Probenecid increases the blood levels and half lives of many drugs. What i want to know is more specifically by how much?? What im wanting to know is more about famvir, how much longer does it increase the half life and is there some way of knowing what dose of a combo of probenecid/famvir is compared to just famvir, eg probenecid and 250mg famvir equal to 500mg famvir alone? This combo can make antivirals more economical. I had a month or maybe a bit longer off antivirals before viral symptoms returned. For 2 days i used 500mg twice a day and one of those doses was with probenecid. This seemed to help alot and stopped the rot in its tracks. Then i went back on my normal dose of 250mg twice a day, this doesnt seem to be cutting of late, probably need 500mg twice a day which costs $200 a month at this dose. I have 2 theories on possible dosing schedules i will talk over with my doc. One is the 250mg twice a day with probenecid on one of those doses or maybe both. The other is just 1x 500mg dose of famvir with probenecid. The second schedule i would prefer as i think the 500mg dose will have a higher blood level but it depends on how much probenecid increases half life. If its only a couple of hours it may not be worth it, if its 8hrs then i think it would work well. Currently the half life is only 2-3hrs and i have read the intracellular half life is 16hrs? not sure what the difference is really?? But dosing compared to other avs seems less often with famvir. Just thought of another question, how would probenecid work with immunovir, as they would seem to counteract one another. Probenecid lowers uric acid and immunovir can increase uric acid, i wonder if this effects the immune stimulating effects of immunovir???? cheers!!