Background: Aspirin (acetylsalicylic acid) and acetaminophen (paracetamol) are frequently used to treat fever and other symptoms of upper respiratory tract infection (URTI). Both are available over the counter for use at the standard recommended doses of 500 and 1000 mg per single use.
Objective: This study investigated the efficacy, safety profiles, and tolerability of aspirin 500 and 1000 mg and acetaminophen 500 and 1000 mg compared with placebo in adult patients with acute febrile URTI of suspected viral origin.
Methods: This was a multicenter, randomized, double-blind, double-dummy, placebo-controlled, parallel-group trial conducted in Ukraine and Russia. Patients with URTI and acute fever of > or =38.5 degrees C received a single dose of aspirin 500 or 1000 mg, acetaminophen 500 or 1000 mg, or matching placebo. Oral body temperature was measured in the clinic at specified time points up to 6 hours after dosing. The intensity of other symptoms of URTI was rated by patients at baseline and at 2, 4, and 6 hours after dosing (scale from 0 = none to 10 = severe). The primary efficacy measure was the AUC for the change in orally measured body temperature from the time of treatment (baseline) to 4 hours after dosing. Secondary outcome measures included the change in body temperature from baseline to specified time points between 0.5 and 6 hours after dosing, the difference between baseline and the lowest measured body temperature, the time to the lowest measured body temperature, and the intensity of other symptoms of URTI (ie, headache, sinus sensitivity to percussion, sore throat, achiness, and feverish discomfort). Tolerability was monitored by recording of adverse events.
Results: Three hundred ninety-two patients were enrolled (78 in both aspirin groups, 79 in both acetaminophen groups, 78 in the placebo group). Demographic and baseline characteristics were comparable in the 5 groups; 51% of patients were male, with a mean age of 37.4 years and a mean body weight of 74.3 kg. The AUC values for the change in body temperature 0 to 4 hours after dosing were 3.18 (95% CI, 2.78-3.57) for aspirin 500 mg, 4.26 (95% CI, 3.84-4.68) for aspirin 1000 mg, 3.13 (95% CI, 2.77-3.49) for acetaminophen 500 mg, 4.11 (95% CI, 3.73-4.49) for acetaminophen 1000 mg, and 0.76 (95% CI, 0.38-1.13) for placebo. In terms of the primary efficacy variable, all active treatments were significantly superior to placebo (P < 0.001, 1-sided t test), with no significant differences between them. Reductions in body temperature were significantly greater with the 1000-mg doses of both active treatments compared with the 500-mg doses (P< 0.001, 1-sided t test). The mean maximum temperature reductions were 1.32 degrees C, 1.25 degrees C, 1.67 degrees C,1.71 degrees C, and 0.63 degrees C in the respective treatment groups. Significant reductions were seen in the mean intensity of headache, achiness, and feverish discomfort with all active treatments at most time points (P < 0.001), but not in sinus sensitivity to percussion or sore throat. All treatments were equally well tolerated, and no clinically significant adverse events occurred.
Conclusions: In this single-dose study, aspirin 500 and 1000 mg and acetaminophen 500 and 1000 mg were more effective against fever and other symptoms of URTI than placebo. Both active treatments showed dose-related efficacy, and there was no significant difference between equal doses of the 2 agents. Safety profiles and tolerability were also comparable between treatments.