Propofol inhibits enzymatic degradation of alfentanil and sufentanil by isolated liver microsomes in vitro.

We have studied the effect of propofol on the enzymatic degradation of alfentanil and sufentanil utilizing isolated liver microsomes obtained from pig and human liver. Propofol inhibited dose-dependently the oxidative metabolic degradation of alfentanil and sufentanil by both microsomal preparations. The calculated concentration of propofol causing 50% inhibition of metabolic degradation (IC50) was 32.6 mumol litre-1 for alfentanil and 22.1 mumol litre-1 for sufentanil in pig liver microsomes. Similar values of inhibitory activity of propofol (IC50 values 62.8 and 52.9 mumol litre-1, respectively) were observed using human microsomes prepared from liver taken from an organ transplant donor. We suggest that propofol in clinically relevant concentrations interferes with oxidative metabolic degradation of alfentanil and sufentanil in the microsomal fraction of pig and human liver.

The route of prolonged morphine administration affects the pattern of its metabolites in the urine of chronically treated patients.

Differences in the patterns of urinary morphine metabolites were determined in 15 patients after the prolonged administration of morphine via various routes (oral, subcutaneous, intravenous). The possible correlation between metabolite pattern and the route of prolonged morphine administration was investigated. It was established that the concentration ratios of the active metabolite, morphine-6-glucuronide to morphine and its inactive metabolite, morphine-3-glucuronide are significantly (p less than 0.05) higher after prolonged oral morphine treatment than after the systemic administration (subcutaneous or intravenous infusion) of morphine. It may therefore be concluded that patients receiving morphine orally produced significantly greater amounts of its pharmacologically more active metabolite than patients subjected to chronic systemic morphine treatment.

Assessment and management of chronic pain.

The approach to the management of patients with a variety of chronic pain problems who present to the multidisciplinary Grey's Hospital Pain Clinic is outlined.

Self-administered intravenous analgesia during labour. A comparison between pentazocine and pethidine.

Pentazocine or pethidine was administered to healthy parturients up to the time of delivery using a self-demand (self-administration on demand) intravenous apparatus, the Cardiff Palliator. Good analgesia was obtained with both drugs. The patients receiving pethidine exhibited side-effects (nausea, vomiting and drowsiness), whereas there were no side-effects among those receiving pentazocine. Apgar and neurobehavioural scores of the babies of mothers in both groups were the same and did not differ from those of a third group of babies, the mothers of whom had received 4-hourly intramuscular pethidine on demand according to the usual hospital routine. The self-administration technique proved a safe and effective means of providing analgesia during labour and delivery, with pentazocine having a decided advantage over pethidine because of its lack of side-effects.

Chronic pain problems. Experience in a pain clinic.

Our experiences during a year of activity in a pain clinic are presented. Most of the patients treated had pain due to malignant disease. The assessment and management of these patients are described together with the treatment given and the result.