Parecoxib sodium is a white or almost white crystalline powder with the chemical name sodium N-[4-(5-methyl-3-phenyl-1,2-oxazol-4-yl)benzenesulfonyl]propanecarboximidate which is freely soluble in water, methanol, N,N-dimethylformamide. Parecoxib sodium is an amide prodrug of the cyclooxygenase II (COX-2) selective, non-steroidal anti-inflammatory drug (NSAID) valdecoxib, with anti-inflammatory, analgesic, and antipyretic activities. The structure of parecoxib sodium is showed in figure 1.
Fig. 1 Structure of parecoxib sodium
Application in the treatment of postoperative pain
- Mechanism of action
Parecoxib sodium is approved through much of Europe for short term postoperative pain control.
Upon intravenous or intramuscular administration, parecoxib is hydrolyzed by hepatic carboxyesterases to its active form, valdecoxib. Valdecoxib selectively binds to and inhibits COX-2. This prevents the conversion of arachidonic acid into prostaglandins, which are involved in the regulation of pain, inflammation, and fever. This NSAID does not inhibit COX-1 at therapeutic concentrations and, therefore, does not interfere with blood coagulation. Figure 2 shows the schematic of NSAID mechanism of action.
Fig. 2 Schematic of NSAID mechanism of action
COX-1, a constitutive enzyme, plays a major role in the release of PG to regulate hemostasis. COX-2, an inducible enzyme, releases PG that mediates pain, inflammation, and fever. Nonselective NSAIDs inhibit both forms of COX [1].
When given at the recommended doses for management of acute pain, the onset of analgesia was 7–14 minutes and reached a peak effect within 2 hours. After a single dose, the duration of analgesia was dose and clinical pain model dependent and ranged from 6 to greater than 24 hours.
- Comparation of parecoxib sodium between morphine in analgesia
A total of 32 patients, including 26 males and 6 females, were enrolled. Eighteen patients received (intravenous) IV parecoxib sodium as an analgesic whereas 14 patients received IV morphine. Patients with a bone fracture were equal in number for both groups. Table 1 shows result [2].
| Study drug | Time (minutes) | Mean (SD) | Estimated marginal mean (95% CI) | P value |
| Parecoxib sodium | 0 | 7.8 (1.3) | 7.09, 8.41 | |
| 5 | 5.7 (2.2) | 4.77, 6.71 | ||
| 15 | 4.7 (2.3) | 3.66, 5.64 | ||
| 30 | 3.9 (2.3) | 2.93, 4.77 | ||
| Morphine | 0 | 7.1 (1.3) | 6.38, 7.88 | 0.095 |
| 5 | 4.5 (1.7) | 3.44, 5.65 | ||
| 15 | 3.1 (1.6) | 1.94, 4.19 | ||
| 30 | 2.0 (1.4) | 0.99, 3.09 |
Table 1. Comparison of mean numeric rating scale (NRS) between patients treated with IV parecoxib sodium or IV morphine based on time (SD = standard deviation, CI = confidence interval, p value = repeated measure analysis of variance)
The mean numeric rating scale (NRS) for patients that were treated with IV morphine were 7.1 at 0 minutes, 4.5 at 5 minutes, 3.1 at 15 minutes, and 2.0 at 30 minutes. Mean NRS for patients who received IV parecoxib were 7.8 at 0 minutes, 5.7 at 5 minutes, 4.7 at 15 minutes, and 3.9 at 30 minutes.
There was non-significant trend toward superiority of IV morphine over IV parecoxib. Looking at its effectiveness and the lack of opioid-related side-effects, the usage of IV parecoxib sodium may be extended further to a variety of cases in the emergency department.
