Thursday, November 13, 2008

Pseudoephedrine

No, this post will not be about the federal law which keeps pseudoephedrine products behind the pharmacy counter. For the record, I honestly couldn't care less about the methamphetamine problem in this or any other country. If someone wants to take the initiative to buy 100 boxes of sudafed and cook up some meth in their basement, it doesn't bother me in the least bit. After all, I'm not the one that's developing a life threatening addiction for the sake of getting high. I'm not the one throwing my life away. Moreover, alcohol is a far bigger problem in this country than methamphetamine ever could be, but no one is trying to make alcohol illegal. If you want to fight a war on drugs, then I propose throwing alcohol in there for the sake of consistency.

Anyway...

When a customer comes to the counter with nasal congestion and wants some advice about which product to take, we always ask one question: "Do you have high blood pressure or take medication to treat high blood pressure?" If the patient answers yes, we automatically rule out the only OTC option that's effective for nasal congestion. In fact, it's one of the only OTC drugs that actually is effective at all.

With every new study that comes out, dextromethorphan looks less and less effective at suppressing cough. Guaifenesin has never really been proven to break up chest congestion. Ask allergy sufferers how well loratidine (Claritin) works for them, and you'll meet some pretty disappointed people. Pseudoephedrine really does work to relieve nasal congestion though, which is more than we can say about its replacement, phenylephrine.

If it's effective, then why are we so quick to rule it out for people taking antihypertensives? The answer we're taught to give is that pseudoephedrine can raise your blood pressure, which would be bad for a person that already has high blood pressure. However, I contend that a short, as needed course of pseudoephedrine probably isn't any more harmful than a stressful day at work. Moreover, someone who's blood pressure is well controlled by antihypertensive medication is at as much risk as someone who doesn't have high blood pressure and doesn't take any medication.

If you really look at the data, pseudoephedrine's effect on blood pressure isn't all that alarming. This patient counseling point is pounded into us from the very beginning of pharmacy school as if taking pseudoephedrine could send someone into a hypertensive crisis. In reality, it raises blood pressure by a few points on average, and its effect certainly isn't powerful enough to offset someone taking one or several antihypertensive medications.

If you really want to get serious about all these OTC interactions, we can include some we usually don't talk about. For example, someone taking beta blockers such as metoprolol or carvedilol for high blood pressure or chronic heart failure probably shouldn't be taking antihistamines either. Both metoprolol and carvedilol are metabolized by cytochrome P450 2D6, and most over the counter first generation antihistamines (i.e. diphenhydramine) inhibit 2D6, which would raise the levels of those drugs in their systems and put them at risk for a bradycardic episode. That never seems to stop us from recommending these products to people taking metoprolol or carvedilol, and rightfully so because the risk just isn't that great.

It's the same with pseudoephedrine. For the vast majority of cold sufferers the risk of a short, as needed course of pseudoephedrine causing an adverse event is very small. Therefore, when these situations come up, I usually ask patients if their high blood pressure is being well-controlled by their medication. If they say yes, I ask them if they check their blood pressure regularly and ask what the results tend to be. If they say that every time they go to their doctor's office, their blood pressure comes out 120/80 (or close to it), then I tell them that while pseudoephedrine can possibly raise blood pressure a small amount, using it for a few days on an as needed basis is generally safe. However, if the nasal congestion lasts more than 3 days, and/or you're not getting any relief from the pseudoephedrine, contact your doctor.

Of course, if the person has high, uncontrolled blood pressure, CHF, or poorly controlled diabetes, I wouldn't recommend pseudoephedrine products. However, in the other cases I mentioned, I feel like pharmacists are too quick to rule out one of the few effective OTC cold medications.

6 comments:

Eric, AKA The Pragmatic Caregiver said...

Take a gander at the American Academy of Chest Physicians' guidelines on treating chronic cough - I was really astonished. They recommend chlor-trimetron at bedtime, or, get this: naproxen. I was really blown away, and pulled the original paper that tested this. Now, maybe I'm really suggestible, but I find that an Rx-sized dose of naproxen not only relieves the miserable achy feeling, but really does take the cough down to a dull roar, better than codeine cough syrup. Who knew?

A question: let's say that the naproxen label is 220mg bid for adults, and you're aware of high-quality RCT evidence that something closer to the Anaprox DS dose is required. What do you tell patients regarding the dose, given that you're talking about more than the label dose, but still within the realm of commonly-used doses?

E

Anonymous said...

im a pharmacy student in australia, we do recommend pseudoephedrine OTC for nasal congestion to people with controlled hypertension for short term use.

The Ole' Apothecary said...

Eric, your find would work almost every time in Harvard Square, Cambridge, MA, but I don't know about getting it across in Market Square, Houlton, ME.

I usually found a simple recommendation difficult enough to sell, but getting someone to ignore the product labeling to get to a sophisticated truth, is, like, oy, veh! It's worth a try, I guess.

Anonymous said...

I heard that there's a nasal pseudoephedrine out...was I dreaming? I also saw there's a product that's called Mucinex nasal that contains what's in generic Afrin (oxymetazolone sp?). Can you believe it?

As for cough and cold recommendations. Pharmacist's Letter lists both the naproxen, and also discusses the pseudoephedrine. It's a brief synopsis, but have found its references and tables supply a wealth of information, especially with regard to OTC drugs to use in pregnancy.

My personal preference for nasal congestion, two sniffs of generic Afrin (the bottle has to be at least 3 yrs outdated as I'm sensitive to its effects), and a sniff of some new Flonase, plus a bite of, maybe half an extra-strength Tylenol, then to bed with the covers pulled up over my head. Sorry, almost facetious, but this combination usually takes care of the problem, unless I have to be at work at 7:30 AM, then I might as well get up and drink hot orange tea.

Shalom said...

Contrary data point: I can't take PSE. It gives me insomnia, palpitations, and lethal irritability. Worst of all, it doesn't even clear my nose.

(I'm also one of those 19% that get drowsy on cetirizine. The one time I tried Zyrtec-D, I had simultaneous sedation and insomnia. Not fun.)

So I have to use phenylephrine. It does a so-so job on my nose, and gives me none of the other effects listed above. I was getting it by prescription before Sudafed PE came out (it was called "Ah-Chew D", I kid you not). I really miss PPA, which worked much better than either of the two currently available decongestants... of course now that I'm on atenolol it probably wouldn't be a good idea.

The Ole' Apothecary said...

Mike, I received an interesting comment on my old PSE post. The poster said I was wrong when I said that PSE is not directly abusable. It is true that people will take up to one gram of the stuff so they can achieve what they call "skittling," whatever that is? I wouldn't know about this because I have been out of retail practice for 15 years.

If PSE is inherently abusable in addition to being a meth precursor, it really ought to go Rx-only. Such a move would not only protect the public even more, it would eliminate the PSE bean counting we pharmacists have to do, and increase both our Rx volume and our clinical involvement.