1. Plasma pethidine levels have been monitored after the administration of 1.5 mg/kg intramuscularly to a group of young (under 30) and old (over 70) subjects. 2. Plasma levels were consistently higher in the old group, this was most marked for the first three hours but for most of the study there was a more than two-fold difference. 3. Differences in uptake from muscle and in metabolism were small and appeared unimportant. 4. Less pethidine was excreted in the elderly and this contributed to the overall differences in serum levels but was not important in explaining the marked disparity noted over the first three hours. 5. Red cell binding of pethidine by the young was much greater than by the old and if the differences in drug binding also applies to other tissues this would explain the high serum levels in the old and the increased incidence of side effects.

Adult↗

PubMed1975

Factors influencing the excretion and relative physiological availability of pethidine in man.

Factors influencing the urinary excretion of pethidine, norpethidine and pethidine N-oxide have been examined. The proportion of a dose of pethidine excreted unchanged or as norpethidine depends on the urinary pH and the route of administration. Older people appear to metabolize more of the drug and therefore excrete less unchanged pethidine. The rate of excretion of pethidine in acid urine is directly proportional to the plasma pethidine concentration and under these conditions the relative physiological availability of pethidine has been determined. It has not been possible to explain variations in the amount of pethidine excreted as the N-oxide.

Administration, Oral↗

PubMed1972

Binding of bromosulphthalein sodium by human serum albumin using a continuous diafiltration technique.

1. The recently introduced ultrafiltration-cum-dialysis technique termed continuous diafiltration has been used to obtain detailed binding isotherms of equilibrium solution concentration of bromosulphthalein (BSP) versus the number of molecules of BSP bound per molecule of human serum albumin for pure human serum albumin solutions (albumin concentrations: 1.59-3.39 g/100 ml) and for three dilutions of pooled human serum (albumin concentrations: 1.45-2.85 g/100 ml) in 310 ideal milliosmolar phosphate buffer at pH 7.4 and 22 degrees C.2. Qualitative analysis of the isotherms seems to indicate that there is a competition between the polymerization of the albumin to dimers and high oligomers and the binding of BSP by albumin.3. The binding capacity of pure human serum albumin at total BSP (bound and free) concentrations below 2.3 mM is greater than that of the pooled serum at an equivalent albumin concentration, possibly indicating the blockage of binding sites by more strongly binding ligands.4. The binding capacity of pure albumin at total BSP concentrations greater than 2.3 mM is less than that of pooled serum at an equivalent albumin concentration, suggesting the presence of other non-ultrafilterable materials in the serum capable of binding BSP.

Dialysis↗

PubMed1969

The criteria for friendship.

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Adolescent↗