Y a t-il un risque à prescrire du paracétamol chez des malades atteints d’hépatopathies aiguës ou chroniques ?

Hepatotoxicity risk factors and acetaminophen dose adjustment, do prescribers give this issue adequate consideration? A French university hospital study

BACKGROUND

The hepatotoxicity of acetaminophen is recognised worldwide. Unfavourable prognoses relating to overdose include liver transplantation and/or death. Several hepatotoxicity risk factors (HRFs) should motivate the adjustment of acetaminophen daily intake (to < 4 g/day): advanced age, weight < 50 kg, malnutrition, chronic alcoholism, chronic hepatitis B and C and HIV infection, severe chronic renal failure and hepatocellular insufficiency.

METHOD

Over a 7-day period in Rennes University Hospital in December 2017, using DxCare® software, with an odds ratio estimation, we analysed all acetaminophen prescriptions, to assess to what extent the presence of HRFs altered the prescribers' choice of acetaminophen dose (< 4 g/day versus 4 g/day).

RESULTS

Among 1842 patients, considering only the first acetaminophen prescription, 73.7% were on 4 g/day. Almost half this population had at least 1 HRF. Whereas around 80% of the prescriptions in the < 4 g/day group were for patients with at least 1 HFR, only 53% of the prescriptions in the 4 g/day group concerned patients without HFRs (p < 0.001). Age > 75 and low weight were associated with the prescriber's choice of dose. Neither chronic alcoholism nor hepatocellular insufficiency influenced the acetaminophen doses prescribed.

CONCLUSION

Considering the widespread use of acetaminophen and its favourable safety profile compared with other analgesic drugs, it appears urgent to remind prescribers of the maximum daily dose recommendations for acetaminophen for patients with HRFs, especially those with chronic alcoholism and hepatocellular insufficiency.

Median effective dose (ED₅₀) of paracetamol and morphine for postoperative pain: a study of interaction

BACKGROUND

Paracetamol is widely used to treat postoperative pain and is well known for its morphine-sparing effect. Therefore, the effect of morphine-paracetamol combination can be synergistic, additive, or infra-additive. The primary aim of our study is to define the median effective analgesic doses (ED₅₀s) of paracetamol, morphine, and the combination of both. Also, the nature of the interaction for postoperative pain after moderately painful surgery using an up-and-down method and isobolographic analysis was determined.

METHODS

Ninety patients, undergoing moderately painful surgery, were included in one of the three groups. Determination of the median ED₅₀s was performed by the Dixon and Mood up-and-down method. Initial doses were 1.5 g and 5 mg, with dose adjustment intervals of 0.5 g and 1 mg, in the paracetamol and morphine groups, respectively. The initial doses of paracetamol and morphine were 1.5 g and 3 mg, in the paracetamol-morphine combination group with dose adjustment intervals of 0.25 g for paracetamol and 0.5 mg for morphine. Analgesic efficacy was defined as a reduction to or <3 on a 0-10 numeric rating scale, 45 min after the beginning of drug administration. Isobolographic analysis was used to define the nature of their interaction.

RESULTS

The median ED₅₀s of paracetamol and morphine were 2.1 g and 5 mg, respectively. The median ED₅₀ of the combination was 1.3 g for paracetamol and 2.7 mg for morphine.

CONCLUSIONS

Our study showed that the combination of the paracetamol and morphine produces an additive analgesic effect. Clinical trial registration NCT01366313.