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Biomedical subjects

H Spahn

Publications and source records attributed to H Spahn.

At least 73 records · Page 4Linked to original sources
PubMed1983

Accumulation and adverse effects of metoprolol and propranolol after concurrent administration of cimetidine.

Pharmacokinetics of metoprolol, propranolol and atenolol were investigated in six healthy volunteers following 7 days of oral monotherapy with these drugs and after 7 days concurrent administration of each of these betareceptor antagonists with cimetidine. Application of cimetidine did not lead to any interaction with atenolol, whereas mean peak plasma levels of metoprolol were increased by 70%, and those of propranolol by 95% due to concurrent administration of cimetidine (p less than 0.05). The AUC of the two last mentioned beta blockers behaved similarly (p less than 0.05). Measurement of exercise-induced tachycardia on the 6th day of administration showed no differences between monotherapy with the beta blocker and combined treatment with each of them and cimetidine. Except for one volunteer who complained of anxiety, weakness and sweating on the 6th day of cimetidine/metoprolol administration, no adverse effects could be observed during the combination therapy with cimetidine and the beta blockers or in monotherapy with beta blockers.

Adult↗
PubMed1982

Interaction of metoprolol, propranolol and atenolol with concurrent administration of cimetidine.

Pharmacokinetics of metoprolol, propranolol, and atenolol were investigated in six healthy volunteers following 7 days of oral monotherapy with these drugs, and after 7 days concurrent administration of each of these betareceptor antagonists with cimetidine. Application of cimetidine did not lead to any interaction with atenolol, whereas mean peak plasma levels of metoprolol were increased by 70%, and those of propranolol by 95% due to concurrent administration of cimetidine (P less than 0.05). The plasma level time curve (AUC) of the two above-mentioned beta blockers behaved similarly (P less than 0.05). Other kinetic parameters of these two drugs were not influenced to a statistically significant extent by cimetidine, despite the tendency for the elimination half-life of metoprolol and propranolol to be prolonged when cimetidine is added. Measurement of exercise-induced tachycardia on the sixth day of administration showed no differences between monotherapy with the beta blockers and combined treatment with each of them together with cimetidine. Apart from one volunteer who complained of anxiety, weakness, and sweating on the sixth day of cimetidine/metoprolol administration, no adverse effects could be observed during the combination therapy with cimetidine and the beta blockers, nor during monotherapy with beta blockers.

Adult↗
PubMed1982

[Determination of feprazone and one of its metabolites in human plasma after high-performance liquid chromatographic or thin-layer chromatographic separation].

Two procedures suitable for pharmacokinetic routine analysis are described for the simultaneous determination of feprazone and one of its metabolites (DA 3505) in plasma samples. After extraction from acidified plasma feprazone and DA 3505 are determined by measuring UV absorbance after thin-layer chromatographic (TLC) separation (reversed-phase TLC plates; methanol--water--formic acid) or high-performance liquid chromatographic (HPLC) separation (silica gel column; hexane--tetrahydrofuran--acetic acid). Limits of detection are 0.1 microgram feprazone per ml plasma and 0.2 microgram of its metabolite per ml plasma using the HPLC method. Concentration down to about 0.5 microgram/ml plasma of both compounds can be determined using the TLC method.

Chromatography, High Pressure Liquid↗
PubMed1981

[Determination of bumadizone, phenylbutazone and oxyphenbutazone in human plasma by high-performance liquid chromatography (author's transl)].

HPLC methods are described to determine bumadizone, phenylbutazone and oxyphenbutazone in human plasma. The procedure for the determination of phenylbutazone and oxyphenbutazone is based on a microphase extraction and especially suitable for routine analyses because of its simplicity and rapidity. 0.5 microgram of the compounds per milliliter plasma can easily be determined; the relative standard deviations of the methods are between 0.7 and 4.4% at therapeutic plasma concentrations.

Chemical Phenomena↗
PubMed1981

[Comparison of bumadizone-, phenylbutazone- and oxyphenbutazone-plasma levels after a single oral dose of phenylbutazone and of bumadizone, respectively (author's transl)].

Bumadizone-calcium-semihydrate and phenylbutazone were given orally to two groups (I and II) consisting of 6 persons each; plasma levels of bumadizone, phenylbutazone and oxyphenbutazone were determined over a period of 384 h. For bumadizone a plasma half-life of 6.9 h was found, maximum plasma levels were reached after 1-6 h varying from 27 to 46 microgram/ml. Phenylbutazone- and oxyphenbutazone-AUC-values were compared between the two groups.

Administration, Oral↗
PubMed1969

[Basic nursing].

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Nursing Care↗
PubMedDate not supplied

Influence of inflammatory disease on the clinical pharmacokinetics of atenolol and metoprolol.

The influence of inflammatory disease on the pharmacokinetics of atenolol and metoprolol was investigated after administering single oral 100 mg doses of the drugs to six subjects. Each subject had a respiratory tract infection with an erythrocyte sedimentation rate (ESR) of over 20 mm in the first hour and a body temperature of at least 38.5 degrees. Since the subjects subsequently received atenolol and metoprolol when they were healthy, each person acted as his own control. Inflammatory disease had no influence on the kinetics of metoprolol. In contrast, mean peak plasma levels and AUC for atenolol were significantly lower, both by about 40 per cent, during infectious disease compared to the healthy state (p less than 0.05), where as renal clearance of atenolol slightly increased from 110.8 +/- 14.7 ml min-1 in the healthy state to 128 +/- 21.6 ml min-1, when the ESR's were elevated. The elimination half-life of atenolol, about 10 h, was not affected by the health status of the subjects. Reduced absorption in the gastro-intestinal tract and enhanced elimination of atenolol from plasma might account for the decreased AUC and peak plasma levels of the drug during inflammatory disease.

Adult↗
PubMedDate not supplied

Influence of probenecid on the urinary excretion rates of the diastereomeric benoxaprofen glucuronides.

A major biotransformation pathway for many NSAIDs from the group of optically active 2-arylpropionic acids is the conjugation with D-glucuronic acid, forming diastereomers. These conjugates of the S-(+)-and the R-(-)-enantiomers can be separated directly, e.g., by ion-pair chromatography on a C18-column using a mixture of tetrabutylammonium buffer pH 2.5 and acetonitrile as mobile phase. In man about 40% of the dose was recovered in urine as glucuronides (ratio S:R = 2.2) within 96 hours of p.o. administration of racemic drug. When probenecid, which is known to influence the elimination of several acidic drugs, was administered in addition, the amount excreted as glucuronides during 4 days was clearly reduced. Furthermore, the enantiomeric ratio was changed significantly, possibly because of an increase of stereoinversion due to the reduced drug clearance.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMedDate not supplied

Stereoselective disposition of carprofen, flunoxaprofen, and naproxen in rats.

The stereoselective dispositions of carprofen, flunoxaprofen, and naproxen were studied in rats after i.v. administration of racemate (11 mumol/kg) or enantiomer (5.5 mumol/kg). The total clearances of the (R)-enantiomers of carprofen and flunoxaprofen were significantly greater than those of the (S)-enantiomers. The clearance of (S)-naproxen was similar to the value for (R)-naproxen. There were no marked differences in steady-state volume of distribution between (R)- and (S)-enantiomers for carprofen, flunoxaprofen, or naproxen. The (R)- to (S)-enantiomer inversion ratio for flunoxaprofen in rats was 0.54. The ratios for naproxen and carprofen were 0.02 and 0.003, respectively. Biliary excretion of (R)-carprofen and of its glucuronide were higher than those of the (S)-enantiomer and its glucuronide. In contrast, biliary excretion of the (S)-enantiomers of flunoxaprofen, naproxen, and of their glucuronides were greater than those of their antipodes. Insignificant amounts of the parent enantiomers and of the glucuronides of these three drugs were excreted in urine. These results indicate that there is a wide variation in the extent of inversion at a chiral center for these three 2-arylpropionates and in the stereoselective disposition of their acyl glucuronides.

Animals↗