Dose evaluation of intravenous metamizole (dipyrone) in infants and children: a prospective population pharmacokinetic study

Analgesic use and favourable patient-reported outcome measures after paediatric surgery: an analysis of registry data

BACKGROUND

Pain after paediatric appendectomy and tonsillectomy is often undertreated. Benchmarking of hospitals could reveal which measures are associated with improved patient- or parent-reported pain-related outcomes.

METHODS

A total of 898 anonymised cases from 11 European hospitals participating in PAIN OUT infant were analysed. The children completed a questionnaire on patient-reported outcomes (PROs) 24 h after surgery. According to a composite PRO measure, including pain intensity and pain-related interference, hospitals were allocated to Group I (favourable results), II (average results), and III (unfavourable results). Benchmarking of hospital groups was performed investigating process variables (dosing of non-opioid analgesics, opioids, and dexamethasone) associated with PROs, side-effects, and children's perception of care. Variables associated with PROs were analysed using multinomial regression analysis with the PRO score-related hospital group as a dependent variable (estimated odds ratios [OR], 95% confidence interval [CI]).

RESULTS

During the first 24 h after surgery, 1.2 (1.1-1.3) full daily doses of non-opioid analgesics (non-steroidal anti-inflammatory drug [NSAID], paracetamol, metamizole) were administered in group I and 0.7 (0.6-0.8) in group III (P<0.001). Intraoperative dexamethasone was administered to 70.1 and 52.6% of the children in Group I and Group III, respectively (P<0.001). A lower number of full daily doses of non-opioid analgesics: 0.22 [0.15-0.31]), less dexamethasone (0.49 [0.33-0.71]), fewer non-opioid analgesics before the end of surgery (0.37 [0.22-0.62]) and higher opioid doses were associated with hospital allocation to group III vs group I (Nagelkerke's R²=0.433).

CONCLUSIONS

The results indicated substantial deficits in the concept, application, and dosing of analgesics in paediatric patients after surgery. Timely administration of adequate analgesic doses can easily be introduced into daily clinical practice.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov NCT02083835.

Pharmacometric Analysis of Intranasal and Intravenous Nalbuphine to Optimize Pain Management in Infants

Objectives

The objective of this pharmacometric (PMX) study was to (i) characterize population pharmacokinetics (PPK) and exposure-pain response associations following intranasal (0.1 mg/kg) or intravenous (IV, 0.05 mg/kg) administration of nalbuphine, with the goal to (ii) evaluate strategies for optimized dosing and timing of painful interventions in infants 1-3 months old.

Methods

PPK analysis of nalbuphine serum concentrations, prospectively collected 15, 30, and between 120 and 180 min post-dose, utilizing the software package Monolix. The final PPK model was applied to derive individual time-matched concentration predictions for each pain assessment (Neonatal Infant Pain Score, NIPS) after establishment of venous access and urinary catheterization or lumbar puncture. Drug exposure-pain response simulations were performed to evaluate potential benefits of higher doses with respect to a previously proposed target concentration of 12 mcg/L (efficacy threshold).

Results

Thirty-eight of 52 study subjects receiving nalbuphine had at least one concentration measurement and were included in the pharmacometric analysis. A two-compartment model with allometric scaling was applied to describe population PK data, with intranasal bioavailability estimated to be 41% (95%CI: 26-56%). Model-based simulations showed that the proposed efficacy threshold (12 mcg/L) is expected to be exceeded with an IV dose of 0.05 mg/kg for 6 min, with 0.1 mg/kg for 30 min and with 0.2 mg/kg for 80 min. This efficacy threshold is not achieved with intranasal doses of 0.1 and 0.2 mg/kg, whereas an intranasal dose of 0.4 mg/kg is expected to exceed such threshold for 30 to 100 min.

Conclusion

This PMX study confirmed that bioavailability of intranasal nalbuphine is close to 50%. Exposure-pain response simulations indicated that an intranasal dose of 0.4 mg/kg is required to provide a comparable pain control as achieved with an IV dose of 0.1-0.2 mg/kg. The optimal time window for painful procedures appears to be within the first 30 min after IV administration of 0.1 mg/kg nalbuphine, whereas such procedures should be scheduled 30 min after an intranasal dose of 0.4 mg/kg nalbuphine. Additional clinical studies are warranted to confirm these PMX based recommendations and to further optimize pain management in this vulnerable infant population.

Metamizole Use in Children: Analysis of Drug Utilisation and Adverse Drug Reactions at a German University Hospital between 2015 and 2020

BACKGROUND

Metamizole use is controversially discussed due to its potentially serious adverse drug reactions (ADRs). In Germany, however, it remains a popular analgesic and antipyretic drug.

OBJECTIVE

The aim of this study was to discuss the safety profile of metamizole in children by analysing the inpatient prescription patterns and presenting the metamizole-related ADRs at a paediatric hospital between 2015 and 2020.

METHODS

Metamizole utilisation data were retrospectively analysed from electronic medical records. ADRs were prospectively recorded via the hospital's stimulated reporting system and analysed accordingly. Patients aged < 18 years admitted to one of the general wards of the department of paediatrics and adolescent medicine of a German university hospital between June 2015 and May 2020 who received at least one drug therapy within their inpatient stay were included in the analysis. Causality of ADRs was rated according to the World Health Organisation causality assessment.

RESULTS

In 31.7% (3759/11,857) of the inpatient stays of 7809 patients, metamizole was administered. Metamizole exposure was highest in adolescents (37.9%) and lowest in newborns (9.9%). Overall, metamizole was administered parenterally in about 90%. Three cases of agranulocytosis, one allergic shock and one rash with possible or higher causality to metamizole treatment were reported. Three of these occurred prior to hospitalisation. All patients recovered without remaining harm.

DISCUSSION

Metamizole is commonly used in paediatric inpatients in Germany. Serious ADRs occur but rarely. Continuous monitoring of drug therapy through, for example, stimulated reporting systems ensures that serious ADRs are detected, and appropriate interventions can be introduced.