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Biomedical subjects

B S Hebron

Publications and source records attributed to B S Hebron.

11 recordsLinked to original sources
PubMed1994

Stability of caffeine oral formulations for neonatal use.

The stability of an oral formulation of 10 mg/ml caffeine citrate (equivalent to 5.03 mg/ml caffeine free base), which was preserved with potassium sorbate, was assessed at a range of temperatures. There was no appreciable change in pH or caffeine content over 1 year, even at storage temperatures of 32 degrees C and 45 degrees C. A batch-to-batch difference in the stability of potassium sorbate was detected, with losses over 1 year of 2% and 11% for two batches at 25 degrees C and 10% and 30%, respectively, at 45 degrees C. The formulation complied with the Antimicrobial Preservative Efficacy test of the British Pharmacopoeia throughout a period of storage at 25 degrees C for 1 year. There was no detectable benefit to preservative efficacy by adding 20% w/v sorbitol as an osmotic agent. The formula with no sorbitol may be preferable due to the potential for sorbitol to cause gastrointestinal upset. A shelf-life of 1 year at room temperature is feasible. The additional precaution of limiting the in-use storage life to 1 month after opening is recommended to ensure acceptable microbiological quality.

Administration, Oral↗
PubMed1984

Intravenous sedation for the intubated and spontaneously breathing patient in the intensive care unit.

A technique is described for the management of post-operative patients who have undergone major craniofacial surgery. Under supervision on the Intensive Care Unit, the patients breathe humidified, oxygen-enriched air through a naso-tracheal tube. Sedation and analgesia are provided by continuous infusions of etomidate (variable rate) and fentanyl (fixed rate), administered by volumetric infusion pumps (IMED 922). Six patients have been studied in detail and our results are presented. In conjunction with fentanyl, a mean infusion rate of 3.72 micrograms . kg-1 . min-1 of etomidate provided good sedation and analgesia, without clinically significant respiratory depression. The patients found the technique very acceptable and no side-effects were noted.

Carbon Dioxide↗
PubMed1983

Pharmacokinetics of etomidate associated with prolonged i.v. infusion.

Plasma concentrations of etomidate have been measured in six patients who required intermittent positive pressure ventilation following surgery. There was an approximately linear relationship between the plasma concentration and the rate of infusion of etomidate. The drug exhibited linear pharmacokinetics over a 10-fold variation in plasma concentration. The decrease in the plasma concentration after discontinuing the infusion was consistent with a three-compartment pharmacokinetic model. The plasma terminal half-life was found to be about 5.5 h, and the clearance calculated to be 0.025 litre kg-1 min-1.

Adolescent↗
PubMed1983

Plasma concentrations of etomidate during an intravenous infusion over 48 hours.

Two groups of six patients who had undergone major maxillofacial surgery and who required intermittent positive pressure ventilation, analgesia and sedation for about 48 hours postoperatively were studied. Analgesia in the postoperative period was maintained by an infusion of fentanyl 0.034 micrograms/kg/minute. Sedation was maintained with an intravenous infusion of etomidate such that the patients slept but opened their eyes when addressed and obeyed commands. An assay method was developed which enabled the measurement of plasma concentration of etomidate for periods of up to 24 hours after stopping the infusion. The steady state plasma concentration associated with the technique which produced the required degree of sedation was found to be 158 micrograms/litre (SEM 36). Etomidate exhibited linear pharmacokinetics and the decrease in plasma concentration of etomidate after stopping the infusion was consistent with a three-compartment pharmacokinetic model. All the patients recovered within 1 hour of stopping the infusion. The use of results obtained from the first group of six patients enabled a dosage regimen to be calculated that used a two stage infusion. This regimen enabled a reduction in the time taken to establish the appropriate degree of sedation in the second group of six patients. The two-stage infusion technique provides a means of rapid sedation and of maintaining a suitable clinical response for the prolonged periods that may be necessary when patients are transferred to an intensive therapy unit.

Anesthesia, Intravenous↗
PubMed1982

Safer sedation for ventilated patients. A new application for etomidate.

A technique is described for sedation of ventilated patients. Six patients who underwent major maxillofacial surgery were given low dose infusions of etomidate and fentanyl for postoperative sedation. Measurements of respiratory function were recorded before and during the period of intermittent positive pressure ventilation. Plasma etomidate levels were estimated. After initial stabilisation on almost constant rate of infusion was used to provide a reproducible level of sedation from which the patients were easily aroused. All patients maintained an adequate minute volume when disconnected from the ventilator. All measured and derived respiratory indices remained within normal limits. Patients exhibited amnesia throughout the period of infusion. All patients found this method of sedation pleasant. This technique may be recommended as an alternative to conventional methods of sedation for ventilated patients.

Adolescent↗
PubMedDate not supplied

Folic acid and total parenteral nutrition.

The stability of folic acid in a variety of solutions used for parenteral nutrition has been determined over a 2-wk period. Provided that the acidity of the solution remains above pH 5.0 the folate, in the concentrations usually used for parenteral nutrition, will remain stable in solution, and all of the folate added to the solution will be delivered to the patient. The applicability of this in vitro work to a group of patients requiring parenteral nutrition was assessed, in order to determine a suitable dose. A dose of 0.2 mg of folic acid daily was inadequate to meet the requirements of these patients. In contrast a dose of 1.2 mg daily for 7 days was sufficient to cause an increase in the serum folate concentration.

Dose-Response Relationship, Drug↗
PubMedDate not supplied

A microcomputer system for the identification of drug interactions.

The condition of critically ill patients may change rapidly. The consequent alterations in drug therapy may result from the advice of a number of specialists, some of whom may not be skilled in the problems of adverse drug interactions. As a result, screening for drug contra-indications by someone with the necessary experience often occurs after the patient has already received the drug. By providing information on drug interactions on an inexpensive microcomputer, the necessary screening for adverse interactions can take place before the administration of the drug. A software package, written in FORTRAN, which can handle the storage and retrieval of this type of information, is described. The system can assess up to 18 drugs simultaneously, from a data-base comprising the 102 stock drugs held by the Intensive Therapy Unit at Rotherham District General Hospital, together with 25 other drugs, which could interact with the stock drugs to produce serious or possibly fatal consequences. It also differentiates between therapeutic interactions and chemical or physical incompatibilities.

Computers↗