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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 54 (1998), S. 549-553 
    ISSN: 1432-1041
    Keywords: Key words Dipyrone ; Cerebrospinal fluid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: Dipyrone is a veteran analgesic and antipyretic drug. After oral administration it is rapidly converted by hydrolysis to 4-methylaminoantipyrine (MAA), which is further metabolized to 4-formylaminoantipyrine (FAA), 4-aminoantipyrine (AA) and 4-acetylaminoantipyrine (AAA). It is still debated whether the site of dipyrone action is in the central nervous system or in the periphery. The purpose of this study was to assess whether dipyrone metabolites cross the blood-brain barrier (BBB) when administered systemically. Methods: Twenty-eight patients undergoing diagnostic lumbar puncture (LP) were randomly assigned to receive two 0.5-g dipyrone tablets either 30 min, 1, 1.5, 2, 4, 6, 8 h or 12 h before the lumbar tap. A 5-ml blood sample was drawn concomitantly. Results: All four metabolites were found in the cerebrospinal fluid (CSF). Their appearance in the CSF lagged but followed that found in the plasma. Mean CSF/plasma ratios were 0.40 (for samples taken between 0.5–2 h) and 0.83 (for samples taken between 4–12 h) for MAA, 0.62 for AA, 0.55 for FAA and 0.40 for AAA (for all samples). Significant correlation was found between plasma and CSF concentrations for MAA, AA, FAA and AAA. Conclusion: The concentration-time course of dipyrone metabolite CSF concentrations are in agreement with that of their plasma concentrations and the analgesic effect of dipyrone.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 55 (1999), S. 475-478 
    ISSN: 1432-1041
    Keywords: Key words Cyclosporin ; Dipyrone ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Background: A large number of drugs have been shown to affect the metabolism of cyclosporin A (CSA) and, since cyclosporin is characterized by a narrow therapeutic range, the consequences of such drug interactions may often be of clinical importance. Objective: To evaluate the effect of short-term administration of dipyrone on steady state CSA pharmacokinetics. Methods: Six kidney- and two heart-transplanted patients on chronic CSA therapy participated in this study, which consisted of two 4-day study periods separated by 3-week washout periods. The patients received, in addition to their usual drugs, dipyrone 500 mg or placebo t.i.d., as identical-looking tablets, and the order of administration was randomized. CSA concentrations were measured in whole blood by means of radio-immunoassay (CYCLO-Trac SP) daily during the study periods and periodically over 24 h on the fourth study day. Results: CSA concentrations over time were reduced after dipyrone (ANOVA, P 〈 0.01), but statistical significance was noted only at 2, 4, 5 and 10 h after drug intake (P 〈 0.05). Peak CSA concentration was not altered by dipyrone, but the time required to reach maximal concentration was longer with dipyrone treatment than with the placebo (3.8 ± 2.6 h vs 2.1 ± 0.6 h, P 〈 0.05). No consistent changes were noted for CSA trough level, elimination half-life and area under the concentration–time curve from 0 h to 12 h. Separate analysis of the kidney transplanted patients yielded similar results. Conclusions: Short-term administration of dipyrone is associated with a mild decrease in CSA blood concentration, which is most prominent in the first few hours after drug intake. In practice, no dose adjustment of CSA seems to be indicated during a short course of dipyrone treatment.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 67-71 
    ISSN: 1432-1041
    Keywords: dipyrone ; dipyrone metabolites ; human protein binding ; analgesic antipyretic drugs ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Four metabolites of dipyrone, 4-methyl-aminoantipyrine (MAA), 4-aminoantipyrine (AA), 4-formylaminoantipyrine (FAA) and 4-acetylamino-antipyrine (AAA) can be identified in human plasma after its oral administration. The plasma protein binding of the metabolites in samples from 20 healthy volunteers was determined by ultrafiltration. None of the metabolites were found to be extensively bound to plasma proteins. The binding of MAA and AA was relatively higher than of FAA and AAA, as expected from their chemical structure. The mean percentage plasma protein binding was 57.6% for MAA, 47.9 for AA, 17.8 for FAA and 14.2% for AAA. The correlation between the unbound concentration in plasma and the total concentrations of MAA, AA, FAA and AAA was linear. No association was evident between the total protein plasma concentration and the extent of binding. The possible therapeutic implications related to protein binding of several analgesic and non-steroidal anti-inflammatory drugs are discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 34 (1988), S. 105-107 
    ISSN: 1432-1041
    Keywords: dipyrone ; methylaminoantipyrine ; food interaction ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Twelve healthy volunteers were given a single oral dose of dipyrone 1 g, once while fasting and once after a standard breakfast. Plasma levels of the active dipyrone metabolite — Methylaminoantipyrine (MAA) were measured and the calculated pharmacokinetic parameters were compared. Taking dipyrone with food resulted in a small delay in the mean time to peak from 1.5 h to 1.9 h (p〈0.01). However, there was no significant difference in AUC, Cmax or Kelim between fasting and nonfasting conditions. The rate of absorption, expressed as the mean Kabs, was somewhat slower in the nonfasting state, but not significantly so. It is suggested that dipyrone may be taken regardless of the times of eating.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 47 (1995), S. 525-530 
    ISSN: 1432-1041
    Keywords: Antipyrine disposition ; Obesity ; pharmacokinetics ; oxidative metabolism ; weight reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Following an overnight fast and 2 days of abstention from caffeine, a single 1.0-g oral dose of antipyrine was administered to 20 obese but otherwise healthy subjects (group A) and 11 healthy volunteers (group B). Weight, Body Mass Index (BMI) and % of Ideal Body Weight (IBW) were significantly greater in the obese than in the lean group. (Mean 110.4 vs 62.7 kg; 38.5 vs 22.3 kg · m−2 and 181vs 106 % respectively). In a subgroup of 6 obese subjects (group C) antipyrine was given again 11.3 months later after a 29.8 kg mean weight loss. Antipyrine apparent volume of distribution (V) and elimination half-life (t 1/2) were significantly greater in the obese than in the lean group (V 49.9 vs 34.3 l respectively; t 1/2 15.5 vs 12.0 h respectively), but its clearance rate (CLo) values were similar. V corrected for total body weight was significantly reduced in group A than in group B (0.45 vs 0.55 l · kg−1 respectively). Stratified comparison of antipyrine pharmacokinetics between obese and lean subjects according to age, gender and smoking habits did not alter the overall results. In group C, weight reduction was associated with a significant decrease in antipyrine V (from 51.8 to 47.5 l) and t 1/2 (from 15.1 to 12.7 h), and a non-significant increase in antipyrine CLo. We conclude that in severely obese subjects, antipyrine total V is mildly increased but V corrected for total body weight is significantly decreased. In addition, obesity is associated with a slight prolongation of antipyrine t 1/2 whereas its CLo is unaltered. These findings may indicate that obesity, even in its extreme form, has a negligible effect on the oxidative metabolic capacity of the liver.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 27 (1984), S. 453-458 
    ISSN: 1432-1041
    Keywords: dipyrone ; metabolism ; metabolite pharmacokinetics ; acetylation polymorphism ; healthy volunteers ; dapsone phenotyping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of the dipyrone metabolites 4-methylaminoantipyrine (MAA), 4-aminoantipyrine (AA), 4-formylaminoantipyrine (FAA) and 4-acetylaminoantipyrine (AAA) were evaluated following the administration of a single oral 1.0 g dose of dipyrone to 23 healthy volunteers. Twelve were slow and 11 were rapid acetylators as previously determined by dapsone phenotyping. For MAA and FAA the mean peak plasma concentrations were 10.5±2.8 µg/ml and 2.1±0.8 µg/ml and the half-lives were 3.3±1.0 and 10.1±1.8 h, respectively. No significant difference was found between rapid and slow acetylators in MAA and FAA kinetics. For AA, the mean peak plasma concentrations were 2.7±0.6 and 1.6±0.7 µg/ml (p〈0.01), the peak times 6.7±2.1 and 3.1±1.1 h (p〈0.01) and the half-lives were 5.5±1.0 and 3.8±1.2 h in slow and rapid acetylators, respectively. For AAA, the mean peak plasma concentrations were 1.6±0.4 and 4.4±1.1 µg/ml (p〈0.01) and the peak time 16.1±5.1 and 10.0±2.6 h (p〈0.01) in slow and rapid acetylators, respectively. There was no difference in the elimination half-life between the two groups (10.6±2.2 h). Thus, it has been demonstrated that the AAA/AA ratio is an indicator of the acetylation phenotype, as it is closely correlated with that determined by dapsone (r=0.895, p〈0.0005).
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 26 (1984), S. 171-176 
    ISSN: 1432-1041
    Keywords: dipyrone ; thromboxane A2 ; platelet aggregation ; arachidonic acid ; prostaglandin synthetase ; PG synthetase inhibition ; collagen ; dipyrone metabolism ; plasma levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Platelet aggregation and thromboxane A2 (TXA2) production induced by arachidonic acid and collagen were studied in 10 healthy volunteers prior to and at various times after the oral administration of a single dose of 1 g dipyrone. The plasma concentrations of four dipyrone metabolites were also determined. Dipyrone inhibited platelet aggregation and markedly decreased TXA2 synthesis induced by threshold concentrations of both agonists. Maximal inhibition was noted 1 hour after drug administration and in some subjects it lasted as long as 72 h. At all times the effect of the drug could be abolished by increasing the concentration of the agonist. This is consistant with a competitive inhibitory effect of dipyrone on prostaglandin synthetase activity. The mean plasma concentration of the main dipyrone metabolite methylaminoantipyrine at 1 h was 11 µg/ml. There was no correlation between individual plasma levels and the parameters of platelet function. At 24 h the mean concentration of each of the metabolites studied was up to 1 µg/ml, and these levels, too, did not correlate with the biological effect of the drug.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 30 (1986), S. 359-361 
    ISSN: 1432-1041
    Keywords: dipyrone ; metabolites ; excretion in milk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Breast milk and plasma levels of dipyrone metabolites in 8 mothers given a single oral dose of the drug were determined by HPLC. Four metabolites were demonstrated by the analytical method: 4-methylaminoantipyrine (MAA), 4-aminoantipyrine (AA), 4-formylaminoantipyrine (FAA) and 4-acetylaminoantipyrine (AAA). A good correlation was found between the plasma and milk concentrations of the metabolites. The mean (±SD) milk to plasma concentration ratios were: MAA=1.37±0.28, AA=1.15±0.40, FAA=1.03±0.09, AAA=0.97±0.24. The disposition pattern of the dipyrone metabolites in milk was studied in two mothers. None of the metabolites was detectable 48 h after drug administration.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 42 (1992), S. 187-191 
    ISSN: 1432-1041
    Keywords: Dipyrone ; Acetylation phenotype ; metabolism ; pharmacokinetics ; urinary excretion ; metabolite clearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The formation and urinary excretion of the dipyrone metabolites, methylaminoantipyrine (MAA), aminoantipyrine (AA), formylaminoantipyrine (FAA) and acetylaminoantipyrine (AAA) were determined following administration of a single oral 1.0 g dose of dipyrone to 12 healthy volunteers. The AAA/AA plasma ratio showed that 3 subjects were slow and 9 were rapid acetylators. Pharmacokinetic parameters were determined separately for each group. A good correlation was found between the plasma and urine AAA/AA ratios. The renal clearance of the four metabolites was similar for both phenotypes. A significant difference in the rate of formation of dipyrone metabolites was found for AA, 0.25 (slow) vs 0.1 ml·min−1·kg−1 (rapid), and for AAA 0.75 (slow) vs 7.53 ml·min−1·kg−1 (rapid). There were comparable differences between slow and rapid acetylators in the AUC and the urinary excretion extrapolated to infinity for AA and AAA. The present results show that the kinetics of dipyrone metabolites in plasma and urine can provide a useful measure of the activity of the enzymes involved in their production.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 36 (1989), S. 513-516 
    ISSN: 1432-1041
    Keywords: dipyrone ; methylaminoantipyrine ; aging ; renal function ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of the dipyrone metabolite, 4-metylaminoantipyrine (MAA) was evaluated, following the administration of a single oral dose of dipyrone 1.0 g to 12 young (21–30 years) and 9 elderly (73–90 years) healthy volunteers. Maximal concentration, time to peak and absorption rate of MAA were similar for both groups. The elimination half-life was 2.6 (0.2) h for the young and 4.5 (0.5) h for the elderly subjects. Total clearance of MAA, corrected for lean body mass (LBM), was lower in the elderly than in the young 2.65 vs 3.97 ml·min−1·k−1 LBM. There was no differences between the groups in the apparent volume of distribution. A good correlation was found between the total body clearance of MAA and the creatinine clearance, which was also reduced in the elderly (r=0.61).
    Type of Medium: Electronic Resource
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