This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': 'Drug which interferes effectiveness of OCP are all, EXCEPT: \nSelect and explain. \nA. Aspirin, B. Phenobarbital, C. Rifampicin, D. Primidone', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Contraceptive failure may occur if the following drugs are used concurrently: Enzyme inducers like Phenytoin, Phenobarbital, primidone, carbamazepine, rifampin. It will increase the metabolism of estrogenic as well as progestational component. Suppression of intestinal microflora: Tetracyclines and ampicillin etc. No deconjugation of estrogens excreted in bile-their enterohepatic circulation is interrupted-blood levels fall. Also Know: Absolute Contraindication of OCP: Thromboembolic, coronary and cerebrovascular disease or history of it Moderate to severe hypeension Hyperlipidemia Active liver disease Hepatoma H/o of jaundice during past pregnancy Malignancy of Breast/genitalis Porphyria Impending major surgery- to avoid postoperative thromboembolism. Ref: K.D.T. 6th Ed Page 317', 'role': 'assistant'}]