It is a mistaken belief that Antabuse implants are infallible. The implants are fitted under the skin and disulfiram blocks the oxidisation of alcohol by the body, which results in toxins being released into the system when a person drinks alcohol, causing a range of unpleasant reactions. However, the individual effects vary from one person to the next.
Many people who have Antabuse implants fitted experiment with alcohol to see what their physical reaction is going to be, just as George Best did. Out of hundreds of Antabuse implants that I have personally fitted, I have found that about half of the patients experiment.
I was contacted by The Guardian on various occasions to explain how this worked in the case of George best. You can read those Guardian articles and more of my opinions on Antabuse Implants here: