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Postoperative analgesia using diclofenac and acetaminophen in children
Jacqueline A Hannam1, Brian J Anderson, Murali Mahadevan
1Department of Anaesthesiology, University of Auckland, Auckland, New Zealand.
Insights
Combining diclofenac and acetaminophen offers effective pain relief in children. This combination allows for similar analgesia using lower doses of each drug, improving pediatric pain management.
Area of Science:
- Pharmacology
- Pediatric Medicine
- Pain Management
Background:
- Current pediatric diclofenac dosing relies on adult data.
- Recommended oral diclofenac dose for children (1-12 years) is 1.0 mg·kg⁻¹.
- The analgesic efficacy of combined diclofenac and acetaminophen in children is not well-established.
Purpose of the Study:
- To evaluate the analgesic effects of combined diclofenac and acetaminophen in children.
- To determine optimal dosing for pediatric pain management using this combination therapy.
Main Methods:
- Randomized controlled trial involving children undergoing tonsillectomy.
- Administration of varying doses of diclofenac (0.1-2.0 mg·kg⁻¹) with or without acetaminophen.
- Pharmacokinetic and pharmacodynamic modeling to assess drug effects and interactions.
Main Results:
- Drug effects were found to be additive, with diclofenac showing faster onset of analgesia.
- A combination of diclofenac 1.0 mg·kg⁻¹ and acetaminophen 15 mg·kg⁻¹ provided analgesia equivalent to acetaminophen 30 mg·kg⁻¹ alone.
- The hazard of study dropout was significantly related to pain levels.
Conclusions:
- Combination therapy with diclofenac and acetaminophen can achieve effective analgesia in children.
- Lower doses of both diclofenac and acetaminophen can be used in combination for similar pain relief.
- This approach offers a strategy for optimizing pediatric pain management.
Background:
Diclofenac dosing in children for analgesia is currently extrapolated from adult data. Oral diclofenac 1.0 mg·kg(-1) is recommended for children aged 1-12 years. Analgesic effect from combination diclofenac/acetaminophen is unknown.
Methods:
Children (n = 151) undergoing tonsillectomy (c. 1995) were randomized to receive acetaminophen elixir 40 mg·kg(-1) before surgery and 20 mg·kg(-1) rectally at the end of surgery with diclofenac suspension 0.1 mg·kg(-1) , 0.5 mg·kg(-1) , or 2.0 mg·kg(-1) before surgery or placebo. A further 93 children were randomized to receive diclofenac 0.1 mg·kg(-1) , 0.5 mg·kg(-1) , or 2.0 mg·kg(-1) only. Postoperative pain was assessed (visual analogue score, VAS 0-10) at half-hourly intervals from waking until discharge. Data were pooled with those from a further 222 children and 30 adults. One-compartment models with first-order absorption and elimination described the pharmacokinetics of both medicines. Combined drug effects were described using a modified EMAX model with an interaction term. An interval-censored model described the hazard of study dropout.
Results:
Analgesia onset had an equilibration half-time of 0.496 h for acetaminophen and 0.23 h for diclofenac. The maximum effect (EMAX ) was 4.9. The concentration resulting in 50% of EMAX (C50 ) was 1.23 mg·l(-1) for diclofenac and 13.3 mg·l(-1) for acetaminophen. A peak placebo effect of 6.8 occurred at 4 h. Drug effects were additive. The hazard of dropping out was related to pain (hazard ratio of 1.35 per unit change in pain). Diclofenac 1.0 mg·kg(-1) with acetaminophen 15 mg·kg(-1) achieves equivalent analgesia to acetaminophen 30 mg·kg(-1) .
Conclusions:
Combination therapy can be used to achieve similar analgesia with lower doses of both drugs.
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