Phenazone Phenobarbital

Mokry, M. Khmes, J. Zahradnicek, M. HPLC analysis of some sulfonamides in selected pharmaceutical formulations. Pharmazie, 1994, 49, 333-335 [tablets injections acetanilide (IS) simultaneous sulfamethoxazole also phenacetin, phenazone, phenobarbital, phthalylsulfathiazole, sulfadimidine, sulfamethoxazole, sulftunethoxydiazine, sulfamoxole, sulfisoxazole]... 

The probable reason is that the phenobarbital increases the metabolism of these NSAIDs by the liver, thereby hastening their clearance. Phenazone is metabolised by mixed function oxidase enzymes in the liver, for which reason it is extensively used as a model drug for studying whether other drugs induce or inhibit liver enzymes. In one study phenobarbital caused about a 40% reduction thereby demonstrating that the liver enzymes were being stimulated to metabolise the phenazone more rapidly. The clinical importance of these interactions is uncertain (probably small) but be alert for any evidence of reduced NSAID effects if phenobarbital is added. 

Qf-Peroxylactone see l,2-dioxetan-3-one Phaeophorbide 556 Phaeophytin 556 Phenanthridine 423, 428 Phenazine 499 Phenazone 248 Pheniramine 379 Phenobarbital 473 Phenothiazine 445 Phenoxathiin 439... 

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