Acetaminophen for Chronic Pain in Hysterectomy
Condition: Abdominal Hysterectomy (& Wertheim)
MeSH terms: Chronic Pain
Study type: Interventional
Phase: Phase 4

Summary: 
      The investigators hypothesized that 1 mg of acetaminophen 4 times per day for 3 days prevent
      chronic pain in hysterectomy patients.
    

Detailed description: 
      The most appropriate expression of the pain is "an unpleasant sensory and emotional
      experience associated with actual or potential tissue damage, or described in terms of such
      damage" (IASP,2008) (1). When pain lasts longer than 3 months or beyond the time when an
      acute injury would be expected to have healed, the patient's presentation becomes more
      complex, often, not surprisingly, with more psychological features. These include complaints
      of poor or non-refreshing sleep, tiredness, depression and poor concentration. Pain at this
      stage is often said to be "chronic" (2). Chronic pain is not only a common problem but also a
      significant and increasing public health burden in virtually all developed countries (3).
      Hysterectomy is one of the most common surgical procedures in women. Recent studies have
      recognized that there is a 20-40% incidence of chronic post-surgical pain after hysterectomy
      surgery (4)(5)(6). Effective pain management is an important component of postsurgical care.
      Many patients, however, continue to experience inadequate pain relief (7) Despite all
      analgesic strategies, in the postoperative periods 80% of patients still suffer from moderate
      to severe pain (8).

      The ideal analgesic has some properties like rapid and effective pain relief, minimal adverse
      effects, and minimal impact on major organ systems or no interaction with other pharmacologic
      agents. Opioids are still good choice for postoperative pain but has dose dependent adverse
      effects and negative postoperative outcomes (9)(10). Nonopioid analgesics are commonly used
      alone or as adjuncts to opioid-based analgesia to treat moderate to severe pain.
      Perioperative administration of acetaminophen with nonsteroidal antiinflammatory drugs
      (NSAIDs) has been advocated to provide "multimodal" or "balanced" analgesia that decreases
      opioid dose requirements and may reduce associated adverse events while reducing postsurgical
      pain intensity ( 9)(11). Acetaminophen is superior to the other analgesics because of safety
      and analgesic profile. At the same time it has less contraindications and drug interactions
      with the others. Acetaminophen act by selectively inhibiting the release of prostaglandins
      within the central nervous system as well as having some peripheral analgesic effect (12).
      Rarely overdose use can induce hepatoxicity (13).

      While providing fast and significant pain relief as well as a significant morphine-sparing
      effect,(14) (15). it is not associated with the increased incidence of nausea, vomiting, and
      respiratory depression observed with opioids or the deleterious gastrointestinal,
      hematologic, and renal effects associated with NSAIDs and cyclooxygenase (COX)-2 inhibitors
      (16).

      Several international guidelines (EULAR, ACR) and influential reviews recommend the use of
      paracetamol as the first-line analgesic of choice for the management of chronic pain, as it
      provides cost-effective analgesia without the risks associated with NSAID use, particularly
      in the elderly. Based on currently available data, the use of alternative analgesics, such as
      tramadol and opioids, either alone or in combination with paracetamol, is warranted in those
      patients whose pain does not respond to nonnarcotic analgesics. While these recommendations
      are based on a vast amount of clinical data, they do not account for individual patient
      responses (17).

      Paracetamol is rapidly absorbed from immediaterelease formulations, with maximum
      concentrations in plasma typically occurring between 0.25 and 2.0 hours, and an onset of
      action within about 30 minutes (18). Because the terminal elimination phase half-life of
      paracetamol in plasma is short, in the region of 1.9-2.5 hours after a therapeutic dose,(19)
      the recommended time between doses is 4-6 hours, resulting in a 4-times daily dosing
      schedule.

      The investigators hypothesised that postoperative treatment with paracetamol with repeated
      doses of 1 g in comparison of placebo in hysterectomy patients with moderate or severe pain
      would decrease analgesics consumption perioperatively and the incidence of chronic pain
      associated with abdominal hysterectomy.
    

Intervention name(s): Acetaminophen; Isotonic
Intervention type(s): Drug; Drug
Intervention description(s): 100 ml iv, 4 times a day for 72 hours; 100 ml iv, 4 times a day for 72 hours
Other intervention name(s): Parol
Intervention MeSH terms: Acetaminophen
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Care Provider, Investigator)
Primary purpose: Treatment
Keywords: Abdominal Hysterectomy, Acetaminophen, chronic pain