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Biomedical subjects

H G Boxenbaum

Publications and source records attributed to H G Boxenbaum.

13 recordsLinked to original sources
PubMed1978

Pharmacokinetics of flunitrazepam following single- and multiple-dose oral administration to healthy human subjects.

Healthy human subjects received single and multiple oral doses of flunitrazepam. Absorption and disposition were first order and reproducible from administration. The oral doses were virtually completely available to the liver, and elimination from the body occurred entirely via metabolism. Assuming the liver to be the sole eliminating organ, hepatic blood clearance and extraction ratio were approximately 0.235 liter/hr/kg and 0.154, respectively. Steady-state blood volume of distribution averaged 3.76 liters/kg in the single-dose studies. Terminal exponential half-lives from the single- and multiple-dose studies (different subjects) averaged 13.5 and 19.2 hr, respectively; these differences were not due to clearance changes but were entirely attributable to variations in volumes of distribution.

Administration, Oral↗
PubMed1977

Pharmacokinetics of sulphadimethoxine in cattle.

Four healthy Angus steers received a single rapid intravenous injection of sulphadimethoxine at a dose of approximately 55 mg/kg. The elimination half-life determined from plasma concentration-time data was approximately 12-5 h, and the volume of distribution was 31-0 per cent of body weight. Animals also received sulphadimethoxine intravenously or orally at a loading dose of approximately 55 mg/kg, followed by sustaining oral doses of approximately 27-5 mg/kg at 24, 48 and 72 h. It was demonstrated that oral maintenance doses served to sustain sulphonamide plasma concentrations achieved with the loading dose.

Administration, Oral↗
PubMed1977

Radioimmunoassay of atropine in plasma.

Antibodies, against atropine, were produced in rabbits immunized with atropine conjugated to bovine serum albumin. The antisera possessed a high binding affinity and were quite specific. The sensitivity of the method allowed detection of 6.25 ng of atropine per ml of plasma in a 10-microliter specimen. The method does not require an extraction procedure and can be performed using very small volumes of plasma. Plasma concentration-time profiles were determined by this method in dogs after rapid i.v. administration of atropine. Atropine declined from plasma in a biexponential fashion, exhibiting a terminal half-life of approximately 2.1 hours.

Animals↗
PubMed1976

Influence of route of administration on physiological availability of levodopa in dogs.

The physiological basis for the reduced levodopa bioavailability following oral administration was investigated. Four dogs received single 25-mg/kg doses of 14C-levodopa on three separate occasions in a crossover fashion via hepatoportal catheter, intravenous, and oral administrations. Plasma and urine specimens were analyzed for intact levodopa and total radioactivity. The ratios of areas under the plasma concentration-time curves following hepatoportal and intravenous adminstrations were close to unity, and the shapes of the curves were virtually identical. Following oral administration, however, significant reductions in the areas under the plasma concentration-time curves were observed. These data indicate that the physiologically impaired bioavailability of orally administered levodopa occurs almost exclusively as a result of metabolic degradation within the GI lumen and/or gut wall.

Administration, Oral↗