Silicon-related syndrome in dialysis patients.

Two dialysis patients with markedly elevated plasma silicon (Si) levels (3,849 and 2,350 micrograms/l, respectively) and a presumed Si-related syndrome are described in this report. One patient presented with transient hypercalcemia in the face of low PTH, vitamin D and plasma A1 levels. Both patients had painful, nodular skin eruptions and aberrant hair growth, characterized as perforating folliculitis on skin biopsy, compatible with known effects of organosilicon compounds in man and animals. Plasma Si was found to be moderately elevated in 30 dialysis patients studied at random (710 +/- 53 micrograms/l, dialysis, vs. 152 +/- 9 micrograms/l, normal control), but there was no significant difference between the arterial values before and after dialysis, implying that the source of Si was ingested foods and fluids rather than dialysate. In these patients, plasma Si was weakly correlated with serum calcium as well as with serum calcium corrected for serum albumen, indicating that Si, like aluminum, may affect calcium metabolism.

Early absorption of enteral ranitidine after major laparotomy.

Thirty-six patients were studied following abdominal aortic surgery to determine if a commonly used medication could be absorbed from the gastrointestinal (GI) tract in the early postoperative period. Patients were randomized into two groups: Group I received ranitidine elixir 3 mg/kg via nasogastric tube every 12 hours; Group II received intravenous (IV) ranitidine 1 mg/kg every 8 hours. Ranitidine serum levels were measured with high performance liquid chromatography 1 hour after administration of the first three doses. Gastric pH was measured every 4 hours. It was found that serum ranitidine levels generally regarded as clinically effective were achieved in both groups. Although the levels were significantly higher following intravenous (IV) administration (Group II), there were no differences in average gastric pH. The authors conclude that within 24 hours of aortic surgery enterally administered ranitidine is effectively absorbed and provides prophylaxis equivalent to IV administration of the drug at lower cost. Other medications might be deliverable via the GI tract in the early postoperative period.

Isolation of drugs from blood serum by the Du Pont Prep I Automated Sample Processor and a C18 bonded phase adsorption column.

We describe a fast and efficient method for the isolation of drugs from blood serum by use of the DU PONT PREP I Automated Sample Processor and octadecyl bonded phase columns. Drugs are selectively adsorbed onto C18 bonded phase and eluted with methanol. The recovered residue is essentially free of sample matrix chromogens and shows very low background on thin layer chromatography. It is also suitable for analysis by gas liquid chromatography and high pressure liquid chromatography. Recovery of drugs added to serum is greater than 90 per cent for most drugs studied which include weakly acidic, neutral and alkaline drugs. The method offers tremendous savings to the user in time and dollars, since it is fully automated from the extraction step to the drying of the extract, and the columns are reusable at least 10 times. Up to 12 samples can be processed simultaneously in less than 60 minutes.