Pharmacy Division Ramathibodi Hospital


News 22/12/2544

Clinical doses of ibuprofen counteract aspirin's cardioprotective effects, at least in vitro.

While there is no cure for the common cold, antiseptic skin cleansers that contain salicylic acid or pyroglutamic acid may help prevent hand-to-hand transmission of rhinovirus.

Ibuprofen Prevents Platelet Inhibition by Aspirin

NEW YORK (Reuters Health) Dec 19 - Clinical doses of ibuprofen counteract aspirin's cardioprotective effects, at least in vitro, according to a report in the December 20th issue of the New England Journal of Medicine.

Dr. Garret A. FitzGerald and colleagues, of the University of Pennsylvania School of Medicine in Philadelphia, first conducted a 6-day crossover study with single daily doses of aspirin 81 mg in combination with ibuprofen 400 mg, acetaminophen 1000 mg, or rofecoxib 25 mg. Each treatment combination involved a sample of five subjects.

Measurements of serum thromboxane B-2 were used to assess platelet cyclooxygenase-1 (COX-1) activity. When aspirin was given 2 hours before ibuprofen, serum thromboxane B-2 was 98% inhibited for up to 24 hours after dosing on day 6. When dosing was reversed, with ibuprofen administered 2 hours before aspirin, inhibition was 97% at 2 hours after dosing, but had fallen to 53% by 24 hours after the final dose. Pretreatment with acetaminophen or with rofecoxib failed to alter aspirin's antiplatelet effect.

Findings were similar for platelet aggregation, which was reversibly inhibited when subjects took ibuprofen, but not acetaminophen or rofecoxib, before aspirin.

Dr. FitzGerald's team then conducted a parallel-group study, in which subjects took aspirin 2 hours before the first of three daily doses of ibuprofen or of two daily doses of delayed-release diclofenac 75 mg. The investigators found that the effects of daily low-dose aspirin on platelets were blocked by the prolonged use of three daily doses of ibuprofen, even when the aspirin was administered first. Diclofenac produced no such interaction.

In an editorial, Dr. Leslie J. Crofford describes as "interesting and important" the hypothesis of the Philadelphia group that some nonsteroidal antiinflammatory drugs (NSAIDs) could interfere with the antiplatelet effect of aspirin by occupying the hydrophobic channel of platelet COX-1.

Dr. Crofford, of the University of Michigan an Ann Arbor, notes, however, that their studies were performed ex vivo and that they tested platelet function in isolation. "In vivo and clinical studies assessing the combination of low-dose aspirin with NSAIDs, coxibs, or acetaminophen will be required to determine the cardiovascular implications of the interactions among these drugs," the commentator suggests.

Dr. Crofford concludes that if these findings are confirmed as clinically important, physicians prescribing a combination of aspirin and NSAID will need to consider their interaction.

N Engl J Med 2001;345:1809-1817, 1844-1846.

Antiseptic Skin Cleansers May Prevent Rhinovirus Transmission

CHICAGO (Reuters Health) Dec 17 - While there is no cure for the common cold, antiseptic skin cleansers that contain salicylic acid or pyroglutamic acid may help prevent hand-to-hand transmission of rhinovirus.

These types of cleansers are virucidal on contact and demonstrate anti-rhinovirus activity that can persist for several hours after application, according to study findings presented here Monday at the 41st Annual Interscience Conference on Antimicrobial Agents and Chemotherapy.

Dr. Ronald B. Turner, from the Medical University of South Carolina at Charleston, and colleagues performed two studies to investigate the efficacy of antiseptic skin cleansers in interrupting the transmission of rhinovirus infections.

In both studies, the hands of volunteers were challenged with rhinovirus after being washed with a skin cleanser. The subjects were then instructed to make intentional conjunctiva and nasal mucosa contact with one hand.

In the first study, the hands of 85 subjects were challenged with rhinovirus 15 minutes after being washed with a salicylic acid, pyroglutamic acid, or control solution. Significantly fewer positive hand cultures were noted among salicylic acid-treated subjects than among control subjects. Both treatment groups had a significantly lower rhinovirus infection rate than the control group, the researchers note.

In the second study, the researchers determined the anti-rhinovirus activity of a pyroglutamic acid cleanser up to 3 hours after washing. At all time points up to 3 hours, pyroglutamic acid-treated subjects had significantly fewer positive hand cultures than control subjects. The proportion of subjects who became infected, however, did not differ significantly between the groups.

"This is the first time that the virucidal activity of these compounds has been evaluated," Dr. Turner told Reuters Health. "Prior studies have only examined the antibacterial effects," he added. "In fact, if I remember correctly, pyroglutamic acid is actually marketed as a moisturizer; it wasn't even considered to be an antimicrobial agent," he said.

"Our studies indicate that these compounds have residual anti-rhinovirus activity that extends, in some cases, up to 3 hours after application," Dr. Turner stated. "Some commercially available skin cleansers already contain these compounds," he pointed out.

However, he warns that "the current findings really don't prove anything in the natural setting." Further studies are needed "to prove that these agents can actually prevent transmission of rhinovirus," he added.

Back To Top © 2001-2009 RxRama ---- All rights reserved.