Prostaglandin biosynthesis in rabbit kidney medulla: Inhibition in-vitro vs. in-vivo by aspirin, indomethacin and meclofenamic acid

Yedidya Gafni, Michal Schwartzman, Amiram Raz

Research output: Contribution to journalArticlepeer-review

Abstract

The non-steroidal anti-inflammatory drugs aspirin, indomethacin and meclofenamic acid were compared for their potency and duration of inhibition of prostaglandin biosynthesis in rabbit kidney medulla. Indomethacin and meclofenamic acid showed equal potency of inhibition in-vitro (IC50 0.88 μM and 0.85 μM respectively) while aspirin was a much weaker inhibitor (IC50 120 μM). In-vivo, indomethacin was the most powerful inhibitor (ID50 0.034 mg/kg) followed by meclofenamic acid (0.45 mg/kg) and aspirin (2.35 mg/kg). Studies on the duration of in-vivo inhibition by these compounds showed the effect of indomethacin and meclofenamic acid to be completely reversed within 4-6 hours. In contrast, return of kidney prostaglandin biosynthetic activity following aspirin inhibition is very slow and significant inhibition is still present 48 hours after a single aspirin injection. The inhibitory effect of aspirin in-vivo could be blocked by pretreatment with indomethacin, indicating that both drugs interact with related sites on the cyclo-oxygenase enzyme. The irreversible inhibition of the cyclo-oxygenase by aspirin as demonstrated in studies of other investigators suggests that the return of kidney prostaglandin synthetase activity after aspirin inhibition represents synthesis of new cyclo-oxygenase protein.

Original languageEnglish
Pages (from-to)759-772
Number of pages14
JournalProstaglandins
Volume15
Issue number5
DOIs
StatePublished - May 1978

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