The tiniest features of different enzymes and membrane proteins, that take part in drug metabolism, are determined genetically. These features affect the function of these molecules which means that every one of us processes same drugs differently.
As for a 69-year-old woman, Airi was no exception. She had been prescribed several medications: there was one for high blood pressure, for cholesterol, sweating and stomach related symptoms. It was quite a handful to keep a record of.