Propofol is the most popular IV anaesthetic agent used for induction, however one of its known side effects is causing pain on injection, the gold standard method in preventing this pain is using lidocaine prior to injecting propofol. multiple drugs have been investigated to reduce the aforementioned pain, however there has been no study comparing lidocaine to parecoxib, an NSAID.

Propofol is the most popular drug used for induction of anaesthesia. without prophylaxis, 60 to 70% of patients are affected by pain upon injection, with varying degrees of severity. The specific mechanism triggering pain is undetermined, but it is thought to be due to triggering of kallikrein-kinin cascade when it is injected.

Many strategies have been investigated to reduce the severity of this pain, with the most effective being the use of a large vein to deliver the drug, combined with pretreatment using lidocaine with venous occlusion to allow it to anaesthetize the vein locally. This approach has been shown in a large meta-analysis to be the gold standard for reducing pain caused by propofol injection, achieving up to an 80% reduction in incidence. However, this method is not widely used clinically, probably due to the extra time required to anaesthetize the vein and applying a tourniquet. On the other hand, using lidocaine as a pre- treatment or mixed with propofol has been shown to reduce pain on injection.

Multiple other agents have been investigated with the aim of preventing the pain caused by propofol injection, such as opioids and ketamine. Non-steroidal Anti inflammatory Drugs (NSAIDs) have also been studied, with the rationale that reducing prostaglandin production caused by the suggested cascade above. These medications are usually used as part of the multimodal analgesia delivered to the patient to prevent intraoperative and postoperative pain, if given prior to propofol, they may have the added benefit of reducing the pain caused by injecting propofol.

Parecoxib, a selective COX-2 inhibitor in the NSAIDs class, has been investigated recently in trails to prevent pain on injection caused by propofol, where a prospective Randomised controlled trial showed that a dose of 40 mg was effective in reducing the frequency and the severity of the pain, where the incidence of pain was only 26%, compared to 58% in the placebo group. Furthermore non of the patients in this group reported moderate or severe pain. In the same study, a 20 mg Dose was only shown to reduce the severity of pain and not the incidence.

The Investigators propose this study to compare the two interventions as no previous study has investigated them in the same setting.

Objective of the study.

To compare the efficacy of intravenous parecoxib versus lidocaine in reducing pain during propofol injection in adult ASA I-II patients.

Inclusion Criteria:

• Adult patients, ≥18 years
• ASA grading I-II
• Patients undergoing elective surgical procedures across all surgical specialties.
• Can speak Arabic or English

Exclusion Criteria:

• Difficulty in communicating.
• Liver Cirrhosis patients
• Renal failure or creatinine clearance (CrCl) ≤ 10umol/L,
• Known Lidocaine, parecoxib and/or propofol allergy.
• patients who are not using propofol for an induction.
• Any known contraindication to propofol, parecoxib or lidocaine. (this will include renal failure or cirrhosis of the liver as noted above)
• Patients refusing to be involved in the study.
• ASA(American society of anaesthesia) grading 3-6.
• Any patient that IV access cannot be established in the dorsum of the hand.
• Pregnant women.
• Patients with chronic pain disorders.
• Patients who received any form of analgesia within the last hour.