It is often a challenge to effectively deliver drugs through the skin into the internal environment. Compared with oral administration and other dosage forms, transdermal administration has multiple advantages. Among the various transdermal administration approaches, microneedles emerge as a powerful tool in recent years, owing to its simple concept and proven efficacy. In this project, we aim to develop a hot-embossing method using menthol as the carrier material to fabricate drug-laden microneedle patches. We compared the transdermal delivery of several drugs with different dosage forms and tried to enhance their transdermal absorption by chemical and physical enhancers including this menthol-based microneedle method. It is hypothesized that this approach can be used for chemicals with various properties to enhance their percutaneous absorption. For chemical drugs, we studied the transdermal absorption of cromolyn sodium in propylene glycol (PG) and the transdermal absorption of diclofenac diethylamine gels. For peptides, we studied an anti-pigmentation peptide with strong polarity, which has extremely low skin permeation. We esterified the peptide molecule to increase its lipophilicity for skin permeation. Following esterification, we studied the transdermal absorption of the peptide and its derivative in PG with chemical penetration enhancers. Apart from chemical permeation enhancement, we also used dissolving microneedles (MNs) as the physical method to enhance transdermal delivery of the chemicals and peptides. The transdermal experiments were carried out by using vertical Franz diffusion cells and cadaverous human skin samples. The results showed that in PG solution, the cumulative permeated amount of hydrophilic cromolyn sodium was very limited. In contrast, the lipophilic diclofenac showed much higher skin permeation than cromolyn sodium. For the native peptide in PG with or without permeation enhancers, the skin permeation was not detectable. However, after molecular modification, due to the enhancement of lipophilicity of peptide, its skin absorption was improved. Two penetration enhancers, namely oleic acid and camphor did not enhance the transdermal absorption of the esterified peptide while another chemical enhancer, namely, menthol, increased the skin absorption of the esterified peptide. For the physical enhancement, drug laden MN patches increased the skin permeation of all four permeants.