowsy Claritin" and charge a fortune (they do). Worked like a charm. People are sheep.

Forthegood said:

The thing with Claritin (loratadine) is that the regular 40mg pod causes drowsiness (like every other thing on the market), so instead the company lowered the dosage to below therapeutic levels so the trials submitted wouldn't show drowsiness as a symptom... so they could market "Non-drowsy Claritin" and charge a fortune (they do). Worked like a charm. People are sheep.

Click to expand...

Man are you a PharmD...this is exactly correct....I still take old school dallergy

bigpharmD said:

Man are you a PharmD...this is exactly correct....I still take old school dallergy

Click to expand...

Thanks, but really, I know next to nothing. I just read alot.

IIRC, Allegra is the only of the newer, long-lasting antihistamines to reliably not cause drowsiness at effective doses. Zyrtec does cause drowsiness, but I think it's a more idiosyncratic response. I'm sure someone out there has better or more up-to-date information.

Forthegood said:

Thanks, but really, I know next to nothing. I just read alot.

Click to expand...

yeah i know a pharmd who reviewed the literature....you know the effective dose of phenylephriine (sold OTC) is like 3 x the recommended dose...the problem is thats when it increases BP and heart rate...there are some people petitioning the FDA to get it taken off the market

colbgw02 said:

IIRC, Allegra is the only of the newer, long-lasting antihistamines to reliably not cause drowsiness at effective doses. Zyrtec does cause drowsiness, but I think it's a more idiosyncratic response. I'm sure someone out there has better or more up-to-date information.

Click to expand...

prob the most effective drug is hydroxyzine, but causes some drowsiness which you can get used to. Zyrtec is just the "active form" so in my opinion works better than the others,but still might cause some drowsiness. Personally I think all of the newER agents suck and dont work for anyone with moderate to severe allergies.

Oral decongestants are not that effective anyway and have a lot of systemic side effects. So yes, if you have Claritin-D it won't work as well over time and probably shouldn't be a long-term medication. The nasal sprays are far better for nasal congestion. Obviously not for more than three days at a time because of upregulation of adrenergic receptors and a nasty rhinitis medicamentosa. This is why the steroids are a good option for chronic sinusitis until they aren't powerful enough. Speaking of, my dad is probably going to have surgery soon for a polyp in his nose he's had since the 80s. His nose is pretty much non-functional.

I use cetirizine and I can definitely tell if I forget to take it a couple of days I get hives and often a more reactive airway. I have intermittent asthma that is usually only apparent when I have a URI/bronchitis or when I'm around a lot of cats. Since I'm around cats about three days a week at my fiancée's house I'd say it works pretty well for me as it is and I only need a bronchodilator on very rare occasions.

As for antihistamines and drowsiness, the newer agents are less potent anticholinergics and don't pass the blood brain barrier as much. "Supposedly" levocetirizine (the L-enantiomer of cetirizine) has fewer side-effects but it's probably just a marketing scheme.