I'm calculating the drug release kinetics with the Korsmeyer-Peppas model. To find the exponent of release (n), I'm plotting in a log-log graph the percentage of drug release over time and I'm using data coming from the first 3 days of release. However, since the Mt/M ratio is less than 1, I get negative log(Mt/M). I've never seen this in papers, usually when people plot these data they have positive log(Mt/M), but I don't get how this can be.

Can you suggest me how should I plot these data? Because I'm probably doing it wrong.