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1 Prednisolone binding in human serum and to recrystallized human serum albumin was measured by continuous ultrafiltration. 2 At serum concentrations of prednisolone up to 0.6 micron, 95.0% was bound but at higher concentrations the binding became non‐linear falling to 80.5% at 1.8 microns. At even higher concentrations binding in serum became linear again and paralleled the binding to albumin which was linear throughout the entire range of prednisolone concentrations. 3 A binding model was proposed which included a saturable component attributable to binding to transcortin and a non‐saturable binding to albumin. 4 Computer simulations using the experimentally determined binding parameters of the model indicated that binding in serum was critically dependent on transcortin concentration and almost independent of albumin concentration.

1 The concentration of oxytetracycline in plasma was studied by microbiological assay after oral administration of five different preparations of the antibiotic. None of these preparations had been studied previously. 2 There was a statistically significant correlation between the time required for 50% dissolution at pH 2 and biological availability, as assessed by the peak plasma level or the area under the plasma concentration‐time curve. 3 The mean bioavailability of oxytetracycline was greatest with preparations of the hydrochloride, and with film‐coated tablets of the dihydrate. In contrast, sugar‐ coated tablets of oxytetracycline dihydrate were associated with poorer dissolution characteristics and reduced biological availability.

The effect of syrup, B.P. and codeine phosphate syrup, B.P.C. on blood alcohol levels was determined in six normal subjects. 2 Treatment with syrup alone had little or no influence on the concentration of ethanol in blood. 3 In contrast, pretreatment with codeine phosphate syrup significantly reduced alcohol absorption, as assessed by the maximum blood levels achieved or the area subtended by the blood concentration‐ time curve. It is suggested that the diminished absorption of ethanol is related to the pharmacological action of codeine on the stomach. 4 It was considered that the concentration of ethanol in linctuses or syrups containing codeine was unlikely to have any significant effect on the central nervous system.

1 Chronic propranolol treatment has been previously shown to lower the plasma concentrations of LH and prolactin in normal male volunteers. 2 The effect of 2 weeks treatment with propranolol (80 mg twice daily) on the plasma concentrations of LH and prolactin has now been investigated in five post menopausal hypertensive women. 3 There was no significant effect of propranolol treatment on the basal plasma concentrations of either hormone. Both hormones showed significant increases in plasma concentration following GnRH stimulation and these increases were also unaffected by propranolol treatment.

The protein binding of vinblastine was measured in the serum from 6 normal subjects and 9 patients with Hodgkin's disease. Cellulose acetate electrophoresis showed that the predominant binding protein fractions were the alpha 1- and alpha 2-globulins with little binding to albumin and beta- and gamma-globulins. At a serum concentration of 10 nM a significantly lower percentage bound was found in the patient group (p = 0.001). Binding to both groups was very high at 99.7% bound in the normal subjects and 98.9% bound in the patient group. Binding in both groups was best described by a two class protein binding model with higher and lower affinity binding sites. No significant difference was found on inter-group comparisons of binding parameter values.

1 Gentamicin alone (dose 1 mg/kg) or in combination with frusemide (dose 0.25 mg/kg) or piretanide (dose 0.1 mg/kg) was administered intravenously to six healthy male volunteers. 2 Blood samples were collected at various times for 24 h and urine for up to 48 h. 3 Both diuretics increased the renal clearance of gentamicin during the period of the diuresis, without influencing either the glomerular filtration rate or the distribution of the antibiotic. 4 The results are discussed in relation to gentamicin-induced nephrotoxicity.