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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 64 (1990), S. 1-6 
    ISSN: 1432-0738
    Keywords: Non-steroidal anti-inflammatory drugs ; Pharmacokinetics ; Biodistribution ; Absorption ; Gastric mucosal damage ; Azapropazone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since most non-steroidal anti-inflammatory drugs (NSAIDs) contain only one obvious ionisable group at physiological pH levels then they may be easily identified as having either acidic or basic character. Basic NSAIDs are simply non-acidic NSAIDs capable of accepting a proton within the physiological pH range. Within this range, however, a few NSAIDs contain two obvious ionisable groups, one acidic and the other basic. Such compounds should be described as amphiprotic, and include NSAIDs such as 4- and 5-amino substituted salicylic acids, niflumic acid, amfenac, WY 18251, and azapropazone. The aqueous ionisation equilibrium of such compounds is complex and is described by two macroscopic ionisation constants. Evidence has accumulated during the last decade to support the view that the pharmacokinetic behaviour of NSAIDs contributes not only decisively to their therapeutic effects but also to the type and incidence of their side-effects.A priori, using a physico-chemical argument, certain amphiprotic NSAIDs should be better tolerated by the gastric mucosa than the classical acidic compound. Of those NSAIDs commercially available in the United Kingdom azapropazone remains the only one for which amphiprotic behaviour has been described. Following our examination of available data for azapropazone we conclude that the use of amphiprotic compounds represents a logical approach towards solving the problem of NSAID-induced gastric mucosal damage.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0738
    Keywords: Non-steroidal anti-inflammatory drugs ; Pharmacokinetics ; Biodistribution ; Absorption ; Gastric mucosal damage ; Proquazone ; BW755C ; MDL 035 ; Flufenamic acid ; Fenclofenac ; Salicyclic acid ; Diflunisal ; Azapropazone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Evidence has accumulated during the last decade to support the view that the pharmacokinetic behaviour of non-steroidal anti-inflammatory drugs (NSAIDs) contributes not only decisively to their therapeutic effects but also to the type and incidence of their side effects. It has been shown that NSAIDs reach particularly high concentrations in those compartments in which they cause effects and side effects. Specifically, the data reviewed herein indicate that the accumulation of NSAID within gastric mucosal cells a priori is a principal factor associated with the intervention of intracellular biochemical events and resultant gastric mucosal damage. To a large extent this behaviour is according to the precepts of classical absorption theory; in this respect the limitations of such theory are examined. Our survey further indicates that the failure of certain NSAIDs to significantly reduce gastric mucosal levels of prostaglandins (PG) in vivo may reflect pharmacokinetic differences between NSAIDs rather than tissuespecific differences in their potency as inhibitors of cyclooxygenase.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 422-427 
    ISSN: 0899-0042
    Keywords: 2-arylpropionates ; enantiomers ; stereoselectivity ; chiral inversion ; pharmacokinetics ; bile-duct cannulated rats ; biliary excretion ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To examine the stereoselectivity of biliary excretion, the optically pure enantiomers of ketoprofen (KT), ibuprofen (IBU), and flurbiprofen (FLU) were intravenously administered to normal and bile duct-cannulated rats at 10 mg/kg. The recovery of total KT in bile was significantly higher after administration of (S)-KT than after (R)-KT [90.1 ± 3.5% vs 68.8 ± 8.2%, n =3, P 〈 0.05]. In normal rats the terminal half-life of (R)-KT was significantly shorter than that of (S)-KT after administration of (R)-KT (2.2 ± 0.6 h vs 14.3 ± 4.9 h, n = 3, P 〈 0.05). The terminal half-life of both enantiomers was significantly shorter in rats with continuous bile drainage as compared to normal rats. No significant differences in pharmacokinetic parameters could be found between both enantiomers in bile duct-cannulated animals. The total amount of IBU in bile was slightly higher after administration of (S)-IBU than after (R)-IBU administration. The percentage of (R)-IBU after (R)-IBU administration, however, was very low [(R)-IBU: 1.5 ± 0.9%, (S)-IBU: 23.4 ± 5.8%]. In normal rats the clearance of (R)-IBU was significantly higher as compared to (S)-IBU. Differences in pharmacokinetic parameters between normal and bile duct-cannulated rats were not statistically significant due to high interindividual variability. The total recovery of FLU, which was excreted in bile to a lower extent than either KT or IBU, also tended to be greater after S-enantiomer administration. Only small amounts of (S)-FLU could be recovered in bile after (R)-FLU administration. The pharmacokinetic parameters did not differ significantly between (R)- and (S)-FLU or between normal and bile duct-cannulated rats due to its low inversion rate and low excretion via bile. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 165-169 
    ISSN: 0899-0042
    Keywords: ibuprofen ; enantiomer ; stereoselectivity ; chiral inversion ; pharmacokinetics ; dog ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Inversion of inactive (R)-ibuprofen to active (S)-ibuprofen has been suggested to occur presystemically only. In order to investigate the site of inversion in dogs we administered both enantiomers either intravenously or intraduodenally (10 mg/kg) to adult, male beagle dogs (n = 3) in a crossover design. Plasma, urine, and bile were collected for up to 6 h and analyzed stereospecifically by HPLC, according to a previously published method. Pharmacokinetic parameters were calculated using a linear computer program. Absorption after intraduodenal administration occurred rapidly, resulting in maximum plasma concentrations 0.2 h after giving the enantiomer. Approximately 70% of the (R)-enantiomer (according to AUC) was inverted to the S-enantiomer independent of route of administration. No R-ibuprofen could be detected in plasma after (S)-ibuprofen administration. Mean residence time was found to be 2 to 3 times longer for (S)-than for (R)-ibuprofen. Total systemic clearance from plasma was twice as high for (R)- than for (S)-ibuprofen. There were no differences between plasma clearances after intravenous and intraduodenal administration. Between 8 and 17% of dose was recovered in bile [especially as free and conjugated (S)-ibuprofen] and 3-12% in urine [as (S)-ibuprofen, hydroxy- and carboxyibuprofen, free and conjugated forms]. Small amounts of (R)-ibuprofen were detected in bile after intraduodenal administration of (R)-ibuprofen only (1.8% of dose). In short, the unidirectional inversion of R-ibuprofen appears to occur systemically rather than presystemically in dogs.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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