Pharmacokinetics of teicoplanin in subjects with varying degrees of renal function.

The pharmacokinetics of teicoplanin were studied in 20 subjects with varying degrees of renal function after administration of a single 200 mg intravenous dose. Pharmacokinetic parameters were calculated with a three compartment open model and by non-compartmental analysis. The elimination half-life increased as creatinine clearance decreased (rs = -0.87, P less than 0.001). The distribution volume was 1.0 (+/- 0.3) 1/kg of actual body weight and did not vary with changes in creatinine clearance. In normal subjects the main route of elimination was renal. The plasma clearance of teicoplanin correlated with creatinine clearance (rs = 0.91, P less than 0.001). At lower levels of creatinine clearance the variation in elimination half-life was such that we recommend individualization of the teicoplanin dosage following the measurement of the drug concentration in plasma.

An electrophysiological study of ganglion blockade by paraquat and diquat.

1. The bipyridilium herbicides, particularly paraquat, have chemical and toxicological features in common with the bi-quaternary ammonium ganglion blockers. 2. Paraquat and diquat were tested for ganglion blocking activity. Rabbit cervical ganglia were superfused with both agents and subsequently with hexamethonium to confirm susceptibility to ganglion blockade. 3. No evidence for ganglion blockade was found at either supra maximal or sub maximal stimulation, and none following repetitive stimulation. 4. The similarities and differences between the bipyridyl herbicides and bi-quaternary ganglion blockers can be explained on the basis of their structures. 5. It is concluded that neither paraquat nor diquat have significant ganglion blocking activity.

Paraquat lung: is there a role for radiotherapy?

We have previously reported the clinical course of a patient poisoned with paraquat who was treated with whole lung irradiation and who survived severe pulmonary damage. Four further cases are reported who were much more severely poisoned and who died despite early pulmonary irradiation. There is no definite evidence that this or any other form of cytotoxic therapy can influence the course of paraquat lung. As there is no adequate laboratory model, further investigation of such therapy should be in the context of a prospective clinical trial. Treatment of only one lung would allow rapid identification of a therapeutic effect of irradiation.

Polycythaemia following renal transplantation: an association with azathioprine dosage?

Patients from a renal transplantation unit with an unusually high incidence of polycythaemia were divided into polycythaemic and control groups. The rate of rise of haemoglobin concentration was not significantly different in the two groups. The polycythaemic group received a significantly lower dose of azathioprine (p less than 0.005) and included more patients with polycystic disease than the control group (p less than 0.05). An effect of azathioprine on bone marrow function was suggested by the polycythaemic group also having a higher mean white cell count (p less than 0.02). Azathioprine dosage correlated negatively with post-transplantation polycythaemia regardless of the original cause of renal failure.

Pharmacokinetics of ciprofloxacin in healthy volunteers and patients with impaired kidney function.

The pharmacokinetics of ciprofloxacin were studied, in six healthy controls and in 18 patients with varying degrees of renal impairment, after administration of a single 100 mg intravenous dose. Pharmacokinetic parameters were calculated on a two compartment open model. The mean distribution volume was 2.1 (+/- 0.6) l/kg of ideal body weight; it did not correlate significantly with renal function. In the healthy volunteers 57 (+/- 9)% of the drug was eliminated by the kidney and 43% by other pathways. The renal clearance of ciprofloxacin correlated with creatinine clearance (rs = 0.93, P less than 0.001), and urinary excretion of the drug was markedly reduced in patients with the most severe degrees of renal impairment. Plasma clearance correlated with creatinine clearance (rs = 0.50, P less than 0.02). This together with the lack of correlation between non-renal clearance and renal function enables us to suggest an intravenous dosage schedule for patients with renal impairment.

A comparison of the uptake of human and porcine insulins given intraperitoneally to patients with diabetes mellitus on continuous ambulatory peritoneal dialysis.

Intraperitoneal absorption of human insulin (crb) and porcine insulin was examined in 9 diabetic patients with renal failure, and on Continuous Ambulatory Peritoneal Dialysis (CAPD). Serial blood sampling was performed to determine the characteristics of insulin absorption and glycaemic control. Four patients received successive equal doses of human and porcine insulins, 2 received different doses and 3 received human insulin only. Glycaemic control was similar after both insulins. Mean insulin levels were consistently higher after human insulin with significant differences at 90, 300 and 360 min. It is concluded that, if required, patients may be transferred from i.p. purified porcine to i.p. human insulin without a change in insulin dose.

Evidence against a role for superoxide ions in the injury of nephrotoxic nephritis in rats.

The accelerated model of nephrotoxic serum nephritis (NTSN) was produced in 12 Sprague-Dawley rats. Six of these rats were administered superoxide dismutase (EC 1.15.1.1; SOD) subcutaneously (8 mg/kg) 8-hourly for 4 days. The first dose was given 6 h before the nephrotoxic serum (NTS). The progression of renal disease was monitored by following (i) albumin excretion, (ii) serum creatinine and creatinine clearance and (iii) renal histopathology and immunofluorescence. There was no evidence that SOD influences the course of NTSN. SOD was scarcely excreted by control rats or rats with NTSN.

Pharmacokinetics of norfloxacin (MK 366) in patients with impaired kidney function--some preliminary results.

The concentration of norfloxacin in serum and urine was measured in five healthy volunteers and eleven patients with renal impairment following a 400 mg oral dose of norfloxacin. In impaired renal function the elimination rate of norfloxacin is decreased considerably whereupon the area under the curve (AUC) rises rapidly. The urinary concentration of norfloxacin decreases with renal function but therapeutic levels are still obtained for sensitive organisms. Patients with a glomerular filtration rate of less than 30 ml/min require dosage reduction and we would recommend a reduction to half the usual dosage.

Resolution after radiotherapy of severe pulmonary damage due to paraquat poisoning.

A 29 year old man was admitted 36 hours after ingesting about 5 g paraquat. His arterial oxygen pressure fell progressively to 3.4 kPa (34 mm Hg), and pulmonary damage induced by paraquat was diagnosed. His condition did not improve after treatment with prednisolone and cyclophosphamide, but after irradiation both lungs cleared and arterial oxygen pressure started to improve. Irradiation of the lungs should be considered in patients who, after surviving the acute phase of poisoning with paraquat, show progressive deterioration of respiratory function.

Nephrotoxicity of paraquat in the sheep and the associated reduction in paraquat secretion.

Paraquat was administered to sheep at doses of 1, 2, 4, and 8 mg/kg. Paraquat was nephrotoxic to sheep, producing glomerular and tubular defects. Glomerular filtration rate (GFR) fell in a dose-dependent manner. Secretion of paraquat into the tubule was inhibited at low doses prior to any influence of paraquat on GFR. Subsequently, GFR and paraquat clearance (ClPQ) fell in parallel. Inhibition of paraquat secretion by paraquat itself was dose dependent. Poisoning of the secretory component removed a large part of the excretory capacity for paraquat.

The pathophysiology of paraquat nephrotoxicity in the sheep.

The effect of intravenous paraquat on ovine renal function was examined at four dose schedules. Paraquat caused dose dependent reduction in ovine glomerular and tubular function, but glomerular filtration rate increased at a low dose. The earliest reduction in function involved the major energy dependent processes of the kidney to inhibit sodium reabsorption. There were marked shifts in fluid balance to which the kidney initially responded. As nephrotoxicity progressed the homeostatic response failed. Paraquat which is a quaternary amine may mimic the pharmacological behaviour of similar compounds which are ganglion blocking agents. Paraquat causes hyperglycaemia in sheep.