Concomittant use of all the following drugs will cause failure of OCP except
Ans) c (Amiodarone) Ret: KDT 6th ed pg 27.405.701 516Many drugs, insecticides and carcinogens interact with DN A and increase the synthesis of microsomal enzyme protein, specially cytochrome P- 450and glucoronyl transferase. As a result rate of metabolism of inducing drug itself and or other drugs is increased.Phenytoin induces microsomal enzymes and increases degradation of steroids which results in failure ofOCPs, and drugs like digitoxin, doxycy-cline and theophylline.Ampicillin by inhibiting the colonic flora, may interfere with deconjugation and enterohepatic cycling of oral contraceptives which leads to failure of OCPs.Amiodarone is not regarded as an enzyme inducer. The inducers and inhibitors of CYP3A4 respectively decrease and increase amiodarone levels.Anticonvulsants including phenobarbitone, rifampin, glucocorticoids induce CYP3A isoenzymes.Phenobarbitone induce CYP2B1 and rifampin also induces CYP2D6 Isoniazid and chronic alcoholism induce CYP2E1Drugs whose metabolism is significantly affected by enzyme induction arePhenytoinChloramphenicolWarfarinDoxycyclineTolbutamideTheophyllineImipramineGriseofulvinOCPs
Ampicillin
Rifampicin
Amiodarone
Phenytoin
General Pharmacology