The novel positively charged pro-drugs of acetaminophen, acetaminosalol, and related compounds in the general formula (1) Structure 1 were designed and synthesized. The positively charged amino groups of these pro-drugs not only largely increases the solubility of the drugs, but also bonds to the negative charge on the phosphate head group of membranes and pushes the pro-drug into the cytosol. The results suggest that the pro-drugs diffuses through human skin ∼150 times faster than does acetaminophen, acetaminosalol, and related compounds. It takes 1-2 hours for acetaminophen and acetaminosalol, and related compounds to reach the peak plasma level when they are taken orally, but these prodrugs only took about ∼50 minutes to reach the peak plasma level when they are taken transdermally. In plasma, more than 90% of these pro-drugs can be changed back to the parent drugs in a few minutes. The prodrugs can be used medicinally for treating any NSAIAs-treatable conditions in humans or animals. The prodrugs can be administered not only orally, but also transdermally for any kind of medical treatments and avoid most of the side effects of NSAIAs. Controlled transdermal administration systems of the prodrugs enables acetaminophen, acetaminosalol, and related compounds to reach constantly optimal therapeutic blood levels to increase effectiveness and reduce the side effects of acetaminophen, acetaminosalol, and related compounds. Another great benefit of transdermal administration of these pro-drugs is that administering medication, especially to children, will be much easier.
