Please explain the difference between pseudoephedrine and phenylephrine, in particular why one works better than the other at different times.
Pseudoephedrine vs. Phenylephrine?
Question posted by GKDdrugs on 13 Jan 2010
Last updated on 21 September 2017
This question has also been asked and answered here: Phenylephrine vs Pseudoephedrine - What's the difference between them?
From a pharmacist at Walgreens:
What's the difference between phenylephrine and pseudoephedrine? Do they work the same?
Both pseudoephedrine and phenylephrine are decongestants used to treat nasal congestion due to allergies, colds, sinus infections, etc. Since pseudoephedrine can be made into methamphetamine, the U.S. Senate passed a bill restricting its sale. Pseudoephedrine products can still be purchased in limited quantities, but identification and signatures are required. Some states also require a prescription for pseudoephedrine products.
Unfortunately, no studies have been done to confirm whether these two decongestants are equally effective. There are some differences in the way the drugs are absorbed by the body:
The intestines will absorb only about 38% of the amount of phenylephrine in one tablet, while pseudoephedrine is 100% absorbed.
The effects of phenylephrine do not last as long as pseudoephedrine. Therefore, phenylephrine needs to be taken every four hours, while pseudoephedrine can be taken every four to six hours.
On another note, I don't mind "coughing up" my drivers license, it is the exorbitant price that gets me. Pseudoephedrine used to be so inexpensive, and now even for the off brand it's anywhere from $1-$3 PER PILL! My doc put me on Allegra D for chronic sinusitis and migraine control, and $45 a month for an OTC med is just insane. I'll give you my drivers license, birth certificate, divorce decree, marriage certificate, SS #, even a DNA sample EVERY TIME, just drop the price to where it's a manageable amout for people.
When you try taking one and then the other you can usually feel a difference right away. My favourite cold formula contains pseudoephedrine and it brings a huge relief (you can really feel it starting to work) to my runny nose + watery, itchy eyes. It does make my mouth dry a bit too much, but I can go to work without sneezing all over my colleagues and customers.
I was tempted to try phenylephrine of course, but then one capsule didn't do anything. I tried to pair it with an antihistamine - again, it only stopped the sneezing and I had hard time at work. Pseudoephedrine wins and it's sad to see it disappear.
Pseudoephedrine works, phenylephrine is no better than placebo. Found that out with a web search after suffering through a sleepless night with a badly congested head & vastly exceeding recommended dose for phenylephrine.
FDA is willfully incompetent as usual in maintaining the charade oral phenylephrine does anything at all. It's inactivated my MAO inhibitors in the stomach & does nothing. If you want relief of your congestion, bite the bullet, cough up your drivers license & get the pseudoephedrine from behind the counter.
Signed an MD.
Pharmacists Leslie Hendeles and Randy Hatton of the University of Florida suggested in 2006 that oral phenylephrine is ineffective as a decongestant at the 10-mg dose used, arguing that the studies used for the regulatory approval of the drug in the United States in 1976 were inadequate to prove effectiveness at the 10-mg dose and safety at higher doses. Other pharmacists have expressed concerns over phenylephrine's effectiveness as a nasal decongestant, and other clinicians have indicated concern for regulatory actions that reduced the availability of pseudoephedrine.
A subsequent meta-analysis by the same researchers concluded that there is insufficient evidence for its effectiveness, though another meta-analysis published shortly thereafter by researchers from GlaxoSmithKline found the standard 10 mg dose to be significantly more effective than a placebo.Additionally, two studies published in 2009 examined the effects of phenylephrine on symptoms of allergic rhinitis by exposing sufferers to pollen in a controlled, indoor environment. Neither study was able to distinguish between the effects of phenylephrine or a placebo. Pseudoephedrine and loratadine-montelukast therapy were found to be significantly more effective than both phenylephrine and placebo.
The Food and Drug Administration has stood by its 1976 approval of phenylephrine for nasal congestion as the debate continues.
So basically they changed to formulation of Pseudoephedrine to Phenylephrine because Phenylephrine can't be used in producing Methamphetamine. I personally think that Pseudoephedrine is a much better drug but it's limited depending on where you live in the country. In Utah everything that has Pseudoephedrine in it has to be purchased through the pharmacy and you can only get so much of it. This is to prevent to making of Methamphetamine which I think is ridiculous. I hope this answers your question! Good Luck!
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