Safety of multiple-dose intravenous acetaminophen in adult inpatients.

Background: Intravenous (IV) acetaminophen provides rapid and effective analgesia in the postoperative and inpatient settings. The utility and efficacy of acetaminophen is well established; however, due to chronic excessive dosing of over-the-counter acetaminophen products and prescription opioid combination products resulting in the potential for hepatic toxicity, concerns remain about acetaminophen safety. In order to evaluate the safety of IV acetaminophen 1,000mg q6h or 650mg q4h with repeated dosing for 5 days, a randomized, open-label study assessed the safety and tolerability of repeated doses used to treat acute pain or fever in 213 adult inpatients was conducted.

Methods: Subjects were randomized (3:3:1) to receive IV acetaminophen (1,000mg q6h or 650mg q4h) or standard-of-care treatment for pain or fever. Safety was assessed according to spontaneous reports of adverse events (AEs) and clinically meaningful changes from baseline laboratory parameters.

Results: Overall, IV acetaminophen was shown to be safe and well tolerated in adult inpatients when given as repeated doses for up to 5 days. Owing to the comorbidities in the study population, the frequency of AEs reported was high. However, the majority of treatment-emergent adverse events (TEAEs) were unrelated to treatment, and only 8% of the study population withdrew because of TEAEs. No major hepatic issues associated with IV acetaminophen warranted concern, and most hepatic events were likely related to underlying medical conditions or recent trauma/surgery.

Conclusions: Consistent with the tolerability and safety results, both treatment groups (1,000mg q6h and 650mg q4h) demonstrated statistically significantly better ratings for the Subject Global Evaluations for the level of satisfaction with side effects related to study treatments as compared with the control group. The findings from this trial support the use of IV acetaminophen as a safe therapy in adult patients.