Single Injection of Etoricoxib Eased Acute Pain Rapidly in Indian Study

A single intramuscular injection of the painkiller etoricoxib was followed by a steep drop in reported pain intensity within an hour in a large observational study conducted across 68 sites in India, with most hospitalized patients reporting no pain at all by 24 hours. The study, published in the journal Drugs – Real World Outcomes, enrolled 418 adults who had already been prescribed the 90 mg intramuscular formulation as part of their routine care, and tracked their pain using a standard numeric rating scale at fixed intervals after the injection. Because the study had no comparison group, the researchers are careful to frame the results as an association observed in real-world practice rather than proof of the drug’s superiority over other analgesics.

The RAPID study, as it is known, was a multicenter, noncomparative, prospective observational trial run between 29 May 2024 and 20 March 2025. Treating physicians identified eligible patients during ordinary clinical encounters, and all eligible patients presenting during the recruitment period were consecutively enrolled after giving written informed consent, a design intended to limit selection bias. The decision to give the injection was made entirely at the physician’s discretion, independent of study participation, which the investigators say reflects genuine prescribing patterns. Each participant received a single deep intramuscular injection of etoricoxib 90 mg into the gluteal region, administered by a trained healthcare professional under aseptic precautions, and no repeat dosing was protocol-mandated during the observation window.

The cohort comprised 364 inpatients and 54 outpatients, with a mean age of 46.0 years and a predominantly male composition at 69.6 percent. Low back pain was the most common reason for the injection, accounting for 36.1 percent of cases, followed by acute pain of varied etiologies at 15.6 percent, joint pain at 12.0 percent, and postoperative pain at 9.1 percent. Eligible patients were adults presenting with acute painful conditions ranging from trauma and fractures to musculoskeletal exacerbations and inflammatory arthritis flares. Patients with contraindications listed in the prescribing information, including established cardiovascular disease, uncontrolled hypertension, severe renal or hepatic impairment, active gastrointestinal ulceration or bleeding, or known hypersensitivity to etoricoxib, were excluded.

Pain was measured with the Numeric Pain Rating Scale, an 11-point instrument running from zero for no pain to ten for the worst pain imaginable, which the researchers collapsed into four ordinal categories: none, mild, moderate, and severe. For inpatients, scores were recorded at baseline and then at 30 minutes, 60 minutes, and 4, 8, 12, and 24 hours after the injection. Outpatients were assessed only at baseline, 30 minutes, and 60 minutes. The primary endpoint was the change in score from baseline to 60 minutes for outpatients and from baseline to 24 hours for inpatients, and a clinically meaningful response was defined as an improvement of at least one pain severity grade at the 60-minute mark.

The inpatient results showed a rapid and sustained decline. Mean scores fell from 7.6 at baseline, where 73.4 percent of patients reported severe pain, to 5.4 at 30 minutes and 3.3 at 60 minutes, with further reductions to 1.8 at 4 hours, 0.9 at 8 hours, 0.4 at 12 hours, and 0.3 at 24 hours. All of these reductions were statistically significant compared with both baseline and the immediately preceding timepoint. By 24 hours, 88.7 percent of inpatients reported no pain at all, and more than 65 percent were pain free as early as 8 hours after the injection. A clinically meaningful categorical improvement at 60 minutes was seen in 90.6 percent of inpatients with severe baseline pain and 78.3 percent of those whose baseline pain was moderate.

Outpatients, who started with somewhat lower baseline pain at a mean of 6.1, also improved quickly. Their mean scores dropped to 2.4 at 30 minutes and 0.8 at 60 minutes, both statistically significant changes. At the one-hour mark, 70.4 percent of outpatients reported complete pain relief, 22.2 percent reported mild pain, and only 7.4 percent still had moderate pain, with no severe pain remaining. Every outpatient with severe baseline pain achieved at least a one-grade improvement, as did 97.3 percent of those starting with moderate pain. Because outpatient follow-up ended at 60 minutes, the longer-term trajectory documented in hospitalized patients could not be assessed in this group.

Physician impressions aligned with the numeric scores. Using the Global Physician Assessment of Analgesic Effectiveness, which categorizes responses as no change, mild, moderate, or marked improvement, treating physicians reported marked improvement in 52.2 percent of the overall cohort and moderate improvement in a further 30.1 percent, meaning 82.3 percent of patients were judged to have moderate or marked relief. Mild improvement was recorded in 12.9 percent and no improvement in 4.8 percent. The pattern was similar across care settings, with inpatients showing a mean assessment score of 3.3 on the four-point scale and outpatients 3.2, though the authors note that such physician-reported global judgments may be subject to assessment bias.

Tolerability findings were broadly reassuring but not unqualified. Injection-site reaction data were available for 411 patients, of whom 94.2 percent reported no reaction, and no reactions were reported among outpatients. However, injection-site pain at 60 minutes was reported by 46.9 percent of all 418 patients, and among the 178 patients with severity data available, most of this pain was mild or moderate, with severe injection-site pain in 7.9 percent of cases. Adverse event data were available for 360 patients, and events were reported by only 2.5 percent of them. No cardiovascular adverse events, hypertension episodes, edema, or fluid retention were reported by treating physicians during the observation period, though the authors explicitly acknowledge that the study was short-term, single-dose, and neither designed nor powered to evaluate cardiovascular outcomes. Notably, 16.7 percent of patients required rescue analgesics, such as oral paracetamol or oral NSAIDs, because of severe or inadequately controlled pain.

The findings sit within a broader evidence base for etoricoxib, a second-generation selective COX-2 inhibitor with roughly 106-fold greater selectivity for COX-2 over COX-1, a property intended to preserve analgesic efficacy while reducing the gastrointestinal toxicity associated with nonselective NSAIDs. Oral etoricoxib has been extensively studied; a Cochrane systematic review of single-dose oral etoricoxib in acute postoperative pain, covering six randomized trials and 1,214 patients, found that a 120 mg dose produced useful pain relief in 66 percent of patients compared with 12 percent on placebo. The drug’s long elimination half-life of approximately 22 hours, compared with roughly 5 to 6 hours for ketorolac and 1 to 2 hours for diclofenac, offers a pharmacological rationale for the sustained effect observed here, and the authors cite earlier Indian real-world studies, NICE and NICE 2.0, reporting consistent analgesic effectiveness and low rescue analgesia rates. The intramuscular formulation was developed using a solubilization technology that yields a stable, water-soluble preparation suitable for parenteral administration without the need for intravenous access, dilution, or infusion.

The study’s limitations are substantial and the authors lay them out plainly. The single-arm, noncomparative observational design precludes causal inference, so the observed pain reductions cannot be attributed solely to etoricoxib, and no conclusions about comparative efficacy can be drawn. Acute pain also has a well-recognized natural history of spontaneous resolution, meaning some of the improvement may reflect the natural trajectory rather than a treatment effect. Rescue analgesic use, recorded in 16.7 percent of patients, is a potential confounder whose timing relative to the 60-minute assessment was not captured. The predominantly male population may limit generalizability to women, and baseline cardiovascular risk factor data were not systematically reported. The authors conclude that intramuscular etoricoxib was associated with rapid and sustained pain reduction across a range of acute painful conditions in Indian clinical practice, and they call for randomized controlled trials with active comparators to establish its relative effectiveness and safety against other parenteral analgesic options.

Subject of Research: Real-world observational assessment of pain relief and tolerability after a single intramuscular etoricoxib injection in Indian adults with acute pain

Article Title: Prospective Real-World Assessment of Pain Relief with Injection-Based Delivery of Etoricoxib (RAPID Study)

Article References: Jha, S. S., Dhamangaonkar, A., Iyengar, R., Chakraverty, G., Rao, K. S., Mukherji, A., Muchhala, S., & Natarajan, V. (2026). Prospective Real-World Assessment of Pain Relief with Injection-Based Delivery of Etoricoxib (RAPID Study). Drugs – Real World Outcomes. https://doi.org/10.1007/s40801-026-00576-4

Image Credits: AI Generated

DOI: 10.1007/s40801-026-00576-4

Keywords: etoricoxib, intramuscular injection, acute pain, observational study, NSAIDs, COX-2 inhibitor, pain management, India, Numeric Pain Rating Scale, drug safety, real-world evidence, analgesia