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  • bioavailability  (3)
  • theophylline  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 23 (1982), S. 235-240 
    ISSN: 1432-1041
    Keywords: ergotamine ; pharmacokinetics ; migraine ; plasma drug levels ; i.v. administration ; i.m. administration ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics of ergotamine has been investigated in migrainous patients using a new, specific, sensitive HPLC assay (detection limit 100 pg/ml plasma). 10 patients were given ergotamine tartrate 0.5 mg i.v. and 5 of them received the same dose i.m. 2–3 weeks later. Blood samples were collected for up to 54 h following administration and the plasma concentration were analysed. After intravenous administration the plasma ergotamine declined rapidly, with an initial distribution half-life of 3 min followed by a mean terminal half-life of 1.86 h (range 90–155 min). The mean total plasma clearance was 11.0 ml kg−1 min−1, and the volume of distribution (Vdβ ) was 1847.6 ml kg−1. Individual t1/2β showed a positive linear correlation with the individual Vdβ . The intramuscular absorption of ergotamine was rapid and maximum plasma levels were usually obtained 10 min following administration. The biological availability was incomplete and variable at 46.6% (range 28.3–60.8%).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 24 (1983), S. 89-92 
    ISSN: 1432-1041
    Keywords: theophylline ; kwashiorkor ; marasmus ; children ; nutritional status ; pharmacokinetics ; dosage recommendation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of theophylline in Ethiopian children of differing nutritional status was studied. In 8 children of normal weight, the t1/2β (4.93 h) plasma clearance (1.22 ml/min/kg and Vd area (504 ml/kg) were similar to those of Swedish children of normal weight. In children with marasmus or kwashiorkor there was an increased volume of distribution. The increase in Vd was reflected in an increased biological half-life, in spite of a slight but not significant increase in clearance in both of these groups of children. The pharmacokinetic changes in clearance and volume of distribution found in malnutrition should counteract each other, so from a clinical point of view theophylline can be given to Ethiopian children according to the standard dosage recommendation, regardless of nutritional status.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 16 (1979), S. 133-139 
    ISSN: 1432-1041
    Keywords: theophylline ; asthma ; pharmacokinetics ; children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Six children, aged 2 months – 4 years, received theophylline 5–6 mg/kg intravenously. Its disposition could be described by a two-compartment open model, the mean serum half life (t1/2 β) was 3.75 h, i. e., shorter than in adults, but there was a considerable interindividual variation (1.8–7.0 h, in one patient 13.3 h). Thirteen children (2 months – 4 years) received theophylline suppositories in a dose of 3.8–5.0 mg/kg, and ten (6 months – 4 years) in a dose of 8.4–14.5 mg/kg. Absorption was slow (mean half-time 43 min), incomplete and variable (biological availability 8–100%, mean 80%). Only four of the patients given the higher dose and none given the lower dose reached a therapeutic serum concentration (10–20 µg/ml). Nine children (6 months – 4 years) received rectal enemas of theophylline 4.1–9.2 mg/kg. Absorbtion was rapid (mean half-time 5.5 min) and biological availability averaged 100%. Six patients reached a serum concentration within the therapeutic range. Using the mean values of the calculated pharmacokinetic parameters, rectal enemas providing a dose of theophylline of 6–8 mg/kg t. i. d. were computed to give serum concentrations between 8–20 µg/ml, without producing too high a level during the absorption phase.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1041
    Keywords: theophylline ; caffeine ; apnoea ; aminophylline ; infant ; plasma level ; plasma clearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma concentrations of caffeine and theophylline were simultaneously determined in 17 preterm infants after oral administration of aminophylline for treatment of apnoea. The ratio of caffeine/theophylline concentration in plasma increased during the first 2 weeks of treatment, owing to the longer time required for caffeine than for theophylline to reach steady state. The caffeine/theophylline ratio at steady state was 0.57±0.03 (mean±SE). Thus, caffeine contributed significantly to the total methylxanthine load in the infants. The plasma clearance of theophylline was calculated from the plasma steady state concentrations. In 3 preterm infants treated with oral aminophylline, repeated sampling showed an approximately linear increase in clearance with time from 16.8±0.4 (mean±SE) at a postnatal age of 6–11 days to 30.9±2.5 ml/kg/h at 64–69 days. In 1 full-term infant treated with oral theophylline from 3.5 to 11.5 months of age, the plasma clearance of theophylline increased in a roughly linear manner, reaching a plateau of about 100 ml/kg/h at 6–7 months of age. This corresponds to the clearance found in 1–4 year old infants.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 26 (1984), S. 197-207 
    ISSN: 1432-1041
    Keywords: furosemide ; bioavailability ; pharmacokinetics ; oral administration ; i.v. administration ; drug absorption ; moment analysis ; food effect ; dissolution effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Furosemide 40 mg was administered to 8 healthy subjects as an i.v. bolus dose, as 1 tablet in the fasting state, and as 1 tablet and a solution after food intake. The i.v. data gave a total body clearance of 162±10.8 ml/min and a renal clearance of 117±11.3 ml/min; the volume of distribution at steady state was 8.3±0.61. Oral administration gave a bioavailability of the tablet (fasting) of 51%. Food intake slightly reduced the bioavailability, but not to a significant extent. There was no significant difference in availability between the tablet and the solution. Moment analysis gave a mean residence time after the i.v. dose, MRTi.v., of 51±1.5 min. The mean absorption times (MAT) for all oral doses were significantly longer than the MRTi.v., indicating absorption rate-limited kinetics of furosemide. On average, food delayed the absorption by 60 min. The MAT for the tablet in the postprandial state was significantly longer than for the solution, indicating dissolution rate-limited absorption of the tablet.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1041
    Keywords: Ampicillin ; bioavailability ; pharmacokinetics ; branded products ; proprietary preparations ; capsule formulation ; tablet formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and bioavailability of three different brands of ampicillin were studied in 10 volunteers. After intravenous administration ampicillin can be described adequately by a two-compartment open pharmacokinetic model. The half-life during the α-phase was 9 min and the β-half-life was in the range 50–60 min, independent of the mode of administration. Absolute bioavailability was determined from the ratio of the areas under the serum concentration curves obtained after oral and intravenous administration of equal doses. Bioavailability was also estimated by analysis of variance. The results indicated absolute availability of the three products of 39–54%. One of the products, a capsule formulation, showed a significantly lower bioavailability than the others, which were tablet formulations.
    Type of Medium: Electronic Resource
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