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Biomedical subjects

F E Crawley

Publications and source records attributed to F E Crawley.

12 recordsLinked to original sources
PubMed1983

The retention of 14C-DTPA in human volunteers after inhalation or intravenous injection.

This study in human volunteers was designed to compare the retention of diethylenetriaminepentaacetic acid (DTPA) in the body after intravenous (i.v.) injection with that following inhalation by using a 14C labelled tracer. After i.v. injection retention in the blood could be described by three exponential components with half-times of about 1.4 min (approximately 60%) 14.3 min (approximately 20%) and 95 min (approximately 20%). By 24 hr more than 99% of the 14C-DTPA had been excreted in the urine and less than 0.5% remained in the plasma. After inhalation of 14C-DTPA retention in the lungs could be represented by a single component with a half time of about 75 min. As a consequence the length of time that a therapeutically useful amount of DTPA is retained in the body is approximately twice that following intravenous injection.

Adult↗
PubMedDate not supplied

Bioavailability of 125I bromelain after oral administration to rats.

Bromelain is a sulphydral protease, derived from the stem and fruit of pineapples. Semi-purified preparations of bromelain are used in the treatment of inflammation and oedema. There is however no unequivocal proof of the absorption of the enzyme after oral administration. In this study, 125I-bromelain was administered orally to rats and blood sampled at various times. The total radioactivity, the TCA precipitable 125I-compounds and the molecular weight profile of 125I-proteins in the plasma were determined. A maximum level, equivalent to 270 ng ml-1 bromelain was found at 1 h after administration. Approximately 40 per cent of the 125I in plasma could be precipitated by 10 per cent trichloroacetic acid. Electrophoretic analysis showed one major peak of radioactivity in the plasma samples, with a molecular weight of 26-32,000 daltons. This is identical to the main molecular weight fraction in the Bromelain mixture and corresponds to the molecular weight of the purified enzyme. In the 1 h plasma sample this peak contained 0.003 per cent of the administered dose per millilitre.

Administration, Oral↗
PubMedDate not supplied

Pharmacokinetics, metabolism and elimination of itanoxone in humans.

The pharmacokinetics, metabolism and elimination of Itanoxone was studied after a single oral administration of the carbon-14-labelled drug (500 mg) in four male volunteers. The drug was absorbed fairly rapidly with a mean peak plasma level of 10.3 +/- 1.3 micrograms/ml between 3 and 4 hours after dosing. The pharmacokinetics can be described by a two-compartment open model with the central compartment consisting of the extracellular fluid. The mean elimination half-life was 19.4 +/- 8.5 hours. Two metabolites as well as unchanged Itanoxone were detected in plasma. Approximately 37% of the radioactivity was excreted over a five-day period in the urine and 50% in the faeces. There were only traces of free metabolites in the urine as the rest of the radioactive metabolites were associated with glucuronide conjugates. These conjugates consisted of Itanoxone and up to six metabolites. Five of these metabolites have been tentatively identified by comparison of their chromatographic properties by TLC and HPLC with a number of reference compounds. After repeated administration of Itanoxone (250 mg b.i.d.) the maximum level at steady state was about 7 micrograms/ml and the minimum level, 0.6 micrograms/ml. The mean area under the plasma level time curve was 35% higher than in the single dose study after correction for dose.

Adult↗