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H W Diekmann

Publications and source records attributed to H W Diekmann.

8 recordsLinked to original sources
PubMed1979

[Thin layer and high pressure liquid chromatography investigations with cefaclor in urine and serum (author's transl)].

After oral administration of 500 mg cefaclor, antibacterially active metabolites could not be detected in human urine using thin layer chromatography followed by bioautography. Degradation products of cefaclor could also not be detected in the serum of human volunteers (n = 10) using high pressure liquid chromatography with a reversed phase system. Cefaclor was eluated as a single and homogenous peak with a retention period of 2.9 min. High pressure liquid chromatography for the measurement of cefaclor serum levels and a technique for preparation of serum samples are described. After administration of 500 mg cefaclor to volunteers (n = 10), the average peak serum concentration of 9.8 mg/l, determined by high pressure liquid chromatography, was observed after one hour. Four hours later the serum level was 0.3 mg/l. Using microbiological methods no statistically significant difference was obtained in comparison with the chromatography results. Some of the sera stored at -75 degrees C for four weeks showed a substantial loss of activity of cefaclor.

Administration, Oral↗
PubMed1979

Quantitative determination of praziquantel in body fluids by gas liquid chromatography.

Praziquantel was determined in body fluids by gas liquid chromatography as follows: A known amount of an internal standard and 0.1 N sodium hydroxide solution was added to the sample to be analyzed. After extraction with methyl acetate/diisopropyl ether = 30/70, the organic extract was evaporated, the residue taken up in methylacetate and an aliquot injected for glc analysis. Separation was accomplished on a OV3 silicon oil phase, and for detection and quantitation, a thermoionic FID sensitized for nitrogen-containing compounds was used. The determination limit in serum is about 0.01 micrograms/ml. The relative standard deviation for serum concentrations of 0.1 micrograms/ml was found to be 4.5%.

Chromatography, Gas↗
PubMed1978

Clinical pharmacology in normal volunteers of praziquantel, a new drug against schistosomes and cestodes. An example of a complex study covering both tolerance and pharmacokinetics.

The tolerance of Praziquantel (2-cyclohexylcarbonyl-1, 3, 4, 6, 7, 11b-hexahydro-2H-pyrazino-[2, 1-a]isoquinoline-4-one) in oral doses of 1 X 20 mg/kg, 1 X 50 mg/kg, 3 X 10 mg/kg and 3 X 25 mg/kg body weight (tau = 4 h) was tested in a complex study involving 36 healthy volunteers. In addition to the usual assessment of clinical chemistry, haematology, coagulation physiology, urinalysis, clinico-physiological examination including EEG, and medical examination, clinico-psychological parameters were also recorded and special neurological investigations were performed. No clinically relevant changes were found in any of the laboratory parameters, nor in the medical-neurological or clinico-physiological examinations. Based on a few clinico-psychological parameters and subjective comments, the largest daily dose tested (3 X 25 mg/kg = 75 mg/kg) produced a slight, transient disturbance in general well-being, which was barely detectable on objective clinical examination. The pharmacokinetic behaviour was dominated by rapid metabolism and pronounced first-pass metabolism of praziquantel, which greatly limits the value of results obtained by GC analysis of unchanged drug in serum. The peak concentration in serum was reached after 1--2 h, and the elimination half-life for the period 2--8 h was 1--1.5 h.

Adult↗
PubMed1976

[Pharmacokinetics of pramiverine in rats, dogs, and monkeys (author's transl)].

The pharmacokinetic properties of 4,4-diphenyl-N-isopropyl-cyclohexylamine-hydrochloride (pramiverine, Sistalgin) in Wistar rats, beagles, and rhesus monkeys are described. After i.v. injection of 14C-labelled pramiverine incorporation of radioactivity from the blood into organs and tissues is rapid. The radioactivity is eliminated from the blood with a half-life of 4-7 h in rats, 17-32 in dogs, and 8-26 h in rhesus monkeys. Unmetabolized pramiverine, in contrast, is eliminated much faster, the half-lives are 2 h in dogs and 3 h in rhesus monkeys. After oral administration maximum serum concentrations are reached after 4 h in rats and dogs and 2 h in rhesus monkeys. The drug undergoes a marked first-pass effect in the liver. In all species pramiverine is absorbed rapidly from the gastro-intestinal tract. Drug and/or metabolites are eliminated in rats and dogs predominantly with feces, in monkeys with urine, independent of the route of administration. During a 6 h interval, biliary elimination was found to be 50% after i.v. and 30% after oral administration. 90% of pramiverine present in the blood plasma is reversibly bound to proteins.

Administration, Oral↗
PubMed1976

[Metabolism of pramiverine (author's transl)].

The metabolite patterns of 4,4-diphenyl-N-isopropyl-cyclohexylamine-hydrochloride (pramiverine, Sistalgin) in urine, feces, bile and serum of Wistar rats, beagle dogs, rhesus monkey and man were analyzed with radio thin-layer chromatographic techniques. The structures of six pramiverine metabolites were elucidated. Pramiverine is eliminated unchanged in only minute amounts via the renal, the biliary and the fecal route. Consequently an almost quantitative absorption and metabolism takes place. Metabolite patterns in serum and urine differ considerably indicating that some of the metabolites are excreted preferentially by the kidney while others are reabsorbed to various degrees. The identified metabolites are products of dealkylation, deamination and hydroxylation reactions.

Animals↗
PubMed1976

[Gaschromatographic determination of pramiverine in body fluids (author's transl)].

A method for the quantitative determination of 4,4-diphenyl-N-isopropyl-cyclohexylamine-hydrochloride (pramiverine, Sistalgin) in serum and urine was developed. After the addition of a known amount of a pramiverine homolog as an internal standard the basic pramiverine and standard are separated from acidic and neutral constituents of the sample by the following extraction sequence: Extraction from the alkalized sample into n-hexane/ethyl acetate; reextraction into 0.1 N hydrochloric acid; alkalisation of the hydrochloric acid phase and reextraction into n-hexane/ethyl acetate. The constituents of this final extract are concentrated and separated on an OV 17 silicon oil phase. A thermoionic nitrogen-selective flame ionisation detector was used. The determination limit for 5-ml serum samples is about 0.5-1 ng pramiverine/ml. For samples in the concentration range of 4 ng/ml a relative standard deviation of 12% was found.

Benzhydryl Compounds↗