Belara Drug Interactions

The contraceptive effectiveness of Belara may be affected if substances that speed up the biological breakdown of steroid hormones eg, barbiturates, rifampicin, griseofulvin, phenylbutazone, antiepileptics (eg, barbexaclone, carbamazepine, phenytoin, primidone) and preparations containing St. John's wort and oral contraceptives at the same time spotting has been reported.
Reduced active substance levels have also been observed due to changes in the bowel flora when antibiotics eg, ampicillin or tetracyclines were taken at the same time, and also after taking activated charcoal. Also, increased rates of spotting and in isolated cases, pregnancy has been recorded. Requirements of insulin or antidiabetic medicines taken by mouth may be altered due to effects on glucose tolerance. The excretion of theophylline or caffeine is reduced during the use of oral contraceptives with the result that the effect of theophylline or caffeine may be increased and prolonged.