Generally, if you were not mentally competent at the time, including due to intoxication or medication, you lacked the capacity to enter into a contract and you can void the contract. That said, even if you were not competent--even if you were not conscious--you are responsible for and can be required to pay the cost of necessary medical treatment you received. So if the documents were about the medical care you needed and received, you will most likely have to oay despite any incapacity.