Metamizole pharmacokinetics

The concurrent use of 20 mL of Maaloxan (aluminium/magnesium hydroxide gel) was reported to have had no effect on the pharmacokinetics of the metabolites of metamizole sodium. ... 

Bacracheva N, Tyutyulkova N, Drenska A, Gorantcheva J, Schinzel S, Scholl T, Stoinov A, Tchakarski I, tentcheva J, Vlahov V. Effect of cimetidine on the pharmacokinetics of the metabolites of metamizol. IntJClin Pharmacol Ther (1997) 35, 275-81. 

A study in untreated patients with leprosy showed that the pharmacokinetics of a single 600-mg dose of rifampicin were not markedly changed by 1 g of metamizole sodium (dipyrone), but peak serum rifampicin levels occurred sooner (at 3 instead of 4 hours) and were about 50% higher. ... 

Although information is limited, these pharmacokinetic interactions appear to be established. Their clinical relevance remains to be determine, but it seems likely that the efficacy of these NSAIDs will be reduced by rifampicin. Combined use should be well monitored, and the NSAID dosage increased if necessary. See also NSAIDs Parecoxib -i- Miscellane-ous%p.l60. The clinical relevance ofthe increase in rifampicin maximum levels with metamizole is uncertain. 

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