Without more information, it is not possible to determine how much medicine was in Mr. Jones's body when he first took it. Factors such as the type of medicine, the dosage Mr. Jones was taking, and his metabolism can all affect the amount of time it takes for the medicine to be metabolized and eliminated from his body. Additionally, the information provided does not include the amount of medicine in Mr. Jones's body at any time other than 1, 2, and 5 hours after he took it. To determine the amount of medicine in his body when he first took it, we would need to know the rate at which the medicine is metabolized and eliminated from his body, as well as the amount of medicine in his body at other time points. It is important for Mr. Jones to follow the instructions given to him by his doctor and to consult with his doctor if he has any questions or concerns.