Case study on Zyrtec-D

I can't remember the last time I woke up at six in the morning. This is the first in a very very long time. =P

I was very surprised. Then it suddenly struck me: pseudoephedrine is pseudo-ephedrine. Haha. I guess I didn't realise that before because I knew the name pseudoephedrine before I knew ephedrine.

And so the reason for my insomnia became apparent. Ephedrine has a high log P value and therefore can diffuse across my blood-brain barrier and rob me of my sleepiness.

So I decided to read up about my cold medication: Zyrtec-D (cetirizine 5mg, pseudoephedrine 120mg)

Let me present my case here..

Before that, a little background info.

Clinical scenario:

Ms FWC, a 22-year old female was prescribed Zyrtec-D for a cold she was having since 5 days ago. She took her first tablet yesterday at 6pm and began to feel drowsy later in the night. She then slept and woke up at 6am complaining of being unable to resume her sleep. It is not a common practice for Ms FWC to wake up at such an hour.

My case:

ZYRTEC-D 12 HOUR™ (cetirizine hydrochloride 5 mg and pseudoephedrine hydrochloride 120 mg) Extended Release Tablets for oral administration contain 5 mg of cetirizine hydrochloride for immediate release and 120 mg of pseudoephedrine hydrochloride for extended release in a bilayer tablet.

The active ingredient cetirizine which is an antihistamine may cause somnolence (13.7% in patients compared with 6.3% in placebo patients). Pseudoephedrine, a decongestant, has a high log P value and can diffuse across the blood-brain barrier to cause imsomnia. Since cetirizine is released first, patients may initially experience an increase in drowsiness; the insomniac effects of pseudoephedrine are experienced much later due to its extended release. After taking the medication 12 hours later, Ms FWC is experiencing the full effect of pseudoephedrine. Since pseudoephedrine, similiar to its structural isomer ephedrine, is not a catecholamine, it is not degraded by COMT and is potentially long-acting. Therefore, Ms FWC can expect to remain in a state of wakefulness for some time. However, Ms FWC may experience dizziness and light-headedness due to lack of sleep.

Ms FWC may also complain of pharyngitis and sinusitis. It is recommended that she drink more water.

Ms FWC should be advised that there is an increased risk of accidental injury to herself when on this medication. Statistics are 1.1% in patients and 0.4% in placebo patients.

On a side note, I discovered that academicians in my field have a lame sense of humour.

Definition of Somnolence
Somnolence: Sleepiness, the state of feeling drowsy, ready to fall asleep. A person experiencing somnolence is somnolent and is acting somnolently.
Somnolence, somnolent, and somnolently go back to the Latin "somnus" meaning (please don't yawn) "sleep."

excerpt from http://www.rxlist.com/script/main/art.asp?articlekey=13097

I did a double-take on that. I think I saw 'gagak's cawing happily and flying past my screen.

I wonder if hallucination is one of the adverse effects Pfizer forgot to mention. Hmm.