Biomedical subjects

R C Meatherall

Publications and source records attributed to R C Meatherall.

24 records · Page 2Linked to original sources

PubMed1983

Interference of selected second- and third-generation cephalosporins with creatinine determination.

The interference of selected second- and third-generation cephalosporins and cephalosporin-like antibiotics with serum and urine creatinine determinations was studied. Single determinations of apparent creatinine concentrations in serum, urine, and water samples were measured by three methods--manual, automated dialysis (SMAC 12/60), and direct kinetic (KDA Analyzer). Various concentrations of each cephalosporin were tested for interference with creatinine determinations. Drugs studied were cefoxitin, cefamandole, cefotaxime, ceftazidime, cefoperazone, ceftizoxime, moxalactam, ceftriaxone, and ceforanide. Cephalosporins demonstrating interference with one or more methods were further tested at concentrations representing the range of clinically achievable serum and urine drug concentrations. Cefoxitin, ceforanide, moxalactam, ceftizoxime, and ceftriaxone demonstrated significant interference in the screening tests. In subsequent testing, interference was shown at clinical concentrations of cefoxitin (all three methods) and ceforanide (manual and KDA methods). Where interference occurred, the degree varied with the assay method and the drug concentration. Recommendations are presented for serum and urine sampling for creatinine determinations in patients receiving cefoxitin and ceforanide. Based on the relationship between test interference and concentrations of these drugs achievable in patients with varying degrees of renal dysfunction, only cefoxitin and ceforanide can be expected to cause significant false elevations in vivo. To minimize interference, blood samples should be drawn at the time of minimum drug concentration.

Cephalosporins↗

PubMedDate not supplied

A sensitive thin-layer chromatographic procedure for the detection of urinary 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid.

A sensitive high-performance thin-layer chromatographic (HPTLC) procedure for the detection of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), the major urinary metabolite of delta 9-tetrahydrocannabinol (THC), is described. After alkaline hydrolysis, the THC-COOH is extracted from acidified urine into hexane. The hexane is evaporated and the residue spotted onto an HPTLC plate. Chromatography time is 11 min with heptane/butanol/acetic acid (90:9:1) as mobile phase. The cannabinoids are visualized by sequentially dipping the thin-layer plate in diethylamine then in 0.1% Fast Blue BB. The limit of detection for THC-COOH is 5 ng/mL when 2 mL of urine is used. Extraction efficiencies averaged 71% over the 10-400 ng/mL range. No drugs, drug metabolites, or endogenous urinary substances interfere with the procedure.

Chromatography, Thin Layer↗

PubMedDate not supplied

High urinary cannabinoids from a hashish body packer.

A body packer swallowed 39 condoms containing a total of 518 g hashish oil. He was arrested on entry into Canada. Two days later, a urine sample was obtained. Total cannabinoid concentrations by TDx and Emit II were 10,200 ng/mL and 11,400 ng/mL, respectively. The concentration of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid by gas chromatography/mass spectrometry was 1140 ng/mL.

Cannabinoids↗

PubMedDate not supplied

CEDIA dau Benzodiazepine screening assay: a reformulation.

The CEDIA dau Benzodiazepine assay has been reformulated to include online hydrolysis of urinary benzodiazepine glucuronide conjugates. The new antibody possesses enhanced cross-reactivities toward the low-dose benzodiazepines, which are excreted at low urinary drug-metabolite concentrations. The screening method was evaluated using lorazepam as the probe benzodiazepine. Four subjects each consumed a 1-mg lorazepam tablet. Sequential urine voids over the same time intervals were collected for the next 48 h. Twelve postdose urine samples were collected from each subject. Positive results were obtained from 5-24 h to 2-35 h using a 200-ng/mL nitrazepam calibration cutoff. There was no practical difference between hydrolyzing online with the supplied E. coli beta-glucuronidase or offline with Helix pomatia beta-glucuronidase purchased separately. Without hydrolysis, all urine samples tested negative. The cross-reactivities of lorazepam in terms of nitrazepam calibration equivalents, varied from 108 to 178% for lorazepam concentrations between 50 and 2500 ng/mL. Lorazepam glucuronide gave cross-reactivities (expressed as lorazepam base) between 72 and 136% using the online hydrolysis procedure with E. coli beta-glucuronidase. Offline hydrolysis with Helix pomatia gave cross-reactivities between 84 and 134%. Without hydrolysis, lorazepam glucuronide gave less than 4% cross-reactivity in the assay.

Anti-Anxiety Agents↗

PubMedDate not supplied

Diazoxide in the management of chlorpropamide overdose.

Three cases of chlorpropamide overdose are reported. Plasma levels of chlorpropamide, diazoxide, glucose, and insulin are presented for each patient during treatment. The simultaneous analysis of chlorpropamide, hydrochlorothiazide, and diazoxide in plasma by high pressure liquid chromatography (HPLC) is also reported. Although all three cases presented at hospital with potentially lethal plasma levels of chlorpropamide, each was successfully treated with intravenous diazoxide and glucose. Plasma diazoxide concentrations between 50-100 microgram/mL appear to be optimal in achieving therapeutic control of chlorpropamide induced hypoglycemia.

Adolescent↗

PubMedDate not supplied

A fatal overdose with clomipramine.

A death attributed to self administration of toxic amounts of clomipramine is reported. Analysis of post mortem blood showed clomipramine at a concentration of 540 ng/mL and its active metabolite, N-desmethylclomipramine, at a concentration of 580 ng/mL. The corresponding concentrations of the parent compound and metabolite in the urine were only 350 ng/mL and 700 ng/mL, respectively. These blood results are construed to represent minimum lethal concentrations for the two combined compounds.

Chromatography, Gas↗