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Biomedical subjects

R A Mactier

Publications and source records attributed to R A Mactier.

At least 37 records · Page 2Linked to original sources
PubMed1991

Aluminium content of water for injection used with recombinant human erythropoietin.

Human recombinant erythropoietin is of proven value in the treatment of the anaemia of renal failure. The aluminium content of 36 ampoules of water for injection supplied for use with recombinant erythropoietin has been measured and ranged from 24 to 450 micrograms/l, with a median of 251 micrograms/l. In three samples, which may have been contaminated on opening, the range was from 1770 to 6160 micrograms/l. In Water for Injection BP, values ranged from 66 to 140 micrograms/l with a median of 99 micrograms/l. Reconstituted erythropoietin did not contain any more aluminium than could be accounted for by the water. Ampoules of a second brand of erythropoietin, supplied already in solution, contained from 506 to 837 micrograms/l aluminium (median 682 micrograms/l). In view of the lifelong duration of erythropoietin therapy clinicians and pharmaceutical companies should be aware of this potential problem. Although the amount of aluminium delivered with each injection is usually less than 4 micrograms, it is suggested that active steps are taken to establish a British Pharmacopoeia limit on the aluminium content of injections.

Aluminum↗
PubMed1991

Aluminum and deferoxamine kinetics in CAPD.

Reduced renal clearance of aluminum and regular intake of aluminum containing phosphate binders render dialysis patients at increased risk of aluminum accumulation and toxicity. Provided the inflow dialysate aluminum concentration is kept low (less than 10 micrograms/L) most CAPD patients have negative peritoneal mass transfer of aluminum in the effluent dialysate. Net removal of aluminum in the dialysate partially compensates for the loss of renal clearance of aluminum and helps prevent progressive tissue accumulation of aluminum. Rates of aluminum removal in the dialysate are too low, however, for effective treatment of patients with established aluminum accumulation or overt aluminum toxicity. Such patients usually require parenteral deferoxamine therapy to achieve increased aluminum removal rates. The optimum route, dosage and frequency of administration of deferoxamine in CAPD patients are not established. From the existing data, 2 g deferoxamine administration intraperitoneally three times per week in the overnight exchange appears to provide the maximum aluminum removal for minimum deferoxamine dosage.

Aluminum↗
PubMed1991

Investigation and management of ultrafiltration failure in CAPD.

Apparent loss of peritoneal ultrafiltration capacity may occur when fluid intake is excessive, residual urine volumes decrease or the patient does not perform exchanges regularly and should be suspected if drain volumes are unchanged. True loss of ultrafiltration capacity (reduced drain volumes) is potentially reversible if due to catheter malposition, internal dialysate leakage or recent peritonitis but is usually permanent if kinetic studies indicate a sustained reduction in net transcapillary ultrafiltration or increased lymphatic drainage. Three types of irreversible ultrafiltration failure have been identified of which high peritoneal solute transport rates resulting in rapid dialysate glucose absorption (Type 1 membrane failure) is the most common. Transcapillary ultrafiltration may also be reduced due to very low peritoneal solute transport rates (Type 2 membrane failure) in patients with sclerosing peritonitis or massive peritoneal adhesions but is now rare. Ultrafiltration failure due to high lymphatic drainage (Type 3 failure) is also uncommon. Treatment strategies in patients with Type 1 failure include achieving the maximum urine output with diuretics, reducing fluid intake to the minimum tolerated by the patient, changing to short dwell exchanges (daytime ambulatory peritoneal dialysis (DAPD) or machine peritoneal dialysis overnight) and temporary hemodialysis which may lead to a spontaneous reduction in peritoneal transport rates in some patients. Patients with Type 2 and Type 3 failure require permanent transfer to hemodialysis.

Biological Transport↗
PubMed1990

Effect of peritonitis on insulin and glucose absorption during peritoneal dialysis in diabetic rats.

The intraperitoneal route is frequently used for the administration of insulin in diabetic continuous ambulatory peritoneal dialysis patients. However, there is conflicting evidence as to whether the dosage of intraperitoneal insulin should be increased or decreased during peritonitis in these patients. Glucose and insulin absorption and glycaemic control were evaluated in 2-hour exchanges using 15 ml of 2.5% dextrose dialysis solution in diabetic rats with (group 1) and without (group 2) peritonitis. Fasting blood glucose values at the beginning of the study exchanges were mean +/- SD 17.9 +/- 3.3 mmol/l in group 1 and 18.2 +/- 3.5 mmol/l in group 2. Even though group 1 had a higher percentage absorption of dialysate glucose (65 +/- 19 vs. 47 +/- 7%; p less than 0.05) and higher percentage absorption of dialysate insulin (49 +/- 12 vs. 44 +/- 14%; p less than 0.1), the hypoglycaemic response to the standard intraperitoneal dose of insulin was similar in each group. Plasma C peptide levels remained very low in both groups, thus excluding significant endogenous release of insulin. These data indicate that peritonitis per se does not change intraperitoneal insulin requirements during standardized peritoneal dialysis exchanges in diabetic rats. Insulin requirements may also be unaltered during peritonitis in diabetic continuous ambulatory peritoneal dialysis patients, provided that dialysate glucose load and oral carbohydrate intake are kept constant.

Absorption↗
PubMed1990

Calcium carbonate 1250 mg/1260 mg: an effective phosphate binder.

Calcium carbonate is currently the first choice phosphate binder in renal failure. In the UK its most widely prescribed formulation is a combination of calcium carbonate 420 mg and glycine 180 mg (Titralac 3M Riker). In order to achieve adequate reduction in the serum phosphate level, up to 12 of these tablets may be required daily. In a group of seven patients, we have compared Titralac with two alternative preparations containing calcium carbonate 1250 mg (Calcium-500 Macarthy's Medical Ltd) and calcium carbonate 1260 mg (Calcichew Shire Pharmaceuticals Ltd). Given at a third of the daily number of Titralac tablets, both these newer preparations were effective phosphate binders and produced no statistically significant change in serum calcium and phosphate. The important advantage of such a reduced tablet load is improved patient compliance with phosphate binder therapy. Calcium-500 is also a cost-effective treatment slightly reducing the cost when compared with combined calcium carbonate 420 mg and glycine 180 mg.

Adult↗
PubMed1988

Kinetics of peritoneal dialysis in children: role of lymphatics.

Intraperitoneal fluid is absorbed continuously by convective flow into the peritoneal cavity lymphatics. We evaluated the role of lymphatic absorption in the kinetics of peritoneal dialysis during standardized four hour exchanges in six children using 40 ml/kg of 2.5% dextrose dialysis solution. Cumulative lymphatic absorption averaged 10.4 +/- 1.6 ml/kg and reduced the total net transcapillary ultrafiltration during the dwell time by 73 +/- 10%. Due to the considerable lymphatic absorption rate, maximum intraperitoneal volume was observed before osmolar equilibrium. Extrapolated to four study exchanges per day, lymphatic absorption decreased the potential daily drain volumes in the children by 27 +/- 5% and daily peritoneal urea and creatinine clearances by 24 +/- 4% and 22 +/- 5%, respectively. Compared with four hour exchanges using two liters of 2.5% dextrose dialysis solution in 10 adult CAPD patients with average peritoneal transport, the children had more rapid equilibration of urea, greater absorption of dialysate glucose, higher lymphatic absorption and lower net ultrafiltration (P less than 0.01 to P less than 0.05). Lymphatic absorption therefore causes a relatively greater reduction in net ultrafiltration and solute clearances in children than in adults.

Adolescent↗
PubMed1988

Hyperkalemia induced by indomethacin and naproxen and reversed by fludrocortisone.

We have described a patient with severe rheumatoid arthritis and a history of mefenamic acid nephropathy in whom hyperkalemia and inappropriate hypoaldosteronism were caused by both indomethacin and naproxen, without major decline in renal function. It is likely that preexisting renal disease predisposed this patient to type IV renal tubular acidosis with prostaglandin synthetase inhibitors. Because he was unable to discontinue nonsteroidal anti-inflammatory drug therapy, fludrocortisone was added, correcting the hyperkalemia and allowing indomethacin therapy to be continued safely.

Fludrocortisone↗
PubMed1988

Diabetic glomerulosclerosis without concurrent diabetes mellitus.

In four adults with idiopathic nephrotic syndrome and azotemia, percutaneous renal biopsy showed diabetic glomerulosclerosis, yet none had oral glucose tolerance tests diagnostic of diabetes mellitus or funduscopic evidence of diabetic retinopathy. Possible concomitant glomerular disease that may have produced proteinuria was excluded. Well documented cases of diabetic glomerulosclerosis without concurrent glucose intolerance are uncommon, and almost 30% of such patients have a past history of diabetes. Despite the absence of overt diabetes at onset of diabetic glomerulosclerosis, these patients warrant careful monitoring of plasma glucose levels and strict control of systemic hypertension.

Aged↗
PubMed1988

Pharmacological reduction of lymphatic absorption from the peritoneal cavity increases net ultrafiltration and solute clearances in peritoneal dialysis.

Lymphatic drainage from the peritoneal cavity occurs mainly via the subdiaphragmatic stomata and significantly reduces net ultrafiltration and solute clearances during long-dwell peritoneal dialysis. Intraperitoneal cholinergic drugs constrict these stomata and may reduce peritoneal cavity lymphatic absorption. We evaluated ultrafiltration kinetics, solute transport, and lymphatic drainage during single hypertonic exchanges in rats using 2.5% dextrose dialysis solution with and without added neostigmine. Net ultrafiltration was enhanced in the neostigmine group (p less than 0.01) by a reduction in cumulative lymphatic absorption (p less than 0.01) and without an increase in total transcapillary ultrafiltration during the dwell time. Likewise solute clearances were significantly augmented with neostigmine primarily due to the increase in dialysate drain volume (p less than 0.01) since dialysate/serum solute ratios were unchanged. Pharmacological manipulation of peritoneal lymphatic absorption provides an alternative means of increasing the efficiency of long-dwell peritoneal dialysis without altering peritoneal transport of solutes and water.

Absorption↗
PubMed1987

Ultrafiltration failure in continuous ambulatory peritoneal dialysis due to excessive peritoneal cavity lymphatic absorption.

We describe a continuous ambulatory peritoneal dialysis (CAPD) patient who developed failure of ultrafiltration for no apparent cause during the first year of treatment. Further investigation showed that peritoneal cavity lymphatic reabsorption during the dwell time exceeded cumulative transcapillary ultrafiltration and so caused negative net ultrafiltration. Peritoneal lymphatic drainage should be added to the list of causes that, either singly or in combination, lead to loss of ultrafiltration in CAPD.

Absorption↗