Plasma paracetamol concentrations and pharmacokinetics following rectal administration in neonates and young infants.

BACKGROUND: Despite widespread use in children pharmacokinetic data about paracetamol are relatively scarce, not the least in the youngest age groups. This study aimed to describe plasma paracetamol concentrations and pharmacokinetics of a single rectal paracetamol dose in neonates and young infants. METHODS: Perioperatively, 17 neonates and infants < or =160 days of age received one rectal paracetamol dose (mean 23.9 mg/kg (+/-4.2 mg/kg)). Blood samples were drawn at 60, 120, 180, 240, 300 and 360 min, according to the infants' weights. Plasma paracetamol concentrations were measured by a Colorometric Assay, Ectachem Clinical Chemistry Slides (Johnson & Johnson Clinical Diagsnostics). RESULTS: The plasma paracetamol concentrations were mainly below the therapeutic (i.e. antipyretic) range of 66-132 micromol/l and did not exceed 160 micromol/l in any infant. The mean maximum plasma concentration (Cmax) was 72.4 micromol/l (+/-33.5 micromol/l) and the time to Cmax, i.e. the mean Tmax was 102.4 min (_+59.1 min). The mean "apparent" terminal half-life (n=10) was 243.6 min (+/-114.1 min). CONCLUSION: The absorption of rectal paracetamol (mean dose 23.9 mg/kg, +/-4.2mg/kg) in young infants <160 days is variable and often prolonged and achieves mainly subtherapeutic plasma concentrations.

Amethocaine gel for percutaneous local anaesthesia.

Amethocaine gel is a recently developed formulation of amethocaine, designed to provide percutaneous local anaesthesia. Its pharmacological characteristics coupled with a phase-change gel formulation may confer therapeutic advantages over existing preparations. Percutaneous local anaesthesia has increasing relevance in analgesia for paediatric procedures and superficial surgical operations.

Postoperative nausea and vomiting in paediatric surgical inpatients.

A prospective study of postoperative nausea and vomiting (PONV) was conducted in 415 children presenting for inpatient surgery. The overall incidence of PONV was 18.1%). The highest incidence was in children undergoing ENT procedures and increased with age. Avoidance of intraoperative opioids and the use of local anaesthesia and/or non-steroidal anti-inflammatory drugs reduced the incidence of nausea and vomiting postoperatively.

An evaluation of a new self-adhesive patch preparation of amethocaine for topical anaesthesia prior to venous cannulation in children.

A new preparation of amethocaine in the form of a self-adhesive patch, designed to provide topical cutaneous anaesthesia prior to venous cannulation, was evaluated in an open study of 189 children. The new preparation of amethocaine was in place for a mean time of 48 min (SD 3.9). Eighty percent of patients had a satisfactory degree of analgesia for venous cannulation. Nine percent of patients experienced moderate pain and 11% experienced severe pain during venous cannulation. In 26% of patients there was slight (24%) or moderate (2%) erythema at the site of application, and in 5% slight oedema was noted at the site of application. Eight percent of patients had slight itching and 1% had moderate itching at the site of application. There was a clinical impression that venous dilatation made cannulation easier than with EMLA cream. These results suggest that this convenient preparation of amethocaine is highly effective at providing adequate topical cutaneous anaesthesia with a short onset time and a low incidence of minor side effects with no evidence of systemic toxicity.

The minimum effective dose of lignocaine to prevent injection pain due to propofol in children.

In a single-blind study of 100 children aged 1 to 10 years, the minimum effective dose of lignocaine required to prevent injection pain due to propofol was 0.2 mg.kg-1 when veins on the dorsum of the hand were used. This is more than twice the adult value. We concluded that injection pain should not limit the use of propofol in children if an adequate amount of lignocaine is mixed immediately prior to injection.