The effects of cefonicid on the pharmacokinetics of a once-a-day theophylline formulation.

The authors have explored the effects of cefonicid on the steady-state pharmacokinetics of a new sustained-release theophylline formulation in 12 adult patients suffering from chronic obstructive lung disease, by comparing the pharmacokinetic data obtained following four days of medication with theophylline alone with those found at the end of seven days of combined treatment with the same theophylline preparation plus cefonicid. Blood theophylline levels were assessed in duplicate by polarized immunofluorescence with a TDx analyser. Theophylline kinetics were totally unaffected by simultaneous cefonicid treatment, showing that the two drugs may be administered together without any need for adjustment of the theophylline dosage.