Minnesota’s fight to combat designer drugs meant to mimic marijuana and other controlled substances is stepping up a notch with a new law that makes their sale a felony. The law takes effect August 1st. It stiffens penalties for selling so-called synthetic drugs by making it a penalty that could carry a 5-year prison term. Current law limits prosecutors from charging more than a gross misdemeanor. The law also gives the state Pharmacy Board power to speed through new rules to keep up with the fast-changing formulas that the drug peddlers often use to evade existing laws. Just this week, Duluth police and federal authorities raided a head shop known for selling synthetic drugs as part of a nationwide crackdown on the substances.