Dr.iam 44 , i have problems in my penis erection when i consulted a doctor 3 years ago he made some test and sugested me to take Forzest 20 mg. tablets then it was alright , i dont take this tablet regularly but once a month. but last month i had back pane , when i went to the doctor to get some pain killers he suggested me to take my blood test and from that i came to know that my creatinine shows border. and rest everything is alright li ke bp., sugar, etc. but my doctor told me some familes of medecine is not good for me and he told me to avoid. now i want to know from you weather i can continue with tablet FORZEST 20 mg. or no. if no then which tablets should i take?.Please let me know Dr. thank you.